![YAML vs JSON
apiVersion: v1
kind: Pod
metadata:
name: pod-example
spec:
containers:
- name: nginx
image: nginx:stable-alpine
ports:
- containerPort: 80
{
"apiVersion": "v1",
"kind": "Pod",
"metadata": {
"name": "pod-example"
},
"spec": {
"containers": [
{
"name": "nginx",
"image": "nginx:stable-alpine",
"ports": [ { "containerPort": 80 } ]
}
]
}
}](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-62-320.jpg)
![Pod Examples
apiVersion: v1
kind: Pod
metadata:
name: multi-container-example
spec:
containers:
- name: nginx
image: nginx:stable-alpine
ports:
- containerPort: 80
volumeMounts:
- name: html
mountPath: /usr/share/nginx/html
- name: content
image: alpine:latest
command: ["/bin/sh", "-c"]
args:
- while true; do
date >> /html/index.html;
sleep 5;
done
volumeMounts:
- name: html
mountPath: /html
volumes:
- name: html
emptyDir: {}
apiVersion: v1
kind: Pod
metadata:
name: pod-example
spec:
containers:
- name: nginx
image: nginx:stable-alpine
ports:
- containerPort: 80](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-71-320.jpg)
![Key Pod Container Attributes
● name - The name of the container
● image - The container image
● ports - array of ports to expose.
Can be granted a friendly name and
protocol may be specified
● env - array of environment variables
● command - Entrypoint array (equiv
to Docker ENTRYPOINT)
● args - Arguments to pass to the
command (equiv to Docker CMD)
Container
name: nginx
image: nginx:stable-alpine
ports:
- containerPort: 80
name: http
protocol: TCP
env:
- name: MYVAR
value: isAwesome
command: [“/bin/sh”, “-c”]
args: [“echo ${MYVAR}”]](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-72-320.jpg)
![Equality based selectors allow for
simple filtering (=,==, or !=).
Selector Types
Set-based selectors are supported
on a limited subset of objects.
However, they provide a method of
filtering on a set of values, and
supports multiple operators including:
in, notin, and exist.
selector:
matchExpressions:
- key: gpu
operator: in
values: [“nvidia”]
selector:
matchLabels:
gpu: nvidia](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-77-320.jpg)
![StatefulSet
apiVersion: apps/v1
kind: StatefulSet
metadata:
name: sts-example
spec:
replicas: 2
revisionHistoryLimit: 3
selector:
matchLabels:
app: stateful
serviceName: app
updateStrategy:
type: RollingUpdate
rollingUpdate:
partition: 0
template:
metadata:
labels:
app: stateful
<continued>
<continued>
spec:
containers:
- name: nginx
image: nginx:stable-alpine
ports:
- containerPort: 80
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumeClaimTemplates:
- metadata:
name: www
spec:
accessModes: [ "ReadWriteOnce" ]
storageClassName: standard
resources:
requests:
storage: 1Gi](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-112-320.jpg)
![StatefulSet
spec:
containers:
- name: nginx
image: nginx:stable-alpine
ports:
- containerPort: 80
volumeMounts:
- name: www
mountPath: /usr/share/nginx/html
volumeClaimTemplates:
- metadata:
name: www
spec:
accessModes: [ "ReadWriteOnce" ]
storageClassName: standard
resources:
requests:
storage: 1Gi
● volumeClaimTemplates:
Template of the persistent
volume(s) request to use for
each instance of the StatefulSet.](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-118-320.jpg)
![VolumeClaimTemplate
volumeClaimTemplates:
- metadata:
name: www
spec:
accessModes: [ "ReadWriteOnce" ]
storageClassName: standard
resources:
requests:
storage: 1Gi
$ kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
www-sts-example-0 Bound pvc-d2f11e3b-18d0-11e8-ba4f-080027a3682b 1Gi RWO standard 4h
www-sts-example-1 Bound pvc-d3c923c0-18d0-11e8-ba4f-080027a3682b 1Gi RWO standard 4h
<Volume Name>-<StatefulSet Name>-<ordinal>
Persistent Volumes associated with a
StatefulSet will NOT be automatically
garbage collected when it’s associated
StatefulSet is deleted. They must manually
be removed.](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-119-320.jpg)
![Job
apiVersion: batch/v1
kind: Job
metadata:
name: job-example
spec:
backoffLimit: 4
completions: 4
parallelism: 2
template:
spec:
containers:
- name: hello
image: alpine:latest
command: ["/bin/sh", "-c"]
args: ["echo hello from $HOSTNAME!"]
restartPolicy: Never
$ kubectl describe job job-example
Name: job-example
Namespace: default
Selector: controller-uid=19d122f4-1576-11e8-a4e2-080027a3682b
Labels: controller-uid=19d122f4-1576-11e8-a4e2-080027a3682b
job-name=job-example
Annotations: <none>
Parallelism: 2
Completions: 4
Start Time: Mon, 19 Feb 2018 08:09:21 -0500
Pods Statuses: 0 Running / 4 Succeeded / 0 Failed
Pod Template:
Labels: controller-uid=19d122f4-1576-11e8-a4e2-080027a3682b
job-name=job-example
Containers:
hello:
Image: alpine:latest
Port: <none>
Command:
/bin/sh
-c
Args:
echo hello from $HOSTNAME!
Environment: <none>
Mounts: <none>
Volumes: <none>
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulCreate 52m job-controller Created pod: job-example-v5fvq
Normal SuccessfulCreate 52m job-controller Created pod: job-example-hknns
Normal SuccessfulCreate 51m job-controller Created pod: job-example-tphkm
Normal SuccessfulCreate 51m job-controller Created pod: job-example-dvxd2
$ kubectl get pods --show-all
NAME READY STATUS RESTARTS AGE
job-example-dvxd2 0/1 Completed 0 51m
job-example-hknns 0/1 Completed 0 52m
job-example-tphkm 0/1 Completed 0 51m
job-example-v5fvq 0/1 Completed 0 52m](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-122-320.jpg)
![CronJob
$ kubectl describe cronjob cronjob-example
Name: cronjob-example
Namespace: default
Labels: <none>
Annotations: <none>
Schedule: */1 * * * *
Concurrency Policy: Allow
Suspend: False
Starting Deadline Seconds: <unset>
Selector: <unset>
Parallelism: 2
Completions: 4
Pod Template:
Labels: <none>
Containers:
hello:
Image: alpine:latest
Port: <none>
Command:
/bin/sh
-c
Args:
echo hello from $HOSTNAME!
Environment: <none>
Mounts: <none>
Volumes: <none>
Last Schedule Time: Mon, 19 Feb 2018 09:54:00 -0500
Active Jobs: cronjob-example-1519052040
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal SuccessfulCreate 3m cronjob-controller Created job cronjob-example-1519051860
Normal SawCompletedJob 2m cronjob-controller Saw completed job: cronjob-example-1519051860
Normal SuccessfulCreate 2m cronjob-controller Created job cronjob-example-1519051920
Normal SawCompletedJob 1m cronjob-controller Saw completed job: cronjob-example-1519051920
Normal SuccessfulCreate 1m cronjob-controller Created job cronjob-example-1519051980
apiVersion: batch/v1beta1
kind: CronJob
metadata:
name: cronjob-example
spec:
schedule: "*/1 * * * *"
successfulJobsHistoryLimit: 3
failedJobsHistoryLimit: 1
jobTemplate:
spec:
completions: 4
parallelism: 2
template:
spec:
containers:
- name: hello
image: alpine:latest
command: ["/bin/sh", "-c"]
args: ["echo hello from $HOSTNAME!"]
restartPolicy: Never
$ kubectl get jobs
NAME DESIRED SUCCESSFUL AGE
cronjob-example-1519053240 4 4 2m
cronjob-example-1519053300 4 4 1m
cronjob-example-1519053360 4 4 26s](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-125-320.jpg)
![Volumes
● volumes: A list of volume objects to
be attached to the Pod. Every object
within the list must have it’s own
unique name.
● volumeMounts: A container specific
list referencing the Pod volumes by
name, along with their desired
mountPath.
apiVersion: v1
kind: Pod
metadata:
name: volume-example
spec:
containers:
- name: nginx
image: nginx:stable-alpine
volumeMounts:
- name: html
mountPath: /usr/share/nginx/html
ReadOnly: true
- name: content
image: alpine:latest
command: ["/bin/sh", "-c"]
args:
- while true; do
date >> /html/index.html;
sleep 5;
done
volumeMounts:
- name: html
mountPath: /html
volumes:
- name: html
emptyDir: {}](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-131-320.jpg)
![Volumes
● volumes: A list of volume objects to
be attached to the Pod. Every object
within the list must have it’s own
unique name.
● volumeMounts: A container specific
list referencing the Pod volumes by
name, along with their desired
mountPath.
apiVersion: v1
kind: Pod
metadata:
name: volume-example
spec:
containers:
- name: nginx
image: nginx:stable-alpine
volumeMounts:
- name: html
mountPath: /usr/share/nginx/html
ReadOnly: true
- name: content
image: alpine:latest
command: ["/bin/sh", "-c"]
args:
- while true; do
date >> /html/index.html;
sleep 5;
done
volumeMounts:
- name: html
mountPath: /html
volumes:
- name: html
emptyDir: {}](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-132-320.jpg)
![Volumes
● volumes: A list of volume objects to
be attached to the Pod. Every object
within the list must have it’s own
unique name.
● volumeMounts: A container specific
list referencing the Pod volumes by
name, along with their desired
mountPath.
apiVersion: v1
kind: Pod
metadata:
name: volume-example
spec:
containers:
- name: nginx
image: nginx:stable-alpine
volumeMounts:
- name: html
mountPath: /usr/share/nginx/html
ReadOnly: true
- name: content
image: alpine:latest
command: ["/bin/sh", "-c"]
args:
- while true; do
date >> /html/index.html;
sleep 5;
done
volumeMounts:
- name: html
mountPath: /html
volumes:
- name: html
emptyDir: {}](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-133-320.jpg)
![Injecting as Environment Variable
apiVersion: batch/v1
kind: Job
metadata:
name: cm-env-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“printenv CITY”]
env:
- name: CITY
valueFrom:
configMapKeyRef:
name: manifest-example
key: city
restartPolicy: Never
apiVersion: batch/v1
kind: Job
metadata:
name: secret-env-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“printenv USERNAME”]
env:
- name: USERNAME
valueFrom:
secretKeyRef:
name: manifest-example
key: username
restartPolicy: Never](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-162-320.jpg)
![Injecting as Environment Variable
apiVersion: batch/v1
kind: Job
metadata:
name: cm-env-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“printenv CITY”]
env:
- name: CITY
valueFrom:
configMapKeyRef:
name: manifest-example
key: city
restartPolicy: Never
apiVersion: batch/v1
kind: Job
metadata:
name: secret-env-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“printenv USERNAME”]
env:
- name: USERNAME
valueFrom:
secretKeyRef:
name: manifest-example
key: username
restartPolicy: Never](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-163-320.jpg)
![Injecting in a Command
apiVersion: batch/v1
kind: Job
metadata:
name: cm-cmd-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“echo Hello ${CITY}!”]
env:
- name: CITY
valueFrom:
configMapKeyRef:
name: manifest-example
key: city
restartPolicy: Never
apiVersion: batch/v1
kind: Job
metadata:
name: secret-cmd-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“echo Hello ${USERNAME}!”]
env:
- name: USERNAME
valueFrom:
secretKeyRef:
name: manifest-example
key: username
restartPolicy: Never](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-164-320.jpg)
![Injecting in a Command
apiVersion: batch/v1
kind: Job
metadata:
name: cm-cmd-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“echo Hello ${CITY}!”]
env:
- name: CITY
valueFrom:
configMapKeyRef:
name: manifest-example
key: city
restartPolicy: Never
apiVersion: batch/v1
kind: Job
metadata:
name: secret-cmd-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“echo Hello ${USERNAME}!”]
env:
- name: USERNAME
valueFrom:
secretKeyRef:
name: manifest-example
key: username
restartPolicy: Never](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-165-320.jpg)
![Injecting as a Volume
apiVersion: batch/v1
kind: Job
metadata:
name: cm-vol-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“cat /myconfig/city”]
volumeMounts:
- name: config-volume
mountPath: /myconfig
restartPolicy: Never
volumes:
- name: config-volume
configMap:
name: manifest-example
apiVersion: batch/v1
kind: Job
metadata:
name: secret-vol-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“cat /mysecret/username”]
volumeMounts:
- name: secret-volume
mountPath: /mysecret
restartPolicy: Never
volumes:
- name: secret-volume
secret:
secretName: manifest-example](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-166-320.jpg)
![Injecting as a Volume
apiVersion: batch/v1
kind: Job
metadata:
name: cm-vol-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“cat /myconfig/city”]
volumeMounts:
- name: config-volume
mountPath: /myconfig
restartPolicy: Never
volumes:
- name: config-volume
configMap:
name: manifest-example
apiVersion: batch/v1
kind: Job
metadata:
name: secret-vol-example
spec:
template:
spec:
containers:
- name: mypod
image: alpine:latest
command: [“/bin/sh”, “-c”]
args: [“cat /mysecret/username”]
volumeMounts:
- name: secret-volume
mountPath: /mysecret
restartPolicy: Never
volumes:
- name: secret-volume
secret:
secretName: manifest-example](https://image.slidesharecdn.com/introductiontokubernetes-210506225324/85/Introduction-to-kubernetes-167-320.jpg)
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Introduction to kubernetes
- 1. Kubernetes An Introduction Kubernetes v1.15 07/2019 CC-BY 4.0
- 2. Before We Begin Requirements: ● Minikube: https://github.com/kubernetes/minikube ● Virtualbox*: https://www.virtualbox.org/wiki/Downloads ● kubectl: https://kubernetes.io/docs/tasks/tools/install-kubectl/ ● k8s-intro-tutorials repo: https://github.com/mrbobbytables/k8s-intro-tutorials
- 3. Before We Begin Go here for install instructions https://goo.gl/1HV3Tu
- 4. Kubernetes An Introduction Kubernetes v1.15 07/2019 CC-BY 4.0
- 5. $ whoami - Bob Bob Killen [email protected] Senior Research Cloud Administrator CNCF Ambassador Github: @mrbobbytables Twitter: @mrbobbytables
- 6. $ whoami - Jeff Jeffrey Sica [email protected] Senior Software Engineer @ Github: @jeefy Twitter: @jeefy
- 8. What Does “Kubernetes” Mean? Greek for “pilot” or “Helmsman of a ship” Image Source
- 9. What is Kubernetes? ● Project that was spun out of Google as an open source container orchestration platform. ● Built from the lessons learned in the experiences of developing and running Google’s Borg and Omega. ● Designed from the ground-up as a loosely coupled collection of components centered around deploying, maintaining and scaling workloads.
- 10. What Does Kubernetes do? ● Known as the linux kernel of distributed systems. ● Abstracts away the underlying hardware of the nodes and provides a uniform interface for workloads to be both deployed and consume the shared pool of resources. ● Works as an engine for resolving state by converging actual and the desired state of the system.
- 11. Decouples Infrastructure and Scaling ● All services within Kubernetes are natively Load Balanced. ● Can scale up and down dynamically. ● Used both to enable self-healing and seamless upgrading or rollback of applications.
- 12. Self Healing Kubernetes will ALWAYS try and steer the cluster to its desired state. ● Me: “I want 3 healthy instances of redis to always be running.” ● Kubernetes: “Okay, I’ll ensure there are always 3 instances up and running.” ● Kubernetes: “Oh look, one has died. I’m going to attempt to spin up a new one.”
- 13. What can Kubernetes REALLY do? ● Autoscale Workloads ● Blue/Green Deployments ● Fire off jobs and scheduled cronjobs ● Manage Stateless and Stateful Applications ● Provide native methods of service discovery ● Easily integrate and support 3rd party apps
- 14. Most Importantly... Use the SAME API across bare metal and EVERY cloud provider!!!
- 15. Who “Manages” Kubernetes? The CNCF is a child entity of the Linux Foundation and operates as a vendor neutral governance group.
- 16. Project Stats ● Over 55,000 stars on Github ● 2000+ Contributors to K8s Core ● Most discussed Repository by a large margin ● 70,000+ users in Slack Team 07/2019
- 17. Project Stats
- 19. Pods ● Atomic unit or smallest “unit of work”of Kubernetes. ● Pods are one or MORE containers that share volumes, a network namespace, and are a part of a single context.
- 21. Services ● Unified method of accessing the exposed workloads of Pods. ● Durable resource ○ static cluster IP ○ static namespaced DNS name
- 22. Services ● Unified method of accessing the exposed workloads of Pods. ● Durable resource ○ static cluster IP ○ static namespaced DNS name NOT Ephemeral!
- 26. Control Plane Components ● kube-apiserver ● etcd ● kube-controller-manager ● kube-scheduler
- 27. kube-apiserver ● Provides a forward facing REST interface into the kubernetes control plane and datastore. ● All clients and other applications interact with kubernetes strictly through the API Server. ● Acts as the gatekeeper to the cluster by handling authentication and authorization, request validation, mutation, and admission control in addition to being the front-end to the backing datastore.
- 28. etcd ● etcd acts as the cluster datastore. ● Purpose in relation to Kubernetes is to provide a strong, consistent and highly available key-value store for persisting cluster state. ● Stores objects and config information.
- 29. etcd Uses “Raft Consensus” among a quorum of systems to create a fault-tolerant consistent “view” of the cluster. https://raft.github.io/ Image Source
- 30. kube-controller-manager ● Serves as the primary daemon that manages all core component control loops. ● Monitors the cluster state via the apiserver and steers the cluster towards the desired state. List of core controllers: https://github.com/kubernetes/kubernetes/blob/master/cmd/kube-controller-manager/app/controllermanager.go#L344
- 31. kube-scheduler ● Verbose policy-rich engine that evaluates workload requirements and attempts to place it on a matching resource. ● Default scheduler uses bin packing. ● Workload Requirements can include: general hardware requirements, affinity/anti-affinity, labels, and other various custom resource requirements.
- 33. Node Components ● kubelet ● kube-proxy ● Container Runtime Engine
- 34. kubelet ● Acts as the node agent responsible for managing the lifecycle of every pod on its host. ● Kubelet understands YAML container manifests that it can read from several sources: ○ file path ○ HTTP Endpoint ○ etcd watch acting on any changes ○ HTTP Server mode accepting container manifests over a simple API.
- 35. kube-proxy ● Manages the network rules on each node. ● Performs connection forwarding or load balancing for Kubernetes cluster services. ● Available Proxy Modes: ○ Userspace ○ iptables ○ ipvs (default if supported)
- 36. Container Runtime Engine ● A container runtime is a CRI (Container Runtime Interface) compatible application that executes and manages containers. ○ Containerd (docker) ○ Cri-o ○ Rkt ○ Kata (formerly clear and hyper) ○ Virtlet (VM CRI compatible runtime)
- 39. cloud-controller-manager ● Daemon that provides cloud-provider specific knowledge and integration capability into the core control loop of Kubernetes. ● The controllers include Node, Route, Service, and add an additional controller to handle things such as PersistentVolume Labels.
- 40. Cluster DNS ● Provides Cluster Wide DNS for Kubernetes Services. ○ Built on top of CoreDNS
- 41. Kube Dashboard A limited, general purpose web front end for the Kubernetes Cluster.
- 42. Heapster / Metrics API Server ● Provides metrics for use with other Kubernetes Components. ○ Heapster (deprecated, removed last Dec) ○ Metrics API (current)
- 44. Kubernetes Networking ● Pod Network ○ Cluster-wide network used for pod-to-pod communication managed by a CNI (Container Network Interface) plugin. ● Service Network ○ Cluster-wide range of Virtual IPs managed by kube-proxy for service discovery.
- 45. Container Network Interface (CNI) ● Pod networking within Kubernetes is plumbed via the Container Network Interface (CNI). ● Functions as an interface between the container runtime and a network implementation plugin. ● CNCF Project ● Uses a simple JSON Schema.
- 46. CNI Overview
- 47. CNI Overview
- 48. CNI Plugins ● Amazon ECS ● Calico ● Cillium ● Contiv ● Contrail ● Flannel ● GCE ● kube-router ● Multus ● OpenVSwitch ● Romana ● Weave
- 49. Fundamental Networking Rules ● All containers within a pod can communicate with each other unimpeded. ● All Pods can communicate with all other Pods without NAT. ● All nodes can communicate with all Pods (and vice-versa) without NAT. ● The IP that a Pod sees itself as is the same IP that others see it as.
- 50. Fundamentals Applied ● Container-to-Container ○ Containers within a pod exist within the same network namespace and share an IP. ○ Enables intrapod communication over localhost. ● Pod-to-Pod ○ Allocated cluster unique IP for the duration of its life cycle. ○ Pods themselves are fundamentally ephemeral.
- 51. Fundamentals Applied ● Pod-to-Service ○ managed by kube-proxy and given a persistent cluster unique IP ○ exists beyond a Pod’s lifecycle. ● External-to-Service ○ Handled by kube-proxy. ○ Works in cooperation with a cloud provider or other external entity (load balancer).
- 53. Concepts and Resources The API and Object Model
- 54. API Overview ● The REST API is the true keystone of Kubernetes. ● Everything within the Kubernetes is as an API Object. Image Source
- 55. API Groups ● Designed to make it extremely simple to both understand and extend. ● An API Group is a REST compatible path that acts as the type descriptor for a Kubernetes object. ● Referenced within an object as the apiVersion and kind. Format: /apis/<group>/<version>/<resource> Examples: /apis/apps/v1/deployments /apis/batch/v1beta1/cronjobs
- 56. API Versioning ● Three tiers of API maturity levels. ● Also referenced within the object apiVersion. ● Alpha: Possibly buggy, And may change. Disabled by default. ● Beta: Tested and considered stable. However API Schema may change. Enabled by default. ● Stable: Released, stable and API schema will not change. Enabled by default. Format: /apis/<group>/<version>/<resource> Examples: /apis/apps/v1/deployments /apis/batch/v1beta1/cronjobs
- 57. Object Model ● Objects are a “record of intent” or a persistent entity that represent the desired state of the object within the cluster. ● All objects MUST have apiVersion, kind, and poses the nested fields metadata.name, metadata.namespace, and metadata.uid.
- 58. Object Model Requirements ● apiVersion: Kubernetes API version of the Object ● kind: Type of Kubernetes Object ● metadata.name: Unique name of the Object ● metadata.namespace: Scoped environment name that the object belongs to (will default to current). ● metadata.uid: The (generated) uid for an object. apiVersion: v1 kind: Pod metadata: name: pod-example namespace: default uid: f8798d82-1185-11e8-94ce-080027b3c7a6
- 59. Object Expression - YAML ● Files or other representations of Kubernetes Objects are generally represented in YAML. ● A “Human Friendly” data serialization standard. ● Uses white space (specifically spaces) alignment to denote ownership. ● Three basic data types: ○ mappings - hash or dictionary, ○ sequences - array or list ○ scalars - string, number, boolean etc
- 60. Object Expression - YAML apiVersion: v1 kind: Pod metadata: name: yaml spec: containers: - name: container1 image: nginx - name: container2 image: alpine
- 61. Object Expression - YAML apiVersion: v1 kind: Pod metadata: name: yaml spec: containers: - name: container1 image: nginx - name: container2 image: alpine Sequence Array List Mapping Hash Dictionary Scalar
- 62. YAML vs JSON apiVersion: v1 kind: Pod metadata: name: pod-example spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 { "apiVersion": "v1", "kind": "Pod", "metadata": { "name": "pod-example" }, "spec": { "containers": [ { "name": "nginx", "image": "nginx:stable-alpine", "ports": [ { "containerPort": 80 } ] } ] } }
- 63. Object Model - Workloads ● Workload related objects within Kubernetes have an additional two nested fields spec and status. ○ spec - Describes the desired state or configuration of the object to be created. ○ status - Is managed by Kubernetes and describes the actual state of the object and its history.
- 64. Workload Object Example Example Object apiVersion: v1 kind: Pod metadata: name: pod-example spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 Example Status Snippet status: conditions: - lastProbeTime: null lastTransitionTime: 2018-02-14T14:15:52Z status: "True" type: Ready - lastProbeTime: null lastTransitionTime: 2018-02-14T14:15:49Z status: "True" type: Initialized - lastProbeTime: null lastTransitionTime: 2018-02-14T14:15:49Z status: "True" type: PodScheduled
- 65. Lab - github.com/mrbobbytables/k8s-intro-tutorials/blob/master/cli Using the API (aka, using the CLI)
- 66. Concepts and Resources Core Objects ● Namespaces ● Pods ● Labels ● Selectors ● Services
- 67. Core Concepts Kubernetes has several core building blocks that make up the foundation of their higher level components. Namespaces Pods Selectors Services Labels
- 68. Namespaces Namespaces are a logical cluster or environment, and are the primary method of partitioning a cluster or scoping access. apiVersion: v1 kind: Namespace metadata: name: prod labels: app: MyBigWebApp $ kubectl get ns --show-labels NAME STATUS AGE LABELS default Active 11h <none> kube-public Active 11h <none> kube-system Active 11h <none> prod Active 6s app=MyBigWebApp
- 69. Default Namespaces $ kubectl get ns --show-labels NAME STATUS AGE LABELS default Active 11h <none> kube-public Active 11h <none> kube-system Active 11h <none> ● default: The default namespace for any object without a namespace. ● kube-system: Acts as the home for objects and resources created by Kubernetes itself. ● kube-public: A special namespace; readable by all users that is reserved for cluster bootstrapping and configuration.
- 70. Pod ● Atomic unit or smallest “unit of work”of Kubernetes. ● Foundational building block of Kubernetes Workloads. ● Pods are one or more containers that share volumes, a network namespace, and are a part of a single context.
- 71. Pod Examples apiVersion: v1 kind: Pod metadata: name: multi-container-example spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 volumeMounts: - name: html mountPath: /usr/share/nginx/html - name: content image: alpine:latest command: ["/bin/sh", "-c"] args: - while true; do date >> /html/index.html; sleep 5; done volumeMounts: - name: html mountPath: /html volumes: - name: html emptyDir: {} apiVersion: v1 kind: Pod metadata: name: pod-example spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80
- 72. Key Pod Container Attributes ● name - The name of the container ● image - The container image ● ports - array of ports to expose. Can be granted a friendly name and protocol may be specified ● env - array of environment variables ● command - Entrypoint array (equiv to Docker ENTRYPOINT) ● args - Arguments to pass to the command (equiv to Docker CMD) Container name: nginx image: nginx:stable-alpine ports: - containerPort: 80 name: http protocol: TCP env: - name: MYVAR value: isAwesome command: [“/bin/sh”, “-c”] args: [“echo ${MYVAR}”]
- 73. Labels ● key-value pairs that are used to identify, describe and group together related sets of objects or resources. ● NOT characteristic of uniqueness. ● Have a strict syntax with a slightly limited character set*. * https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#syntax-and-character-set
- 74. Label Example apiVersion: v1 kind: Pod metadata: name: pod-label-example labels: app: nginx env: prod spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80
- 75. Selectors Selectors use labels to filter or select objects, and are used throughout Kubernetes. apiVersion: v1 kind: Pod metadata: name: pod-label-example labels: app: nginx env: prod spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 nodeSelector: gpu: nvidia
- 76. apiVersion: v1 kind: Pod metadata: name: pod-label-example labels: app: nginx env: prod spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 nodeSelector: gpu: nvidia Selector Example
- 77. Equality based selectors allow for simple filtering (=,==, or !=). Selector Types Set-based selectors are supported on a limited subset of objects. However, they provide a method of filtering on a set of values, and supports multiple operators including: in, notin, and exist. selector: matchExpressions: - key: gpu operator: in values: [“nvidia”] selector: matchLabels: gpu: nvidia
- 78. Services ● Unified method of accessing the exposed workloads of Pods. ● Durable resource (unlike Pods) ○ static cluster-unique IP ○ static namespaced DNS name <service name>.<namespace>.svc.cluster.local
- 79. Services ● Target Pods using equality based selectors. ● Uses kube-proxy to provide simple load-balancing. ● kube-proxy acts as a daemon that creates local entries in the host’s iptables for every service.
- 80. Service Types There are 4 major service types: ● ClusterIP (default) ● NodePort ● LoadBalancer ● ExternalName
- 81. ClusterIP Service ClusterIP services exposes a service on a strictly cluster internal virtual IP. apiVersion: v1 kind: Service metadata: name: example-prod spec: selector: app: nginx env: prod ports: - protocol: TCP port: 80 targetPort: 80
- 82. Cluster IP Service Name: example-prod Selector: app=nginx,env=prod Type: ClusterIP IP: 10.96.28.176 Port: <unset> 80/TCP TargetPort: 80/TCP Endpoints: 10.255.16.3:80, 10.255.16.4:80 / # nslookup example-prod.default.svc.cluster.local Name: example-prod.default.svc.cluster.local Address 1: 10.96.28.176 example-prod.default.svc.cluster.local
- 83. NodePort Service ● NodePort services extend the ClusterIP service. ● Exposes a port on every node’s IP. ● Port can either be statically defined, or dynamically taken from a range between 30000-32767. apiVersion: v1 kind: Service metadata: name: example-prod spec: type: NodePort selector: app: nginx env: prod ports: - nodePort: 32410 protocol: TCP port: 80 targetPort: 80
- 84. NodePort Service Name: example-prod Selector: app=nginx,env=prod Type: NodePort IP: 10.96.28.176 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 32410/TCP Endpoints: 10.255.16.3:80, 10.255.16.4:80
- 85. LoadBalancer Service apiVersion: v1 kind: Service metadata: name: example-prod spec: type: LoadBalancer selector: app: nginx env: prod ports: protocol: TCP port: 80 targetPort: 80 ● LoadBalancer services extend NodePort. ● Works in conjunction with an external system to map a cluster external IP to the exposed service.
- 86. LoadBalancer Service Name: example-prod Selector: app=nginx,env=prod Type: LoadBalancer IP: 10.96.28.176 LoadBalancer Ingress: 172.17.18.43 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 32410/TCP Endpoints: 10.255.16.3:80, 10.255.16.4:80
- 87. ExternalName Service apiVersion: v1 kind: Service metadata: name: example-prod spec: type: ExternalName spec: externalName: example.com ● ExternalName is used to reference endpoints OUTSIDE the cluster. ● Creates an internal CNAME DNS entry that aliases another.
- 90. Concepts and Resources Workloads ● ReplicaSet ● Deployment ● DaemonSet ● StatefulSet ● Job ● CronJob
- 92. Workloads Workloads within Kubernetes are higher level objects that manage Pods or other higher level objects. In ALL CASES a Pod Template is included, and acts the base tier of management.
- 93. Pod Template ● Workload Controllers manage instances of Pods based off a provided template. ● Pod Templates are Pod specs with limited metadata. ● Controllers use Pod Templates to make actual pods. apiVersion: v1 kind: Pod metadata: name: pod-example labels: app: nginx spec: containers: - name: nginx image: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx
- 94. ReplicaSet ● Primary method of managing pod replicas and their lifecycle. ● Includes their scheduling, scaling, and deletion. ● Their job is simple: Always ensure the desired number of pods are running.
- 95. ReplicaSet ● replicas: The desired number of instances of the Pod. ● selector:The label selector for the ReplicaSet will manage ALL Pod instances that it targets; whether it’s desired or not. apiVersion: apps/v1 kind: ReplicaSet metadata: name: rs-example spec: replicas: 3 selector: matchLabels: app: nginx env: prod template: <pod template>
- 96. ReplicaSet $ kubectl describe rs rs-example Name: rs-example Namespace: default Selector: app=nginx,env=prod Labels: app=nginx env=prod Annotations: <none> Replicas: 3 current / 3 desired Pods Status: 3 Running / 0 Waiting / 0 Succeeded / 0 Failed Pod Template: Labels: app=nginx env=prod Containers: nginx: Image: nginx:stable-alpine Port: 80/TCP Environment: <none> Mounts: <none> Volumes: <none> Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 16s replicaset-controller Created pod: rs-example-mkll2 Normal SuccessfulCreate 16s replicaset-controller Created pod: rs-example-b7bcg Normal SuccessfulCreate 16s replicaset-controller Created pod: rs-example-9l4dt apiVersion: apps/v1 kind: ReplicaSet metadata: name: rs-example spec: replicas: 3 selector: matchLabels: app: nginx env: prod template: metadata: labels: app: nginx env: prod spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 $ kubectl get pods NAME READY STATUS RESTARTS AGE rs-example-9l4dt 1/1 Running 0 1h rs-example-b7bcg 1/1 Running 0 1h rs-example-mkll2 1/1 Running 0 1h
- 97. Deployment ● Declarative method of managing Pods via ReplicaSets. ● Provide rollback functionality and update control. ● Updates are managed through the pod-template-hash label. ● Each iteration creates a unique label that is assigned to both the ReplicaSet and subsequent Pods.
- 98. Deployment ● revisionHistoryLimit: The number of previous iterations of the Deployment to retain. ● strategy: Describes the method of updating the Pods based on the type. Valid options are Recreate or RollingUpdate. ○ Recreate: All existing Pods are killed before the new ones are created. ○ RollingUpdate: Cycles through updating the Pods according to the parameters: maxSurge and maxUnavailable. apiVersion: apps/v1 kind: Deployment metadata: name: deploy-example spec: replicas: 3 revisionHistoryLimit: 3 selector: matchLabels: app: nginx env: prod strategy: type: RollingUpdate rollingUpdate: maxSurge: 1 maxUnavailable: 0 template: <pod template>
- 99. RollingUpdate Deployment $ kubectl get pods NAME READY STATUS RESTARTS AGE mydep-6766777fff-9r2zn 1/1 Running 0 5h mydep-6766777fff-hsfz9 1/1 Running 0 5h mydep-6766777fff-sjxhf 1/1 Running 0 5h $ kubectl get replicaset NAME DESIRED CURRENT READY AGE mydep-6766777fff 3 3 3 5h Updating pod template generates a new ReplicaSet revision. R1 pod-template-hash: 676677fff R2 pod-template-hash: 54f7ff7d6d
- 100. RollingUpdate Deployment $ kubectl get replicaset NAME DESIRED CURRENT READY AGE mydep-54f7ff7d6d 1 1 1 5s mydep-6766777fff 2 3 3 5h $ kubectl get pods NAME READY STATUS RESTARTS AGE mydep-54f7ff7d6d-9gvll 1/1 Running 0 2s mydep-6766777fff-9r2zn 1/1 Running 0 5h mydep-6766777fff-hsfz9 1/1 Running 0 5h mydep-6766777fff-sjxhf 1/1 Running 0 5h New ReplicaSet is initially scaled up based on maxSurge. R1 pod-template-hash: 676677fff R2 pod-template-hash: 54f7ff7d6d
- 101. RollingUpdate Deployment $ kubectl get pods NAME READY STATUS RESTARTS AGE mydep-54f7ff7d6d-9gvll 1/1 Running 0 5s mydep-54f7ff7d6d-cqvlq 1/1 Running 0 2s mydep-6766777fff-9r2zn 1/1 Running 0 5h mydep-6766777fff-hsfz9 1/1 Running 0 5h $ kubectl get replicaset NAME DESIRED CURRENT READY AGE mydep-54f7ff7d6d 2 2 2 8s mydep-6766777fff 2 2 2 5h Phase out of old Pods managed by maxSurge and maxUnavailable. R1 pod-template-hash: 676677fff R2 pod-template-hash: 54f7ff7d6d
- 102. RollingUpdate Deployment $ kubectl get replicaset NAME DESIRED CURRENT READY AGE mydep-54f7ff7d6d 3 3 3 10s mydep-6766777fff 0 1 1 5h $ kubectl get pods NAME READY STATUS RESTARTS AGE mydep-54f7ff7d6d-9gvll 1/1 Running 0 7s mydep-54f7ff7d6d-cqvlq 1/1 Running 0 5s mydep-54f7ff7d6d-gccr6 1/1 Running 0 2s mydep-6766777fff-9r2zn 1/1 Running 0 5h Phase out of old Pods managed by maxSurge and maxUnavailable. R1 pod-template-hash: 676677fff R2 pod-template-hash: 54f7ff7d6d
- 103. RollingUpdate Deployment $ kubectl get replicaset NAME DESIRED CURRENT READY AGE mydep-54f7ff7d6d 3 3 3 13s mydep-6766777fff 0 0 0 5h $ kubectl get pods NAME READY STATUS RESTARTS AGE mydep-54f7ff7d6d-9gvll 1/1 Running 0 10s mydep-54f7ff7d6d-cqvlq 1/1 Running 0 8s mydep-54f7ff7d6d-gccr6 1/1 Running 0 5s Phase out of old Pods managed by maxSurge and maxUnavailable. R1 pod-template-hash: 676677fff R2 pod-template-hash: 54f7ff7d6d
- 104. RollingUpdate Deployment $ kubectl get replicaset NAME DESIRED CURRENT READY AGE mydep-54f7ff7d6d 3 3 3 15s mydep-6766777fff 0 0 0 5h $ kubectl get pods NAME READY STATUS RESTARTS AGE mydep-54f7ff7d6d-9gvll 1/1 Running 0 12s mydep-54f7ff7d6d-cqvlq 1/1 Running 0 10s mydep-54f7ff7d6d-gccr6 1/1 Running 0 7s Updated to new deployment revision completed. R1 pod-template-hash: 676677fff R2 pod-template-hash: 54f7ff7d6d
- 105. DaemonSet ● Ensure that all nodes matching certain criteria will run an instance of the supplied Pod. ● They bypass default scheduling mechanisms. ● Are ideal for cluster wide services such as log forwarding, or health monitoring. ● Revisions are managed via a controller-revision-hash label.
- 106. DaemonSet ● revisionHistoryLimit: The number of previous iterations of the DaemonSet to retain. ● updateStrategy: Describes the method of updating the Pods based on the type. Valid options are RollingUpdate or OnDelete. ○ RollingUpdate: Cycles through updating the Pods according to the value of maxUnavailable. ○ OnDelete: The new instance of the Pod is deployed ONLY after the current instance is deleted. apiVersion: apps/v1 kind: DaemonSet metadata: name: ds-example spec: revisionHistoryLimit: 3 selector: matchLabels: app: nginx updateStrategy: type: RollingUpdate rollingUpdate: maxUnavailable: 1 template: spec: nodeSelector: nodeType: edge <pod template>
- 107. DaemonSet ● spec.template.spec.nodeSelector: The primary selector used to target nodes. ● Default Host Labels: ○ kubernetes.io/hostname ○ beta.kubernetes.io/os ○ beta.kubernetes.io/arch ● Cloud Host Labels: ○ failure-domain.beta.kubernetes.io/zone ○ failure-domain.beta.kubernetes.io/region ○ beta.kubernetes.io/instance-type apiVersion: apps/v1 kind: DaemonSet metadata: name: ds-example spec: revisionHistoryLimit: 3 selector: matchLabels: app: nginx updateStrategy: type: RollingUpdate rollingUpdate: maxUnavailable: 1 template: spec: nodeSelector: nodeType: edge <pod template>
- 108. DaemonSet $ kubectl describe ds ds-example Name: ds-example Selector: app=nginx,env=prod Node-Selector: nodeType=edge Labels: app=nginx env=prod Annotations: <none> Desired Number of Nodes Scheduled: 1 Current Number of Nodes Scheduled: 1 Number of Nodes Scheduled with Up-to-date Pods: 1 Number of Nodes Scheduled with Available Pods: 1 Number of Nodes Misscheduled: 0 Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed Pod Template: Labels: app=nginx env=prod Containers: nginx: Image: nginx:stable-alpine Port: 80/TCP Environment: <none> Mounts: <none> Volumes: <none> Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 48s daemonset-controller Created pod: ds-example-x8kkz apiVersion: apps/v1 kind: DaemonSet metadata: name: ds-example spec: revisionHistoryLimit: 3 selector: matchLabels: app: nginx updateStrategy: type: RollingUpdate rollingUpdate: maxUnavailable: 1 template: metadata: labels: app: nginx spec: nodeSelector: nodeType: edge containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 $ kubectl get pods NAME READY STATUS RESTARTS AGE ds-example-x8kkz 1/1 Running 0 1m
- 109. DaemonSet $ kubectl describe ds ds-example Name: ds-example Selector: app=nginx,env=prod Node-Selector: nodeType=edge Labels: app=nginx env=prod Annotations: <none> Desired Number of Nodes Scheduled: 1 Current Number of Nodes Scheduled: 1 Number of Nodes Scheduled with Up-to-date Pods: 1 Number of Nodes Scheduled with Available Pods: 1 Number of Nodes Misscheduled: 0 Pods Status: 1 Running / 0 Waiting / 0 Succeeded / 0 Failed Pod Template: Labels: app=nginx env=prod Containers: nginx: Image: nginx:stable-alpine Port: 80/TCP Environment: <none> Mounts: <none> Volumes: <none> Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 48s daemonset-controller Created pod: ds-example-x8kkz apiVersion: apps/v1 kind: DaemonSet metadata: name: ds-example spec: revisionHistoryLimit: 3 selector: matchLabels: app: nginx updateStrategy: type: RollingUpdate rollingUpdate: maxUnavailable: 1 template: metadata: labels: app: nginx spec: nodeSelector: nodeType: edge containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 $ kubectl get pods NAME READY STATUS RESTARTS AGE ds-example-x8kkz 1/1 Running 0 1m
- 110. StatefulSet ● Tailored to managing Pods that must persist or maintain state. ● Pod identity including hostname, network, and storage WILL be persisted. ● Assigned a unique ordinal name following the convention of ‘<statefulset name>-<ordinal index>’.
- 111. StatefulSet ● Naming convention is also used in Pod’s network Identity and Volumes. ● Pod lifecycle will be ordered and follow consistent patterns. ● Revisions are managed via a controller-revision-hash label
- 112. StatefulSet apiVersion: apps/v1 kind: StatefulSet metadata: name: sts-example spec: replicas: 2 revisionHistoryLimit: 3 selector: matchLabels: app: stateful serviceName: app updateStrategy: type: RollingUpdate rollingUpdate: partition: 0 template: metadata: labels: app: stateful <continued> <continued> spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 volumeMounts: - name: www mountPath: /usr/share/nginx/html volumeClaimTemplates: - metadata: name: www spec: accessModes: [ "ReadWriteOnce" ] storageClassName: standard resources: requests: storage: 1Gi
- 113. StatefulSet apiVersion: apps/v1 kind: StatefulSet metadata: name: sts-example spec: replicas: 2 revisionHistoryLimit: 3 selector: matchLabels: app: stateful serviceName: app updateStrategy: type: RollingUpdate rollingUpdate: partition: 0 template: <pod template> ● revisionHistoryLimit: The number of previous iterations of the StatefulSet to retain. ● serviceName: The name of the associated headless service; or a service without a ClusterIP.
- 114. Headless Service / # dig sts-example-0.app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> sts-example-0.app.default.svc.cluster.local +noall +answer ;; global options: +cmd sts-example-0.app.default.svc.cluster.local. 20 IN A 10.255.0.2 apiVersion: v1 kind: Service metadata: name: app spec: clusterIP: None selector: app: stateful ports: - protocol: TCP port: 80 targetPort: 80 $ kubectl get pods NAME READY STATUS RESTARTS AGE sts-example-0 1/1 Running 0 11m sts-example-1 1/1 Running 0 11m <StatefulSet Name>-<ordinal>.<service name>.<namespace>.svc.cluster.local / # dig app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> app.default.svc.cluster.local +noall +answer ;; global options: +cmd app.default.svc.cluster.local. 2 IN A 10.255.0.5 app.default.svc.cluster.local. 2 IN A 10.255.0.2 / # dig sts-example-1.app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> sts-example-1.app.default.svc.cluster.local +noall +answer ;; global options: +cmd sts-example-1.app.default.svc.cluster.local. 30 IN A 10.255.0.5
- 115. Headless Service / # dig sts-example-0.app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> sts-example-0.app.default.svc.cluster.local +noall +answer ;; global options: +cmd sts-example-0.app.default.svc.cluster.local. 20 IN A 10.255.0.2 apiVersion: v1 kind: Service metadata: name: app spec: clusterIP: None selector: app: stateful ports: - protocol: TCP port: 80 targetPort: 80 $ kubectl get pods NAME READY STATUS RESTARTS AGE sts-example-0 1/1 Running 0 11m sts-example-1 1/1 Running 0 11m <StatefulSet Name>-<ordinal>.<service name>.<namespace>.svc.cluster.local / # dig app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> app.default.svc.cluster.local +noall +answer ;; global options: +cmd app.default.svc.cluster.local. 2 IN A 10.255.0.5 app.default.svc.cluster.local. 2 IN A 10.255.0.2 / # dig sts-example-1.app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> sts-example-1.app.default.svc.cluster.local +noall +answer ;; global options: +cmd sts-example-1.app.default.svc.cluster.local. 30 IN A 10.255.0.5
- 116. Headless Service / # dig sts-example-0.app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> sts-example-0.app.default.svc.cluster.local +noall +answer ;; global options: +cmd sts-example-0.app.default.svc.cluster.local. 20 IN A 10.255.0.2 apiVersion: v1 kind: Service metadata: name: app spec: clusterIP: None selector: app: stateful ports: - protocol: TCP port: 80 targetPort: 80 $ kubectl get pods NAME READY STATUS RESTARTS AGE sts-example-0 1/1 Running 0 11m sts-example-1 1/1 Running 0 11m <StatefulSet Name>-<ordinal>.<service name>.<namespace>.svc.cluster.local / # dig app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> app.default.svc.cluster.local +noall +answer ;; global options: +cmd app.default.svc.cluster.local. 2 IN A 10.255.0.5 app.default.svc.cluster.local. 2 IN A 10.255.0.2 / # dig sts-example-1.app.default.svc.cluster.local +noall +answer ; <<>> DiG 9.11.2-P1 <<>> sts-example-1.app.default.svc.cluster.local +noall +answer ;; global options: +cmd sts-example-1.app.default.svc.cluster.local. 30 IN A 10.255.0.5
- 117. StatefulSet ● updateStrategy: Describes the method of updating the Pods based on the type. Valid options are OnDelete or RollingUpdate. ○ OnDelete: The new instance of the Pod is deployed ONLY after the current instance is deleted. ○ RollingUpdate: Pods with an ordinal greater than the partition value will be updated in one-by-one in reverse order. apiVersion: apps/v1 kind: StatefulSet metadata: name: sts-example spec: replicas: 2 revisionHistoryLimit: 3 selector: matchLabels: app: stateful serviceName: app updateStrategy: type: RollingUpdate rollingUpdate: partition: 0 template: <pod template>
- 118. StatefulSet spec: containers: - name: nginx image: nginx:stable-alpine ports: - containerPort: 80 volumeMounts: - name: www mountPath: /usr/share/nginx/html volumeClaimTemplates: - metadata: name: www spec: accessModes: [ "ReadWriteOnce" ] storageClassName: standard resources: requests: storage: 1Gi ● volumeClaimTemplates: Template of the persistent volume(s) request to use for each instance of the StatefulSet.
- 119. VolumeClaimTemplate volumeClaimTemplates: - metadata: name: www spec: accessModes: [ "ReadWriteOnce" ] storageClassName: standard resources: requests: storage: 1Gi $ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE www-sts-example-0 Bound pvc-d2f11e3b-18d0-11e8-ba4f-080027a3682b 1Gi RWO standard 4h www-sts-example-1 Bound pvc-d3c923c0-18d0-11e8-ba4f-080027a3682b 1Gi RWO standard 4h <Volume Name>-<StatefulSet Name>-<ordinal> Persistent Volumes associated with a StatefulSet will NOT be automatically garbage collected when it’s associated StatefulSet is deleted. They must manually be removed.
- 120. Job ● Job controller ensures one or more pods are executed and successfully terminate. ● Will continue to try and execute the job until it satisfies the completion and/or parallelism condition. ● Pods are NOT cleaned up until the job itself is deleted.*
- 121. Job ● backoffLimit: The number of failures before the job itself is considered failed. ● completions: The total number of successful completions desired. ● parallelism: How many instances of the pod can be run concurrently. ● spec.template.spec.restartPolicy: Jobs only support a restartPolicy of type Never or OnFailure. apiVersion: batch/v1 kind: Job metadata: name: job-example spec: backoffLimit: 4 completions: 4 parallelism: 2 template: spec: restartPolicy: Never <pod-template>
- 122. Job apiVersion: batch/v1 kind: Job metadata: name: job-example spec: backoffLimit: 4 completions: 4 parallelism: 2 template: spec: containers: - name: hello image: alpine:latest command: ["/bin/sh", "-c"] args: ["echo hello from $HOSTNAME!"] restartPolicy: Never $ kubectl describe job job-example Name: job-example Namespace: default Selector: controller-uid=19d122f4-1576-11e8-a4e2-080027a3682b Labels: controller-uid=19d122f4-1576-11e8-a4e2-080027a3682b job-name=job-example Annotations: <none> Parallelism: 2 Completions: 4 Start Time: Mon, 19 Feb 2018 08:09:21 -0500 Pods Statuses: 0 Running / 4 Succeeded / 0 Failed Pod Template: Labels: controller-uid=19d122f4-1576-11e8-a4e2-080027a3682b job-name=job-example Containers: hello: Image: alpine:latest Port: <none> Command: /bin/sh -c Args: echo hello from $HOSTNAME! Environment: <none> Mounts: <none> Volumes: <none> Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 52m job-controller Created pod: job-example-v5fvq Normal SuccessfulCreate 52m job-controller Created pod: job-example-hknns Normal SuccessfulCreate 51m job-controller Created pod: job-example-tphkm Normal SuccessfulCreate 51m job-controller Created pod: job-example-dvxd2 $ kubectl get pods --show-all NAME READY STATUS RESTARTS AGE job-example-dvxd2 0/1 Completed 0 51m job-example-hknns 0/1 Completed 0 52m job-example-tphkm 0/1 Completed 0 51m job-example-v5fvq 0/1 Completed 0 52m
- 123. CronJob An extension of the Job Controller, it provides a method of executing jobs on a cron-like schedule. CronJobs within Kubernetes use UTC ONLY.
- 124. CronJob ● schedule: The cron schedule for the job. ● successfulJobHistoryLimit: The number of successful jobs to retain. ● failedJobHistoryLimit: The number of failed jobs to retain. apiVersion: batch/v1beta1 kind: CronJob metadata: name: cronjob-example spec: schedule: "*/1 * * * *" successfulJobsHistoryLimit: 3 failedJobsHistoryLimit: 1 jobTemplate: spec: completions: 4 parallelism: 2 template: <pod template>
- 125. CronJob $ kubectl describe cronjob cronjob-example Name: cronjob-example Namespace: default Labels: <none> Annotations: <none> Schedule: */1 * * * * Concurrency Policy: Allow Suspend: False Starting Deadline Seconds: <unset> Selector: <unset> Parallelism: 2 Completions: 4 Pod Template: Labels: <none> Containers: hello: Image: alpine:latest Port: <none> Command: /bin/sh -c Args: echo hello from $HOSTNAME! Environment: <none> Mounts: <none> Volumes: <none> Last Schedule Time: Mon, 19 Feb 2018 09:54:00 -0500 Active Jobs: cronjob-example-1519052040 Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal SuccessfulCreate 3m cronjob-controller Created job cronjob-example-1519051860 Normal SawCompletedJob 2m cronjob-controller Saw completed job: cronjob-example-1519051860 Normal SuccessfulCreate 2m cronjob-controller Created job cronjob-example-1519051920 Normal SawCompletedJob 1m cronjob-controller Saw completed job: cronjob-example-1519051920 Normal SuccessfulCreate 1m cronjob-controller Created job cronjob-example-1519051980 apiVersion: batch/v1beta1 kind: CronJob metadata: name: cronjob-example spec: schedule: "*/1 * * * *" successfulJobsHistoryLimit: 3 failedJobsHistoryLimit: 1 jobTemplate: spec: completions: 4 parallelism: 2 template: spec: containers: - name: hello image: alpine:latest command: ["/bin/sh", "-c"] args: ["echo hello from $HOSTNAME!"] restartPolicy: Never $ kubectl get jobs NAME DESIRED SUCCESSFUL AGE cronjob-example-1519053240 4 4 2m cronjob-example-1519053300 4 4 1m cronjob-example-1519053360 4 4 26s
- 127. Concepts and Resources Storage ● Volumes ● Persistent Volumes ● Persistent Volume Claims ● StorageClass
- 128. Storage Pods by themselves are useful, but many workloads require exchanging data between containers, or persisting some form of data. For this we have Volumes, PersistentVolumes, PersistentVolumeClaims, and StorageClasses.
- 129. Volumes ● Storage that is tied to the Pod’s Lifecycle. ● A pod can have one or more types of volumes attached to it. ● Can be consumed by any of the containers within the pod. ● Survive Pod restarts; however their durability beyond that is dependent on the Volume Type.
- 130. Volume Types ● awsElasticBlockStore ● azureDisk ● azureFile ● cephfs ● configMap ● csi ● downwardAPI ● emptyDir ● fc (fibre channel) ● flocker ● gcePersistentDisk ● gitRepo ● glusterfs ● hostPath ● iscsi ● local ● nfs ● persistentVolume Claim ● projected ● portworxVolume ● quobyte ● rbd ● scaleIO ● secret ● storageos ● vsphereVolume Persistent Volume Supported
- 131. Volumes ● volumes: A list of volume objects to be attached to the Pod. Every object within the list must have it’s own unique name. ● volumeMounts: A container specific list referencing the Pod volumes by name, along with their desired mountPath. apiVersion: v1 kind: Pod metadata: name: volume-example spec: containers: - name: nginx image: nginx:stable-alpine volumeMounts: - name: html mountPath: /usr/share/nginx/html ReadOnly: true - name: content image: alpine:latest command: ["/bin/sh", "-c"] args: - while true; do date >> /html/index.html; sleep 5; done volumeMounts: - name: html mountPath: /html volumes: - name: html emptyDir: {}
- 132. Volumes ● volumes: A list of volume objects to be attached to the Pod. Every object within the list must have it’s own unique name. ● volumeMounts: A container specific list referencing the Pod volumes by name, along with their desired mountPath. apiVersion: v1 kind: Pod metadata: name: volume-example spec: containers: - name: nginx image: nginx:stable-alpine volumeMounts: - name: html mountPath: /usr/share/nginx/html ReadOnly: true - name: content image: alpine:latest command: ["/bin/sh", "-c"] args: - while true; do date >> /html/index.html; sleep 5; done volumeMounts: - name: html mountPath: /html volumes: - name: html emptyDir: {}
- 133. Volumes ● volumes: A list of volume objects to be attached to the Pod. Every object within the list must have it’s own unique name. ● volumeMounts: A container specific list referencing the Pod volumes by name, along with their desired mountPath. apiVersion: v1 kind: Pod metadata: name: volume-example spec: containers: - name: nginx image: nginx:stable-alpine volumeMounts: - name: html mountPath: /usr/share/nginx/html ReadOnly: true - name: content image: alpine:latest command: ["/bin/sh", "-c"] args: - while true; do date >> /html/index.html; sleep 5; done volumeMounts: - name: html mountPath: /html volumes: - name: html emptyDir: {}
- 134. Persistent Volumes ● A PersistentVolume (PV) represents a storage resource. ● PVs are a cluster wide resource linked to a backing storage provider: NFS, GCEPersistentDisk, RBD etc. ● Generally provisioned by an administrator. ● Their lifecycle is handled independently from a pod ● CANNOT be attached to a Pod directly. Relies on a PersistentVolumeClaim
- 135. PersistentVolumeClaims ● A PersistentVolumeClaim (PVC) is a namespaced request for storage. ● Satisfies a set of requirements instead of mapping to a storage resource directly. ● Ensures that an application’s ‘claim’ for storage is portable across numerous backends or providers.
- 136. Persistent Volumes and Claims Cluster Users Cluster Admins
- 137. apiVersion: v1 kind: PersistentVolume metadata: name: nfsserver spec: capacity: storage: 50Gi volumeMode: Filesystem accessModes: - ReadWriteOnce - ReadWriteMany persistentVolumeReclaimPolicy: Delete storageClassName: slow mountOptions: - hard - nfsvers=4.1 nfs: path: /exports server: 172.22.0.42 PersistentVolume ● capacity.storage: The total amount of available storage. ● volumeMode: The type of volume, this can be either Filesystem or Block. ● accessModes: A list of the supported methods of accessing the volume. Options include: ○ ReadWriteOnce ○ ReadOnlyMany ○ ReadWriteMany
- 138. PersistentVolume ● persistentVolumeReclaimPolicy: The behaviour for PVC’s that have been deleted. Options include: ○ Retain - manual clean-up ○ Delete - storage asset deleted by provider. ● storageClassName: Optional name of the storage class that PVC’s can reference. If provided, ONLY PVC’s referencing the name consume use it. ● mountOptions: Optional mount options for the PV. apiVersion: v1 kind: PersistentVolume metadata: name: nfsserver spec: capacity: storage: 50Gi volumeMode: Filesystem accessModes: - ReadWriteOnce - ReadWriteMany persistentVolumeReclaimPolicy: Delete storageClassName: slow mountOptions: - hard - nfsvers=4.1 nfs: path: /exports server: 172.22.0.42
- 139. PersistentVolumeClaim ● accessModes: The selected method of accessing the storage. This MUST be a subset of what is defined on the target PV or Storage Class. ○ ReadWriteOnce ○ ReadOnlyMany ○ ReadWriteMany ● resources.requests.storage: The desired amount of storage for the claim ● storageClassName: The name of the desired Storage Class kind: PersistentVolumeClaim apiVersion: v1 metadata: name: pvc-sc-example spec: accessModes: - ReadWriteOnce resources: requests: storage: 1Gi storageClassName: slow
- 140. PVs and PVCs with Selectors kind: PersistentVolume apiVersion: v1 metadata: name: pv-selector-example labels: type: hostpath spec: capacity: storage: 2Gi accessModes: - ReadWriteMany hostPath: path: "/mnt/data" kind: PersistentVolumeClaim apiVersion: v1 metadata: name: pvc-selector-example spec: accessModes: - ReadWriteMany resources: requests: storage: 1Gi selector: matchLabels: type: hostpath
- 141. PVs and PVCs with Selectors kind: PersistentVolume apiVersion: v1 metadata: name: pv-selector-example labels: type: hostpath spec: capacity: storage: 2Gi accessModes: - ReadWriteMany hostPath: path: "/mnt/data" kind: PersistentVolumeClaim apiVersion: v1 metadata: name: pvc-selector-example spec: accessModes: - ReadWriteMany resources: requests: storage: 1Gi selector: matchLabels: type: hostpath
- 142. PV Phases Available PV is ready and available to be consumed. Bound The PV has been bound to a claim. Released The binding PVC has been deleted, and the PV is pending reclamation. Failed An error has been encountered attempting to reclaim the PV.
- 143. StorageClass ● Storage classes are an abstraction on top of an external storage resource (PV) ● Work hand-in-hand with the external storage system to enable dynamic provisioning of storage ● Eliminates the need for the cluster admin to pre-provision a PV
- 144. StorageClass pv: pvc-9df65c6e-1a69-11e8-ae10-080027a3682b uid: 9df65c6e-1a69-11e8-ae10-080027a3682b 1. PVC makes a request of the StorageClass. 2. StorageClass provisions request through API with external storage system. 3. External storage system creates a PV strictly satisfying the PVC request. 4. provisioned PV is bound to requesting PVC.
- 145. StorageClass ● provisioner: Defines the ‘driver’ to be used for provisioning of the external storage. ● parameters: A hash of the various configuration parameters for the provisioner. ● reclaimPolicy: The behaviour for the backing storage when the PVC is deleted. ○ Retain - manual clean-up ○ Delete - storage asset deleted by provider kind: StorageClass apiVersion: storage.k8s.io/v1 metadata: name: standard provisioner: kubernetes.io/gce-pd parameters: type: pd-standard zones: us-central1-a, us-central1-b reclaimPolicy: Delete
- 146. Available StorageClasses ● AWSElasticBlockStore ● AzureFile ● AzureDisk ● CephFS ● Cinder ● FC ● Flocker ● GCEPersistentDisk ● Glusterfs ● iSCSI ● Quobyte ● NFS ● RBD ● VsphereVolume ● PortworxVolume ● ScaleIO ● StorageOS ● Local Internal Provisioner
- 148. Concepts and Resources Configuration ● ConfigMap ● Secret
- 149. Configuration Kubernetes has an integrated pattern for decoupling configuration from application or container. This pattern makes use of two Kubernetes components: ConfigMaps and Secrets.
- 150. ConfigMap ● Externalized data stored within kubernetes. ● Can be referenced through several different means: ○ environment variable ○ a command line argument (via env var) ○ injected as a file into a volume mount ● Can be created from a manifest, literals, directories, or files directly.
- 151. ConfigMap data: Contains key-value pairs of ConfigMap contents. apiVersion: v1 kind: ConfigMap metadata: name: manifest-example data: state: Michigan city: Ann Arbor content: | Look at this, its multiline!
- 152. ConfigMap Example apiVersion: v1 kind: ConfigMap metadata: name: manifest-example data: city: Ann Arbor state: Michigan $ kubectl create configmap literal-example > --from-literal="city=Ann Arbor" --from-literal=state=Michigan configmap “literal-example” created $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap file-example --from-file=cm/city --from-file=cm/state configmap "file-example" created All produce a ConfigMap with the same content! $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap dir-example --from-file=cm/ configmap "dir-example" created
- 153. ConfigMap Example apiVersion: v1 kind: ConfigMap metadata: name: manifest-example data: city: Ann Arbor state: Michigan $ kubectl create configmap literal-example > --from-literal="city=Ann Arbor" --from-literal=state=Michigan configmap “literal-example” created $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap file-example --from-file=cm/city --from-file=cm/state configmap "file-example" created All produce a ConfigMap with the same content! $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap dir-example --from-file=cm/ configmap "dir-example" created
- 154. ConfigMap Example apiVersion: v1 kind: ConfigMap metadata: name: manifest-example data: city: Ann Arbor state: Michigan $ kubectl create configmap literal-example > --from-literal="city=Ann Arbor" --from-literal=state=Michigan configmap “literal-example” created $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap file-example --from-file=cm/city --from-file=cm/state configmap "file-example" created All produce a ConfigMap with the same content! $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap dir-example --from-file=cm/ configmap "dir-example" created
- 155. ConfigMap Example apiVersion: v1 kind: ConfigMap metadata: name: manifest-example data: city: Ann Arbor state: Michigan $ kubectl create configmap literal-example > --from-literal="city=Ann Arbor" --from-literal=state=Michigan configmap “literal-example” created $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap file-example --from-file=cm/city --from-file=cm/state configmap "file-example" created All produce a ConfigMap with the same content! $ cat info/city Ann Arbor $ cat info/state Michigan $ kubectl create configmap dir-example --from-file=cm/ configmap "dir-example" created
- 156. Secret ● Functionally identical to a ConfigMap. ● Stored as base64 encoded content. ● Encrypted at rest within etcd (if configured!). ● Ideal for username/passwords, certificates or other sensitive information that should not be stored in a container. ● Can be created from a manifest, literals, directories, or from files directly.
- 157. Secret ● type: There are three different types of secrets within Kubernetes: ○ docker-registry - credentials used to authenticate to a container registry ○ generic/Opaque - literal values from different sources ○ tls - a certificate based secret ● data: Contains key-value pairs of base64 encoded content. apiVersion: v1 kind: Secret metadata: name: manifest-secret type: Opaque data: username: ZXhhbXBsZQ== password: bXlwYXNzd29yZA==
- 158. Secret Example apiVersion: v1 kind: Secret metadata: name: manifest-example type: Opaque data: username: ZXhhbXBsZQ== password: bXlwYXNzd29yZA== $ kubectl create secret generic literal-secret > --from-literal=username=example > --from-literal=password=mypassword secret "literal-secret" created $ cat secret/username example $ cat secret/password mypassword $ kubectl create secret generic file-secret --from-file=secret/username --from-file=secret/password Secret "file-secret" created All produce a Secret with the same content! $ cat info/username example $ cat info/password mypassword $ kubectl create secret generic dir-secret --from-file=secret/ Secret "file-secret" created
- 159. Secret Example apiVersion: v1 kind: Secret metadata: name: manifest-example type: Opaque data: username: ZXhhbXBsZQ== password: bXlwYXNzd29yZA== $ kubectl create secret generic literal-secret > --from-literal=username=example > --from-literal=password=mypassword secret "literal-secret" created $ cat secret/username example $ cat secret/password mypassword $ kubectl create secret generic file-secret --from-file=secret/username --from-file=secret/password Secret "file-secret" created All produce a Secret with the same content! $ cat info/username example $ cat info/password mypassword $ kubectl create secret generic dir-secret --from-file=secret/ Secret "file-secret" created
- 160. Secret Example apiVersion: v1 kind: Secret metadata: name: manifest-example type: Opaque data: username: ZXhhbXBsZQ== password: bXlwYXNzd29yZA== $ kubectl create secret generic literal-secret > --from-literal=username=example > --from-literal=password=mypassword secret "literal-secret" created $ cat secret/username example $ cat secret/password mypassword $ kubectl create secret generic file-secret --from-file=secret/username --from-file=secret/password Secret "file-secret" created All produce a Secret with the same content! $ cat info/username example $ cat info/password mypassword $ kubectl create secret generic dir-secret --from-file=secret/ Secret "file-secret" created
- 161. Secret Example apiVersion: v1 kind: Secret metadata: name: manifest-example type: Opaque data: username: ZXhhbXBsZQ== password: bXlwYXNzd29yZA== $ kubectl create secret generic literal-secret > --from-literal=username=example > --from-literal=password=mypassword secret "literal-secret" created $ cat secret/username example $ cat secret/password mypassword $ kubectl create secret generic file-secret --from-file=secret/username --from-file=secret/password Secret "file-secret" created All produce a Secret with the same content! $ cat info/username example $ cat info/password mypassword $ kubectl create secret generic dir-secret --from-file=secret/ Secret "file-secret" created
- 162. Injecting as Environment Variable apiVersion: batch/v1 kind: Job metadata: name: cm-env-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“printenv CITY”] env: - name: CITY valueFrom: configMapKeyRef: name: manifest-example key: city restartPolicy: Never apiVersion: batch/v1 kind: Job metadata: name: secret-env-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“printenv USERNAME”] env: - name: USERNAME valueFrom: secretKeyRef: name: manifest-example key: username restartPolicy: Never
- 163. Injecting as Environment Variable apiVersion: batch/v1 kind: Job metadata: name: cm-env-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“printenv CITY”] env: - name: CITY valueFrom: configMapKeyRef: name: manifest-example key: city restartPolicy: Never apiVersion: batch/v1 kind: Job metadata: name: secret-env-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“printenv USERNAME”] env: - name: USERNAME valueFrom: secretKeyRef: name: manifest-example key: username restartPolicy: Never
- 164. Injecting in a Command apiVersion: batch/v1 kind: Job metadata: name: cm-cmd-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“echo Hello ${CITY}!”] env: - name: CITY valueFrom: configMapKeyRef: name: manifest-example key: city restartPolicy: Never apiVersion: batch/v1 kind: Job metadata: name: secret-cmd-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“echo Hello ${USERNAME}!”] env: - name: USERNAME valueFrom: secretKeyRef: name: manifest-example key: username restartPolicy: Never
- 165. Injecting in a Command apiVersion: batch/v1 kind: Job metadata: name: cm-cmd-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“echo Hello ${CITY}!”] env: - name: CITY valueFrom: configMapKeyRef: name: manifest-example key: city restartPolicy: Never apiVersion: batch/v1 kind: Job metadata: name: secret-cmd-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“echo Hello ${USERNAME}!”] env: - name: USERNAME valueFrom: secretKeyRef: name: manifest-example key: username restartPolicy: Never
- 166. Injecting as a Volume apiVersion: batch/v1 kind: Job metadata: name: cm-vol-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“cat /myconfig/city”] volumeMounts: - name: config-volume mountPath: /myconfig restartPolicy: Never volumes: - name: config-volume configMap: name: manifest-example apiVersion: batch/v1 kind: Job metadata: name: secret-vol-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“cat /mysecret/username”] volumeMounts: - name: secret-volume mountPath: /mysecret restartPolicy: Never volumes: - name: secret-volume secret: secretName: manifest-example
- 167. Injecting as a Volume apiVersion: batch/v1 kind: Job metadata: name: cm-vol-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“cat /myconfig/city”] volumeMounts: - name: config-volume mountPath: /myconfig restartPolicy: Never volumes: - name: config-volume configMap: name: manifest-example apiVersion: batch/v1 kind: Job metadata: name: secret-vol-example spec: template: spec: containers: - name: mypod image: alpine:latest command: [“/bin/sh”, “-c”] args: [“cat /mysecret/username”] volumeMounts: - name: secret-volume mountPath: /mysecret restartPolicy: Never volumes: - name: secret-volume secret: secretName: manifest-example
- 168. Lab - github.com/mrbobbytables/k8s-intro-tutorials/blob/master/configuration Using ConfigMaps and Secrets
- 170. Where to go From Here
- 172. Slack Kubernetes slack.k8s.io 70,000+ users 300+ public channels CNCF slack.cncf.io 8,200+ users 70+ public channels 07/2019
- 173. Other Communities ● Official Forum https://discuss.kubernetes.io ● Subreddit https://reddit.com/r/kubernetes ● StackOverflow https://stackoverflow.com/questions/tagged/kubernetes
- 174. Meetups Kubernetes meetup.com/topics/kubernetes/ 850+ groups 380,000+ members CNCF meetups.cncf.io 200+ groups 120,000+ members 45+ countries 07/2019
- 175. Conventions Europe: March 30 – April 2, 2020 Amsterdam, Netherlands China: TBD North America: November 18 - 21, 2019 San Diego, CA 07/2019
- 176. GitHub
- 177. SIGs ● Kubernetes components and features are broken down into smaller self-managed communities known as Special Interest Groups (SIG). ● Hold weekly public recorded meetings and have their own mailing lists and slack channels.
- 179. Working Groups ● Similar to SIGs, but are topic focused, time-bounded, or act as a focal point for cross-sig coordination. ● Hold scheduled publicly recorded meetings in addition to having their own mailing lists and slack channels.
- 181. Links ● Free Kubernetes Courses https://www.edx.org/ ● Interactive Kubernetes Tutorials https://www.katacoda.com/courses/kubernetes ● Learn Kubernetes the Hard Way https://github.com/kelseyhightower/kubernetes-the-hard-way ● Official Kubernetes Youtube Channel https://www.youtube.com/c/KubernetesCommunity ● Official CNCF Youtube Channel https://www.youtube.com/c/cloudnativefdn ● Track to becoming a CKA/CKAD (Certified Kubernetes Administrator/Application Developer) https://www.cncf.io/certification/expert/ ● Awesome Kubernetes https://ramitsurana.gitbooks.io/awesome-kubernetes/content/
- 182. Questions?