Hands-On Introduction to Kubernetes at LISA17

S1 Hands-On Introduction to
Kubernetes
at in SF
Sunday, October 29th 9:00 am–12:30 pm
#LISA17
bit.ly/lisa17-k8s

presented by , Developer Advocate at Red Hat@ryanj

Administration
1.
2.
3.
4.
5.
Introduction
Workshop Setup
Kubernetes Basics
Learn five K8s Primitives
Kubernetes Architecture
Local Development with
Minikube
Wrap-up

Intro Survey / Who are you?
1. Are you doing anything with containers today?
2. Do you have any experience using Kubernetes?
3. Do you consider yourself to be basically proficient with the
kubectl cli tool?
4. Can you name five basic primitives or resource types?
5. Can you name five architectural components provided by
Kubernetes?

LISA17 S1 Training Prep
Bring a laptop with the following items pre-installed:
1.
2.
3.
4.
kubectl
minikube
docker
git

Install kubectl
Installation on linux/amd64:
Installation on macOS:
For other platforms, consult the o icial
To verify kubectl availability, try running:
curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s
curl -LO https://storage.googleapis.com/kubernetes-release/release/$(curl -s
kubectl setup guide
kubectl help

Install minikube
Installation on linux/amd64:
Installation on macOS:
For other platforms, see the
Optionally, customize your cluster's memory or cpu allocation:
to verify minikube availability:
curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/min
curl -Lo minikube https://storage.googleapis.com/minikube/releases/latest/min
minikube release notes
minikube config set memory 4096
minikube config set cpus 2
minikube version

Minikube Basics
minikube provides an easy way to run Kubernetes locally:
When you are done, halt the VM to free up system resources:
Need a fresh start? Delete your VM instance with:
minikube start
minikube stop
minikube delete

Minikube troubleshooting
If your minikube environment does not boot correctly:
1. Minikube requires an OS virtualization back-end
2. Most OSes include some support for virtualization
3. You can use the flag to select a specific virt
provider
Check the project for more information about
Still stuck? Consider signing up for OpenShi Starter or GKE:
bit.ly/k8s-gcloud
--vm-driver
minikube start --vm-driver=virtualbox
README supported
virtualization plugins

Install docker
Download and install a binary from
Or, use a package manager to install:
To verify docker availability:
To , run:
the docker store
brew install docker
docker version
reference minikube's docker daemon from your host
eval $(minikube docker-env)

Install git
Install git using the instructions here:
To verify git availability, run:
https://git-scm.com/book/en/v2/Getting-Started-Installing-Git
git version

Ready?
Verify that your local Kubernetes environment is ready by running:
The output should include your kubectl version info, and the
release version of the kubernetes API server (when available)
kubectl version

Kubernetes Command-Line Basics
with kubectl

Kubernetes is...
1. An open source platform for running container-based distributed
solutions, featuring a modular, HA systems architecture
2. The best way to actively manage distributed solutions at scale,
based on years of industry expertise (Google-scale experience)
3. An extensible distributed-solutions modeling language with a
huge community following
4. A multi-vendor e ort to eliminate cloud lock-in through the
adoption of "cloud native" solutions (capable of runnning on any
infrastructure)

Kubernetes provides…
An API
API object primitives include the following attributes:
*mostly true
kind
apiVersion
metadata
spec
status

Basic K8s Terminology
1.
2.
3.
4.
5.
node
pod
service
deployment
replicaSet

Node
A node is a host machine (physical or virtual) where containerized
processes run.
Node activity is managed via one or more Master instances.

Try using kubectl to list resources by type:
Request the same info, but output the results as structured yaml:
Fetch an individual resource by type/id, output as json:
View human-readable API output:
kubectl get nodes
kubectl get nodes -o yaml
kubectl get node/minikube -o json
kubectl describe node/minikube

Observations:
Designed to exist on multiple machines (distributed
system)
high availability of nodes
platform scale out
The API ambidextriously supports both json and yaml

Pod
A group of one or more co-located containers. Pods represent your
minimum increment of scale.
"Pods Scale together, and they Fail together"
@theSteve0

List resources by type:
Create a new resource based on a json object specification:
Fetch a resource by type and id, output the results as yaml:
Notice any changes?
kubectl get pods
curl https://raw.githubusercontent.com/ryanj/metrics-k8s/master/pod.json
kubectl create -f https://raw.githubusercontent.com/ryanj/metrics-k8s/master/
kubectl get pods
kubectl get pod metrics-k8s -o yaml

Observations:
pods are scheduled to be run on nodes
asyncronous fulfilment of requests
declarative specifications
automatic health checks, lifecycle management for containers
(processes)

Service
Services (svc) establish a single endpoint for a collection of
replicated pods, distributing inbound tra ic based on label
selectors
In our K8s modeling language they represent a load balancer. Their
implementation o en varies per cloud provider

Contacting your App
Expose the pod by creating a new service (or "loadbalancer"):
Contact your newly-exposed pod using the associated service id:
Schedule a pod to be deleted:
Contact the related service. What happens?:
Delete the service:
kubectl expose pod/metrics-k8s --port 2015 --type=NodePort
minikube service metrics-k8s
kubectl delete pod metrics-k8s
kubectl delete service metrics-k8s

Observations:
"service" basically means "loadbalancer"
Pods and Services exist independently, have disjoint
lifecycles

Deployment
A deployment helps you specify container runtime requirements
(in terms of pods)

Create a specification for your deployment:
View the generated deployment spec file:
Bug?:You may need to edit this file, adding "---" (on it's own line)
between resource 1 and resource 2 for a workaround.
Can you think of another way to fix this issue? json compatible?
kubectl run metrics-k8s --image=quay.io/ryanj/metrics-k8s
--expose --port=2015 --service-overrides='{ "spec": { "type": "NodePort" } }'
--dry-run -o yaml > deployment.yaml
cat deployment.yaml

Create a new resource based on your yaml specification:
Connect to your new deployment via the associated service id:
kubectl create -f deployment.yaml
kubectl get po,svc

Replication
Scale up the metrics-k8s deployment to 3 replicas:
List pods:
kubectl scale deploy/metrics-k8s --replicas=3
kubectl get po

Edit deploy/metrics-k8s, setting spec.replicas to 5:
Save and quit. What happens?
kubectl edit deploy/metrics-k8s -o json
kubectl get pods

AutoRecovery
Watch for changes to pod resources:
In another terminal, delete several pods by id:
What happend? How many pods remain?
kubectl get pods --watch
kubectl delete pod $(kubectl get pods | grep ^metrics-k8s | cut -f1 -s -d' '
kubectl get pods

Observations:
Use the --dry-run flag to generate new resource
specifications
A deployment spec contains a pod spec

ReplicaSet
A replicaset provides replication and lifecycle management for
a specific image release

Watch deployments (leave this running until the 'cleanup' section):
View the current state of your deployment:
kubectl get deploy --watch

Rollouts
Update your deployment's image spec to rollout a new release:
Reload your browser to view the state of your deployment
kubectl set image deploy/metrics-k8s metrics-k8s=quay.io/ryanj/metrics-k8s:v1
kubectl get rs,deploy

Rollbacks
View the list of previous rollouts:
Rollback to the previous state:
Reload your browser to view the state of your deployment
kubectl rollout history deploy/metrics-k8s
kubectl rollout undo deployment metrics-k8s

Cleanup
Cleanup old resources if you don't plan to use them:
Close any remaining --watch listeners
kubectl delete service,deployment metrics-k8s

Observations:
The API allows for watch operations (in addition to get, set, list)
ReplicaSets provide lifecycle management for pod resources
Deployments create ReplicaSets to manage pod replication per
rollout (per change in podspec: image:tag, environment vars)

Kubernetes Architecture
adapted for minikube

Kubernetes is designed ...
1. for managing distributed solutions at scale, based on years of
industry expertise (Google-scale experience)
2. for high availabilty of the control plane and user workloads
(when using pod replication), avoiding most single points of
failure
3. with a modular control plane architecture, allowing many peices
to be replaced without disrupting workload availability
4. to persist all of it's internal platform state within an etcd
database

etcd
distributed key-value store
implements the RAFT consensus
protocol

CAP theorum
1. Consistency
2. Availability
3. Partition
tolerance
etcd is "CA"

Degraded Performance
Fault tolerance sizing chart:

play.etcd.io
play.etcd.io/play

Kubernetes API
gatekeeper for etcd (the only way to access the
db)
not required for pod uptime

API outage simulation
Example borrowed from
:
Brandon Philips' "Fire Drills" from OSCON
2016
https://github.com/philips/2016-OSCON-containers-at-scale-with-
Kubernetes#fire-drills

Create a pod and a service. Verify that the service is responding.
ssh into minikube, kill the control plane:
Use kubectl to list pods:
The API server is down!
Reload your service. Are your pods still available?
kubectl run metrics-k8s --image=quay.io/ryanj/metrics-k8s
minikube ssh
ps aux | grep "localkube"
sudo killall localkube
logout
kubectl get pods
The connection to the server mycluster.example.com was refused - did you spec

Kubelet
Runs on each node, listens to the API for new items with a matching
NodeName

Kubernetes Scheduler
Assigns workloads to Node machines

Bypass the Scheduler
Create two pods:
View events:
Did both pods get scheduled? run?
kubectl create -f https://raw.githubusercontent.com/ryanj/metrics-k8s/master/
kubectl create -f https://gist.githubusercontent.com/ryanj/893e0ac5b3887674f8
kubectl get events

CRI
containerd
(docker)
cri-o
rkt
compatible with OCI image spec., runtime

K8s Controllers
Controllers work to regulate the declarative nature of the platform
state, reconsiling imbalances via a basic control loop
Kubernetes allows you to introduce your own custom controllers!
https://kubernetes.io/docs/admin/kube-controller-manager/

Interaction Diagram
(copied from blog.docker.com)

Local Development
with
minikube

Kubernetes provides portable abstractions for working with
distributed solitions:
1. standardized packaging (containers, volumes,
pods)
2. load balancing (services)
3. scaling automation (replica sets)
Need any of these for local development?

Why run K8s locally?
As web development is increasingly being carried out using
container-based microservices:
1. ability to o er reproducible development environments
reduce onboarding time for new devs
2. minimize deltas between dev and prod environments
fewer surprises when promoting code leads to faster velocity
3. decentralize your release pipeline, allow CI test suites to be run
locally
provide functional / systems-integration feedback earlier in
the dev lifecycle
4. potenial for fully o line development
<expanding brain meme>

Local Development Checklist:
1. - show someone new how to run the :latest
release
2. - review changes and iterate on a solution
3. - build and deploy
4. - git push
onboarding
preview changes
test changes
promote changes

Onboarding - Yesterday's Jam
1. git clone https://github.com/ryanj/metrics-
k8s
2. cd metrics-k8s
3. npm install
4. npm start

Onboarding - Add K8s
Generate kubernetes deployment and service specifications,
both named metrics-review:
kubectl run metrics-review --image=quay.io/ryanj/metrics-k8s
--dry-run -o yaml > metrics-review.yaml

Onboarding - deploy :latest
Test your generated spec:
Minikube users will be able to open the resulting service in their
browser by running:
kubectl create -f metrics-review.yaml
minikube service metrics-review

Preview - local files
First, share your local clone of metrics-k8s with minikube:
minikube mount $(pwd):/var/www/html

Preview - hostPath
Next, produce a new deployment spec that includes (minimal)
support for live development workflows:
1. cp metrics-review.yaml metrics-
dev.yaml
2. replace metrics-review with metrics-dev
(global)
3. Add a hostPort volume to access your local repo:
spec:
containers:
- image: quay.io/ryanj/metrics-k8s
name: metrics-dev
ports:
- containerPort: 2015
resources: {}
+ volumeMounts:
+ - mountPath: /var/www/html
+ name: metrics-src
+ volumes:
+ - name: metrics-src
+ hostPath:

Preview
The resulting file should look just like the included
file from the metrics-k8s git repo.
Try launching it with:
metrics-
dev.yaml
kubectl create -f metrics-dev.yaml

Preview
Verify that any changes written to your local repo become
immediately visible when reloading your browser window:
1. view your latest
2. make a change to
index.html
3. reload your browser
minikube service metrics-dev

Test - Rollout
1. Verify that
2. Run a build
3. Update metrics-review.yaml, setting the container
image to:
4. Apply the changes locally:
5. Check your latest before promoting:
your docker-env is configured for minikube
docker build . -t yourname/metrics-k8s:v1
yourname/metrics-k8s:v1
kubectl apply -f metrics-review.yaml
minikube service metrics-review

Promoting Changes
1. git push?
2. send PR?
3. next steps TBD / handled by CI
suite

Resources
1. Training materials to-go:
2. Home:
3. Docs:
4. Community:
5. eBook:
6. eBook:
7. eBook:
8. eBook:
bit.ly/k8s-workshops
kubernetes.io
K8s documentation
K8s Special Interest Groups (SIGs)
Kubernetes: Scheduling the Future at Cloud Scale
Docker Security: Using Containers Safely in
Production
Microservices vs. Service-Oriented Architecture
OpenShi for Developers

Exit Survey
1. Have you ever developed using containers?
2. Do you have any experience using Kubernetes?
3. Do you consider yourself to be basically proficient with the
kubectl cli tool?
4. Can you name five basic primitives or resource types?
5. Can you name five pieces of k8s architecture?
6. Are you prepared to onboard a new web dev?

Congratulations!
on completing the
[S1] Hands-on Intro to Kubernetes
tutorial at #LISA17 in SF
Please remember to complete your tutorial evaluation!
bit.ly/lisa17-k8s

Hands-On Introduction to Kubernetes at LISA17

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