Kubernates : An Small introduction for Beginners by Rajiv Vishwkarma
- 2. Agenda • History • What is Kubernetes • Why Kubernetes • Architecture • Architecture Components • Kubelet • Kubectl • KubeADM • kubefed • Minikube • Helm • Rancher • Learning and Practice
- 3. Kubernetes ( K8S ) • Google developed an internal system called BORG then they have changed its name OMEGA to deploy and manage 1000 google applications. • 2014 it became Open-Source and donated it to CNCF (Cloud Native Computing Foundation). • brings K8s very First. • Then adopted by Azure. • AWS brings K8S very later.
- 4. What Is Kubernetes? Project 7 - Google
- 5. • Kubernetes is an open-source container orchestration platform • it automates • Container Deployment, • Container Scaling. • Load balancing ( eg. - all containers must have equal number of request) • It also schedules, Run, Manage containers which are running on physical virtual or cloud machines (based on our requirement like we want to create 200 containers after 2 hours, delete 100 containers after 3 hrs ) • All top cloud providers support K8S. • It creates cluster of containers. • It provides scalability to containers. • It provides High Availability to containers. • Kubernetes Doesn’t create Images. What Is Kubernetes? Cont….
- 6. Features of Kubernetes? • Containers cannot communicate each other. • Auto scaling (Vertical and Horizontal) • Load Balancing • Auto Healing • Platform independent • Fault Tolerance • Rollback • Health Monitoring of Containers • Health Monitoring of Pods • Batch Execution(One time, Sequential, Parallel)
- 7. Why Kubernetes? Cont…. • With Monolithic Apps Scaling is very Hard to manage • Monolithic Apps are difficult to manage. • High Availability is not there for Monolithic Apps. • All the above issues resolved via microservices. Therefore Monolithic apps are replaced by Microservices. • Eg 1 – we want to create 100 numbers of containers from the same image – we cannot run docker run command these many number of times manually • Even though if it is possible but if we want to create 200-300 containers of each image of an application that is having 40/50 images this work is very hard to manage manually. • Eg 2 - suppose I need to reduce the number of containers based on the usage even though we cannot delete these many number of containers. • It means scaling should be automated. (based on users access). • That is done by kubernates. • Kubernetes supports all Docker, Rocket, ContainerD
- 8. Why Kubernetes? Cont…. • Docker Swarm does the things what Kubernetes Does. • But Docker Swarm only manages Docker Containers only, while K8S Supports all kinds of Containers(Docker/Rocker/ContainerD). • Kubernetes is more popular, it is better than Docker-Swarm. • Market of Docker Swarm 11% • While market share of Kubernetes is 57%.
- 11. Architecture Components – Master Node / Controller Manager • Control Manager • Handles what should be there or what should not be there. This is the component that maintains the balance between Actual state and desired state. • Logically, each controller is a separate process, but to reduce complexity, they are all compiled into a single binary and run in a single process. • These controllers include: • Node Controller: Responsible for noticing and responding when nodes go down. • Replication Controller: Responsible for maintaining the correct number of pods for every replication controller object in the system. • Endpoints Controller: Populates the Endpoints object (that is, it joins Services and Pods). • Service Account and Token Controllers: Create default accounts and API access tokens for new namespaces.
- 12. Architecture Components – Master Node / Controller Manager • API Server • Most Important component(other components talk to each other via API Server) • The API server is a component of the Kubernetes control plane that exposes the Kubernetes API. The API server is the front end for the Kubernetes control plane. • ETCD • Database / Storage system. (Eg. It keeps the record of how many instances are there and how many are required ). • Consistent and highly-available key value store used as Kubernetes' backing store for all cluster data. • KubeScheduler • Controller manager gives the instruction to Kube Scheduler to perform any task. (Main Action is done by Kube Schedular ) • Control plane component that watches for newly created Pods with no assigned node, and selects a node for them to run on.
- 13. • Pod – • Basic Component /Logical Unit of K8s, • A pod is a group of one or more containers, • Inside a pod containers are tightly coupled because they share access to the same volume. • If pod gets corrupted/destroyed then it never repaired, always a new pod is created. A Cluster is a group of Nodes. A Cluster is a group of Master and worker nodes. Architecture Components – Worker Node/Minion
- 14. • Kubelet • Control the pods, informs master about the pod Health / and status. Like – • how many Containers should be there in the pod, • what should be there in the pod. • This is the only component/Agent that communicates wth API Server on Master Node • It Listens to Kubernetes Master. And use port 10255 to run. • It sends/shares Pod Creation status success/failure to the master. • Kube Proxy – Handles Networking related work. • Assign IP Address to each POD (IP Address never assigned to Container, it always assigned to POD) • If two POD wants to communicate each other then it is done via Kube-Proxy. • Id pod restarts then assigned IP Address will be changed. • Container Engine – Docker / ContainerD / Rocket • Works with Kubelet • Pulls Images, • Start/Stop Containers. Architecture Components – Worker Node/Minion
- 15. Kubelet • Kubelet is the primary “node agent” that runs on each node and is used to register the nodes in the Kubernetes cluster through the API server. • After a successful registration, the primary role of kubelet is to create pods and listen to the API server for instructions.
- 16. Kubectl • The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. • You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs.
- 17. Kubeadm • Kubeadm is a tool built to provide kubeadm init and kubeadm join as best- practice "fast paths" for creating Kubernetes clusters. • It is the command to bootstrap the cluster. • kubeadm init to bootstrap a Kubernetes control- plane node • kubeadm join to bootstrap a Kubernetes worker node and join it to the cluster.
- 18. Kubefed • KubeFed (Kubernetes Cluster Federation) • Allows you to use a single Kubernetes cluster to coordinate multiple Kubernetes clusters. • It can deploy multiple- cluster applications in different regions and design for disaster recovery.
- 19. Minikube • It is a utility you can use to run Kubernetes (k8s) on our local machine. • It creates a single node cluster contained in a virtual machine (VM). • This cluster lets you demo Kubernetes operations without requiring the time and resource- consuming installation of full- blown K8s.
- 21. Helm • K8S can become very complex with all the objects(Config Maps, Services, Pods, Persistence Volumes, … ) that we need to handle and multiply by the number of releases that we want. • All the above objects will be managed easily by HELM. • HELM is a simple way of packaging all of them into One simple application. It also advertising what we can configure. • Helm is a package manager for Kubernetes • With Helm the Deploy, Manage, and Maintain process will become easier. • Helm fills the need to quickly and reliably provision container applications through easy install, update, and removal. • Helm is the K8s equivalent of yum or apt commands. • If we want to package release over 1.0 and make only certain parts configurable , we can do that. • With version 2.0 we can configure certain more parts configurable. • We can simply install by One Click, or we can configure it suite our needs.
- 22. Rancher (RKE) • It’s a Kubernetes installer that provides a UI and API. • The users can easily access Kubernetes clusters. • They can also access KubeCTL, which is an integrated tooling layer providing log management, CI/CD, alerting, etc. • It is a lightweight Kubernetes installer. It can launch Kubernetes on any computers, including: A. Bare-metal servers B. On-premise virtual machines C. Virtual machines hosted by an infrastructure provider Rancher is ideal for firms seeking a proven multi-cloud container management platform available on a wide variety of cloud platforms and edge environments.
- 23. Learning / Practice • Kubernetes Playground • Play with Kubernetes • Play with Kubernetes Classroom • Google Kubernete Engine (GKE) • Azure Kubernete Services (AKS) • Amazon EKS (Elastic Kubernete Service) • MiniKube • KubeADM
- 24. Thanks to the below listed websites • https://www.researchgate.net/figure/Kubernetes-architecture_fig1_320248964 • https://heranonazure.wordpress.com/2018/10/09/install-minikube/ • https://www.simplilearn.com/tutorials/kubernetes-tutorial/kubernetes-architecture • https://rancher.com/why-rancher/ • https://dockerlabs.collabnix.com/kubernetes/beginners/what-is-kubect.html • https://medium.com/edureka/kubernetes-vs-docker-45231abeeaf1 • https://redblink.com/install-rancher-kubernetes-cluster/#What_is_a_Rancher
- 25. Thank you