Basics of kubernetes with basic examples.

1. kubernet
es

2. THE NEED FOR CONTAINER
ORCHESTRATION
 Docker
 packaging, deploying and running containerized application
 applications are independent of the underlying OS architecture.
 Docker itself can be used to manage a few containers running on a
fewer machines.
 Production applications deploy containers on a large scale on
hundreds of machines.

3. THE NEED FOR CONTAINER
ORCHESTRATION
PHYSICAL INFRASTRUCURE
VM VM VM VMVM VM VMVM
CLUSTER CLUSTER
CLUSTERCLUSTERCLUSTER
CLUSTER MANAGER

4. WHAT IS KUBERNETES
 A subset of an internal Google project called Borg.
 Decouples application from machines through containers.
 Maintains and tracks the global view of the cluster.
 Distributed architecture with master and multiple worker nodes.
 Developed in Go language.
 Automate the scaling and distribution of applications.

5. K8S FEATURES
 Horizontal scaling – with command or based on CPU usage.
 Self-healing – restart containers that fail or don`t respond to health
check. Replaces and reschedules containers when nodes die.
 Automating binpacking – placing the containers based on their
resource requirements thus saving system resource.
 Automated rollouts and rollbacks - If something goes wrong,
Kubernetes will rollback the changes.
 Storage orchestration – mount the storage system of your choice
from local storage or AWS or from a network storage system.

6. KUBERNETES ARCHITECTURE
XML file
JSON file
YAML file

7. KUBERNETES COMPONENTS
 Master - coordinates the cluster
 Cluster - set of physical or virtual machines and other infrastructure
resources used by Kubernetes to run your applications.
 Nodes – hosts that run kubernetes applications.
 Pod - a co-located group of containers and volumes. Unit of
deployment.
 Label - a key/value pair for identification.
 Replication Controller – ensures/maintains availability and
scalability.
 etcd – maintains state.

8. CREATING A CLUSTER
A k8s cluster consists of two types of resources
 The Master coordinates the cluster
 Nodes are the workers that runs application.
 The nodes communicate with the master using the Kubernetes
API, which the master exposes.

9. CREATE A DEPLOYMENT
 A Deployment is responsible for
creating and updating instances of application.
 The Deployment controller replaces an instance
if the Node hosting it goes down or it is deleted.

10. PODS AND NODES
 A Pod is a group of one or more application
containers and includes shared storage (volumes),
IP address and information about how to run them.

11. PODS AND NODES
 Every Kubernetes Node runs at least:
Kubelet, a process responsible for communication
between the Kubernetes Master and the Nodes
A container runtime (like Docker, rkt).

12. SERVICES
Provides external access to a single
or group of pods.

13. SCALING

14. BASIC COMMANDS
 Cluster
minikube start
kubectl cluster-info
kubectl get nodes
 Deployment
kubectl run kubernetes-bootcamp --image=docker.io/jocatalin/kubernetes-
bootcamp:v1 --port=8080
kubectl get deployments
 Pods
kubectl get pods
kubectl describe pods
kubectl proxy

15. BASIC COMMANDS
 Pods
export POD_NAME=$(kubectl get pods -o go-template --template '{{range
.items}}{{.metadata.name}}{{"n"}}{{end}}')
echo Name of the Pod: $POD_NAME
kubectl logs $POD_NAME
kubectl exec -ti $POD_NAME bash
 Services
kubectl expose deployment/kubernetes-bootcamp --type="NodePort" --port 8080
kubectl get services
kubectl describe services/kubernetes-bootcamp
export NODE_PORT=$(kubectl get services/kubernetes-bootcamp -o go-
template='{{(index .spec.ports 0).nodePort}}') echo NODE_PORT=$NODE_PORT
minikube service kubernetes-bootcamp

16. BASIC COMMANDS
 Scaling
kubectl scale deployments/kubernetes-bootcamp --replicas=4
kubectl get deployments
kubectl get pods -o wide
 Updating image
kubectl set image deployments/kubernetes-bootcamp kubernetes-
bootcamp=jocatalin/kubernetes-bootcamp:v2
minikube service kubernetes-bootcamp
kubectl get pods

17. REFERENCES
https://kubernetes.io/docs/tutorials/kubernetes-basics/ -
Interactive tutorial
https://kubernetes.io/docs/tutorials/stateless-application/hello-
minikube/