Notes

Kubernetes

Kubernetes is an open-source container orchestration system for automating software deployment, scaling, and management.

Commands

Fetching version
```
  kubectl version
```
Fetching details of types (Pods, Services, Deployments, ReplicaSets)
```
  kubectl get <type>
```
Fetching details of all objects
```
  kubectl get all
```
fetching pods with more details(including ip addresses)
```
kubectl get pods -o wide
```

Running a pod

  kubectl run <name> --image=<image_name>

Creating an object using a yaml file
```
  kubectl create -f <file_name>
```

Update or Apply Changes

  kubectl apply -f <file_name>
  #           (or)
  kubectl replace -f <file_name>

Fetching details of particular object
```
  kubectl describe <type> <name>
```

Scaling the objects

  kubectl scale --replicas=6 <type> <name>

Deleting
```
  kubectl delete <type> <name>
```
Updating the properties in YAML format
```
  kubectl edit <type> <name>
```

YAML Definitions

Pod definitions

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
  labels:
    app: my-app
spec:
  containers:
    - name: my-container
      image: nginx:latest
      ports:
        - containerPort: 80

ReplicaSet definitions

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: example-replicaset
  labels:
    app: my-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
      - name: my-container
        image: nginx:latest
        ports:
        - containerPort: 80

Deployment definitions

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-deployment
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: my-container
          image: nginx:latest
          ports:
            - containerPort: 80

Service definitions

apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: my-app
  ports:
    - protocol: TCP
      port: 80
      targetPort: 80
  type: ClusterIP

Types: ClusterIP, NodePort, LoadBalancer

Explained about Services in detail Here