deployment.md

deployment

• when a new deployment is created a rollout is performed.
  • each rollout for same deployment is a revision
  • when next rollout is created it'll be revision 2 and so on..
  • this keeps tracks of deployments
  • allows for easy rollback if needed using revisions
• use [[kubectl]] to apply a yaml definition with changes to the deployment
  • a revision is auto created
• kubectl set command can be used to update the deployment imperatively

deployment strategy

• available strategies
  • recreate - takes down the entire deployment and redeploy with new updates
  • rolling - default strategy. takes down a pod with older version and brings up new pods, one by one to avoid downtime.

rolling upgrades

• a [[replicaset]] is created with new pods and replaced one by one and the old replicaset is removed when the rollout is complete and vice versa for rollbacks.

commands

rollout status deployment/my-deployment - shows the status of the deployment rollout history deployment/my-deployment - shows the revisions/history of the deployment rollout undo deployment/my-deployment - rollback the last deployment set image deployment/mydeployment nginx=nginx:1.9.1 - changes the image of the deployment imperatively

definition

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80