15-Deployments.md

Deployments

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In this section, we will take a look at kubernetes deployments

Deployment is a kubernetes object.

• The Deployment provides us with the capability to upgrade the underline instances seemlessly using Rolling updates, Undo Changes and Pause and Resume Changes as required.

  

How do we create deployment?

• As with the previous components we created a defination file, the content of the deployment defination file is similar to replicaset defination file. Except with the kind which is now going to be Deployment.

    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: myapp-deployment
      labels:
        app: myapp
        type: front-end
    spec:
     template:
        metadata:
          name: myapp-pod
          labels:
            app: myapp
            type: front-end
        spec:
         containers:
         - name: nginx-container
           image: nginx
     replicas: 3
     selector:
       matchLabels:
        type: front-end

• Once the file is ready, create the deployment using deployment defination file

  $ kubectl create -f deployment-defination.yaml
  

• To see the created deployment

  $ kubectl get deployment
  

• The deployment automatically creates a ReplicaSet. To see the replicasets

  $ kubeclt get replicaset
  

• The replicasets ultimately creates PODs. To see the PODs

  $ kubectl get pods
  

  

• To see the all objects at once

  $ kubectl get all
  

  

K8s Reference Docs:

• https://kubernetes.io/docs/concepts/workloads/controllers/deployment/
• https://kubernetes.io/docs/tutorials/kubernetes-basics/deploy-app/deploy-intro/
• https://kubernetes.io/docs/concepts/cluster-administration/manage-deployment/
• https://kubernetes.io/docs/concepts/overview/working-with-objects/kubernetes-objects/