# This workflow performs a "blue-green" deployment, while preserving the original deployment object
# and name. It accomplishes this by temporarily redirecting traffic to a *clone* of the original
# deployment, then after upgrading the original deployment to a later version, transfering traffic
# back to the original (now upgraded) deployment.
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: k8s-bluegreen-
spec:
  entrypoint: k8s-bluegreen
  arguments:
    parameters:
    - name: deployment-name
    - name: service-name
    - name: new-deployment-manifest
    - name: new-service-manifest
 
  templates:
  - name: k8s-bluegreen
    steps:
    # 1. Create a parallel Kubernetes deployment with tweaks to name and selectors
    - - name: create-blue-deployment
        template: clone-deployment

    # 2. Wait for parallel deployment to become ready
    - - name: wait-for-blue-deployment
        template: wait-deployment-ready
        arguments:
          parameters:
          - name: deployment-name
            value: '{{workflow.parameters.deployment-name}}-blue'

    # 3. Patch the named service to point to the parallel deployment app
    - - name: switch-service-to-blue-deployment
        template: patch-service

    # 4. Update the original deployment (receiving no traffic) with a new version
    - - name: apply-green-deployment
        template: apply-manifest
        arguments:
          parameters:
          - name: manifest
            value: '{{workflow.parameters.new-deployment-manifest}}'

    # 5. Wait for the original deployment, now updated, to become ready
    - - name: wait-for-green-deployment
        template: wait-deployment-ready
        arguments:
          parameters:
          - name: deployment-name
            value: '{{workflow.parameters.deployment-name}}'

    # dummy approval step for demo purposes. Sleeps for 30 seconds
    - - name: approve
        template: approve

    # 6. Patch the named service to point to the original, now updated app
    - - name: switch-service-to-green-deployment
        template: apply-manifest
        arguments:
          parameters:
          - name: manifest
            value: '{{workflow.parameters.new-service-manifest}}'

    # 7. Remove the cloned deployment (no longer receiving traffic)
    - - name: delete-cloned-deployment
        template: delete-deployment

# end of steps

  # clone deployment creates a "blue" clone of an existing deployment.
  # -blue is appended to the metadata.name, as well as the values in the spec.selector.matchLabels,
  # and spec.template.metadata.labels
  - name: clone-deployment
    container:
      image: argoproj/argoexec:v2.1.1
      command: [sh, -c, -x]
      args:
      - kubectl get --export -o json deployment.apps/{{workflow.parameters.deployment-name}} > /tmp/original-deploy &&
        jq -r '.metadata.name+="-blue" |
               .spec.template.metadata.labels += (.spec.template.metadata.labels | to_entries | map(select(.key != "applications.argoproj.io/app-name")) | map(.value+="-blue") | from_entries) |
               .spec.selector.matchLabels += (.spec.selector.matchLabels | to_entries | map(select(.key != "applications.argoproj.io/app-name")) | map(.value+="-blue") | from_entries)'
            /tmp/original-deploy > /tmp/cloned-deploy &&
        cat  /tmp/cloned-deploy &&
        kubectl apply -o yaml -f /tmp/cloned-deploy

  - name: apply-manifest
    inputs:
      parameters:
      - name: manifest
    resource:
      action: apply
      manifest: '{{inputs.parameters.manifest}}'

  - name: wait-deployment-ready
    inputs:
      parameters:
      - name: deployment-name
    container:
      image: argoproj/argoexec:v2.1.1
      command: [kubectl, rollout, status, --watch=true, 'deployments/{{inputs.parameters.deployment-name}}']

  - name: patch-service
    container:
      image: argoproj/argoexec:v2.1.1
      command: [sh, -c, -x]
      args:
      - kubectl get -n default service {{workflow.parameters.service-name}} --export -o json > /tmp/original-svc &&
        jq '.spec.selector = (.spec.selector | with_entries(.value+="-blue"))' /tmp/original-svc > /tmp/blue-svc &&
        kubectl apply -o yaml -f /tmp/blue-svc

  - name: delete-deployment
    resource:
      action: delete
      manifest: |
        apiVersion: apps/v1
        kind: Deployment
        metadata:
          name: {{workflow.parameters.deployment-name}}-blue

  - name: approve
    container:
      image: argoproj/argoexec:v2.1.1
      command: [sleep, "30"]