# 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, redirects traffic
# back to the original (now upgraded) deployment.
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: k8s-bluegreen-
  annotations:
    argocd.argoproj.io/hook: Sync
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. The string -blue is appended to:
  #  - metadata.name
  #  - spec.selector.matchLabels
  #  - 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}} > /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)'
            /original-deploy > /cloned-deploy &&
        cat  /cloned-deploy &&
        kubectl apply -o yaml -f /cloned-deploy

  # apply-manifest takes a kubernetes manifest and carrys over the app-name label (if present)
  # before running `kubectl apply`. The label is used by ArgoCD for monitoring.
  - name: apply-manifest
    inputs:
      parameters:
      - name: manifest
      artifacts:
      - name: manifest-file
        path: /manifest
        raw:
          data: '{{inputs.parameters.manifest}}'
    container:
      image: argoproj/argoexec:v2.1.1
      command: [sh, -c, -x]
      args:
      - cp /manifest /manifest-new &&
        APP_NAME=$(kubectl get -n default -f /manifest-new -o json | jq -r '.metadata.labels."applications.argoproj.io/app-name"') &&
        if [ "$APP_NAME" != "null" ]; then
          jq -r --arg APP_NAME "$APP_NAME" '.metadata.labels."applications.argoproj.io/app-name" = $APP_NAME' /manifest-new > /manifest-new.tmp &&
          mv /manifest-new.tmp /manifest-new &&
          if [ "$(jq -r .spec.template.metadata.labels /manifest-new)" != "null" ]; then
            jq -r --arg APP_NAME "$APP_NAME" '.spec.template.metadata.labels."applications.argoproj.io/app-name" = $APP_NAME' /manifest-new > /manifest-new.tmp &&
            mv /manifest-new.tmp /manifest-new ;
          fi ;
        fi &&
        cat /manifest-new &&
        kubectl apply -f /manifest-new

  # wait-deployment-ready waits for a deployment to become fully deployed and ready, using the 
  # `kubectl rollout` command
  - 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}}']

  # patch-service updates the service selector labels to point to the "blue" deployment
  - 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 > /original-svc &&
        jq '.spec.selector = (.spec.selector | with_entries(.value+="-blue"))' /original-svc > /blue-svc &&
        kubectl apply -o yaml -f /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"]