Ensure deployments are only triggered if the manifests exist for that environment

refs: TryGhost/Pro#5

Means that we can have services that either only have a staging or production deployment, good for development and tiny apps which only operate in a single environment

Author: sam-lord

.github/workflows/deploy.yml

@@ -33,47 +33,63 @@ jobs:
       if: startsWith(github.ref, 'refs/tags/')
       run: |
         echo "ENVIRONMENT=production" >> $GITHUB_ENV
+
+    - name: Checkout code
+      uses: actions/checkout@v3
+    
+    - name: Check for folder existence
+      id: checkfolder
+      run: |
+        if [ -d "./k8s/overlays/${{ env.ENVIRONMENT }}" ]; then
+          echo "::set-output name=manifests_exist::true"
+        else
+          echo "::set-output name=manifests_exist::false"
+        fi
     
     - name: Set project id
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       run: |
         if [[ "${{ env.ENVIRONMENT }}" == "production" ]]; then
           echo "PROJECT_ID=${{ env.PRD_PROJECT_ID }}" >> $GITHUB_ENV
         elif [[ "${{ env.ENVIRONMENT }}" == "staging" ]]; then
           echo "PROJECT_ID=${{ env.STG_PROJECT_ID }}" >> $GITHUB_ENV
         fi
 
-    - name: Checkout code
-      uses: actions/checkout@v3
-
     - name: 'Authenticate to Google Cloud'
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       uses: 'google-github-actions/auth@v1'
       with:
         # TODO: Use different secret for production and staging
         credentials_json: ${{ secrets.GCP_SA_JSON }}
 
     - name: Set up Google Cloud SDK
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       uses: google-github-actions/[email protected]
       with:
         project_id: ${{ env.PROJECT_ID }}
 
     - name: Authenticate with GKE
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       uses: 'google-github-actions/get-gke-credentials@v1'
       with:
         cluster_name: 'ghost-pro'
         location: 'europe-west4-a'
 
     - name: Build final manifest
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       run: |
         kubectl kustomize ./k8s/overlays/${{ env.ENVIRONMENT }} > /tmp/built-manifest.yaml
     
     - name: Setup yq
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       uses: supplypike/setup-bin@v3
       with:
         uri: 'https://github.com/mikefarah/yq/releases/download/v4.35.1/yq_linux_amd64'
         name: 'yq'
         version: '4.35.1'
 
     - name: Extract Deployment Name and Namespace
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       run: |
         deployment_name=$(yq e 'select(.kind == "Deployment") | .metadata.name' /tmp/built-manifest.yaml)
         namespace=$(yq e 'select(.kind == "Deployment") | .metadata.namespace' /tmp/built-manifest.yaml | sed 's/^null$/default/')
@@ -84,6 +100,7 @@ jobs:
         echo "NAMESPACE=$namespace" >> $GITHUB_ENV
     
     - name: Apply the manifests to the Kubernetes cluster
+      if: steps.checkfolder.outputs.manifests_exist == 'true'
       run: |
         kubectl apply -k k8s/overlays/${{ env.ENVIRONMENT }}
         kubectl rollout restart deployment ${{ env.DEPLOYMENT_NAME }} --namespace ${{ env.NAMESPACE }}