buildspec.backend.yml

version: 0.2

# ─────────────────────────────────────────────────────────────
# Backend Lambda CI/CD – Canary Deployment Buildspec
# ─────────────────────────────────────────────────────────────
# 1. Detects which lambda folders changed (git diff)
# 2. Builds the shared layer if layer changed
# 3. Packages only the changed lambdas
# 4. Publishes new versions + writes CodeDeploy appspec files
# 5. Triggers CodeDeploy canary deployments per changed lambda
# ─────────────────────────────────────────────────────────────

env:
  variables:
    LAYER_NAME: "lambda_layer"
    CODEDEPLOY_APP: ""
    # Mapping: function_name:folder_name:zip_name
    LAMBDA_MAP: "admin_blog_posts:admin_blog_post:blog_posts presign_lambda:presign_lambda:presign_lambda public_posts_lambda:public_posts_lambda:public_posts_lambda leads_lambda:leads_lambda:leads_lambda notifications_lambda:notifications_lambda:notifications_lambda cleanup_lambda:cleanup_lambda:cleanup_lambda"

phases:
  install:
    runtime-versions:
      nodejs: 20

  pre_build:
    commands:
      # ── Ensure enough git history for diff ──
      - |
        if git rev-parse HEAD~1 >/dev/null 2>&1; then
          echo "Git history available"
        else
          echo "Shallow clone detected — fetching more history"
          git fetch --deepen=2 2>/dev/null || true
        fi
      # ── Detect which folders changed ──
      - echo "── Change Detection ──"
      - |
        # Get changed files between current and previous commit
        CHANGED_FILES=$(git diff --name-only HEAD~1 HEAD 2>/dev/null || echo "FULL_DEPLOY")
        echo "Changed files:"
        echo "$CHANGED_FILES"

        # Check if the shared layer changed
        LAYER_CHANGED="false"
        if [ "$CHANGED_FILES" = "FULL_DEPLOY" ] || echo "$CHANGED_FILES" | grep -q "^backend/blog_lambda_layer/"; then
          LAYER_CHANGED="true"
          echo "Layer changed or first run — all lambdas will be redeployed"
        fi

        # Determine which lambda folders changed
        CHANGED_LAMBDAS=""
        for ENTRY in $LAMBDA_MAP; do
          FUNC_NAME=$(echo "$ENTRY" | cut -d: -f1)
          FOLDER=$(echo "$ENTRY" | cut -d: -f2)

          if [ "$CHANGED_FILES" = "FULL_DEPLOY" ] || [ "$LAYER_CHANGED" = "true" ] || echo "$CHANGED_FILES" | grep -q "^backend/${FOLDER}/"; then
            CHANGED_LAMBDAS="$CHANGED_LAMBDAS $ENTRY"
            echo "→ Will deploy: $FUNC_NAME (folder: $FOLDER)"
          fi
        done

        if [ -z "$CHANGED_LAMBDAS" ]; then
          echo "No lambda changes detected — skipping deployment"
          echo "SKIP_BUILD=true" > /tmp/build_env.sh
        else
          echo "SKIP_BUILD=false" > /tmp/build_env.sh
          echo "LAYER_CHANGED=$LAYER_CHANGED" >> /tmp/build_env.sh
          echo "CHANGED_LAMBDAS=\"$CHANGED_LAMBDAS\"" >> /tmp/build_env.sh
        fi
      - cat /tmp/build_env.sh
      - . /tmp/build_env.sh

  build:
    commands:
      - . /tmp/build_env.sh
      - |
        if [ "$SKIP_BUILD" = "true" ]; then
          echo "Nothing to deploy — exiting cleanly"
          mkdir -p /tmp/deploy_artifacts
          echo '{"status":"skipped","reason":"no backend changes detected"}' > /tmp/deploy_artifacts/build_result.json
          exit 0
        fi
      # ── Build layer if changed ──
      - |
        if [ "$LAYER_CHANGED" = "true" ]; then
          echo "── Building Lambda Layer ──"
          cd "$CODEBUILD_SRC_DIR/backend/blog_lambda_layer"
          rm -rf nodejs/node_modules
          cd nodejs && npm ci --omit=dev && cd ..
          zip -rq layer.zip nodejs/

          LAYER_VERSION_ARN=$(aws lambda publish-layer-version \
            --layer-name "$LAYER_NAME" \
            --compatible-runtimes nodejs18.x \
            --zip-file "fileb://layer.zip" \
            --query 'LayerVersionArn' \
            --output text)
          echo "Published layer: $LAYER_VERSION_ARN"
        else
          echo "── Layer unchanged — fetching current layer ARN ──"
          LAYER_VERSION_ARN=$(aws lambda get-function --function-name "admin_blog_posts" \
            --query 'Configuration.Layers[0].Arn' --output text)
          echo "Current layer: $LAYER_VERSION_ARN"
        fi
        echo "LAYER_VERSION_ARN=$LAYER_VERSION_ARN" >> /tmp/build_env.sh

      # ── Package, deploy, and trigger canary for each changed lambda ──
      - . /tmp/build_env.sh
      - mkdir -p /tmp/deploy_artifacts
      - |
        for ENTRY in $CHANGED_LAMBDAS; do
          FUNC_NAME=$(echo "$ENTRY" | cut -d: -f1)
          FOLDER=$(echo "$ENTRY" | cut -d: -f2)
          ZIP_NAME=$(echo "$ENTRY" | cut -d: -f3)

          echo ""
          echo "══════════════════════════════════════════"
          echo "  Deploying: $FUNC_NAME"
          echo "══════════════════════════════════════════"

          # Package
          cd "$CODEBUILD_SRC_DIR/backend/$FOLDER"
          zip -rq "/tmp/${FUNC_NAME}.zip" index.js
          echo "  ✓ Packaged"

          # Get current live alias version (before update)
          CURRENT_VERSION=$(aws lambda get-alias \
            --function-name "$FUNC_NAME" \
            --name "live" \
            --query 'FunctionVersion' \
            --output text)
          echo "  Current live version: $CURRENT_VERSION"

          # Update function code
          aws lambda update-function-code \
            --function-name "$FUNC_NAME" \
            --zip-file "fileb:///tmp/${FUNC_NAME}.zip" \
            --no-cli-pager > /dev/null
          aws lambda wait function-updated --function-name "$FUNC_NAME"
          echo "  ✓ Code updated"

          # Update layer if it changed
          if [ "$LAYER_CHANGED" = "true" ]; then
            aws lambda update-function-configuration \
              --function-name "$FUNC_NAME" \
              --layers "$LAYER_VERSION_ARN" \
              --no-cli-pager > /dev/null
            aws lambda wait function-updated --function-name "$FUNC_NAME"
            echo "  ✓ Layer updated"
          fi

          # Publish new version
          NEW_VERSION=$(aws lambda publish-version \
            --function-name "$FUNC_NAME" \
            --query 'Version' \
            --output text)
          echo "  ✓ Published version: $NEW_VERSION"

          # Write AppSpec for CodeDeploy canary deployment
          FUNC_ARN=$(aws lambda get-function \
            --function-name "$FUNC_NAME" \
            --query 'Configuration.FunctionArn' \
            --output text)

          cat > "/tmp/deploy_artifacts/appspec_${FUNC_NAME}.yml" <<EOF
        version: 0.0
        Resources:
          - ${FUNC_NAME}:
              Type: AWS::Lambda::Function
              Properties:
                Name: "${FUNC_NAME}"
                Alias: "live"
                CurrentVersion: "${CURRENT_VERSION}"
                TargetVersion: "${NEW_VERSION}"
        EOF

          echo "  ✓ AppSpec written"

          # Trigger CodeDeploy deployment
          DEPLOYMENT_GROUP="${FUNC_NAME}-canary"
          APPSPEC_CONTENT=$(cat "/tmp/deploy_artifacts/appspec_${FUNC_NAME}.yml")

          DEPLOYMENT_ID=$(aws deploy create-deployment \
            --application-name "$CODEDEPLOY_APP" \
            --deployment-group-name "$DEPLOYMENT_GROUP" \
            --revision "revisionType=AppSpecContent,appSpecContent={content='$(echo "$APPSPEC_CONTENT" | sed "s/'/\\\\'/g")'}" \
            --query 'deploymentId' \
            --output text 2>&1) || true

          if [ -n "$DEPLOYMENT_ID" ] && [ "$DEPLOYMENT_ID" != "None" ]; then
            echo "  ✓ CodeDeploy triggered: $DEPLOYMENT_ID"
            echo "$FUNC_NAME=$DEPLOYMENT_ID" >> /tmp/deploy_artifacts/deployments.txt
          else
            echo "  ⚠ CodeDeploy trigger failed — falling back to direct alias update"
            aws lambda update-alias \
              --function-name "$FUNC_NAME" \
              --name "live" \
              --function-version "$NEW_VERSION" \
              --no-cli-pager > /dev/null
            echo "  ✓ Alias updated directly to v$NEW_VERSION"
          fi
        done

  post_build:
    commands:
      - . /tmp/build_env.sh
      - |
        if [ "$SKIP_BUILD" = "true" ]; then
          echo "── No changes — build skipped ──"
          exit 0
        fi
      - echo ""
      - echo "── Deployment Summary ──"
      - |
        if [ -f /tmp/deploy_artifacts/deployments.txt ]; then
          echo "CodeDeploy canary deployments in progress:"
          cat /tmp/deploy_artifacts/deployments.txt
          echo ""
          echo "Monitor in the AWS CodeDeploy console."
          echo "Traffic will shift: 10% → wait 5 min → 100%"
          echo "Auto-rollback on CloudWatch alarm trigger."
        else
          echo "All deployments completed via direct alias updates."
        fi

artifacts:
  base-directory: /tmp/deploy_artifacts
  files:
    - "**/*"
  discard-paths: false