Continuous Deployment to Google Kubernetes Engine with CircleCI (config.yaml)

circleci-config.yml

version: 2

jobs:
  build_and_test:
    # ... insert your test suite here

  docker_push:
    # Build app container and push it to the GCR registry
    # Note: we want to build and push an image with tags based on both
    # the Git commit hash AND the branch name. This way, we can refer to
    # images by commit (which is immutable) or branch name (which
    # dynamically tracks the latest build for each branch).
    docker:
      - image: bayesimpact/circleci
    working_directory: ~/repo
    steps:
      - checkout
      - setup_remote_docker
      - run:
          name: Authenticate with GCR
          command: |
            echo "${GCR_DOCKER_REGISTRY_PASSWORD}" | docker login -u _json_key --password-stdin https://gcr.io
      - run:
          name: Build app image
          command: |
            docker build --rm=false \
            -t gcr.io/${GCR_PROJECT}/myapp:${CIRCLE_SHA1} \
            -t gcr.io/${GCR_PROJECT}/myapp:${CIRCLE_BRANCH} \
            -f ./Dockerfile .
      - run:
          name: Push app image
          command: |
            docker push gcr.io/${GCR_PROJECT}/myapp:${CIRCLE_SHA1}
            docker push gcr.io/${GCR_PROJECT}/myapp:${CIRCLE_BRANCH}

  kubernetes_deploy:
    # Update the existing Kubernetes deployment to point to the new image
    docker:
      - image: google/cloud-sdk:alpine
    working_directory: ~/repo
    steps:
      - run:
          name: Deploy the current commit on this branch to the GKE cluster
          command: |
            gcloud components install kubectl
            echo "${GKE_CD_SERVICE_ACCOUNT_KEY}" > .key.json
            gcloud auth activate-service-account --key-file .key.json
            gcloud config set compute/zone "${GKE_ZONE}"
            gcloud config set project "${GKE_PROJECT}"
            gcloud container clusters get-credentials "${GKE_CLUSTER}" --zone "${GKE_ZONE}"

            if [ "${CIRCLE_BRANCH}" == "prod" ]; then
                DEPLOYMENT_PREFIX="production"
            elif [ "${CIRCLE_BRANCH}" == "staging" ]; then
                DEPLOYMENT_PREFIX="staging"
            else
                echo "unknown branch ${CIRCLE_BRANCH}"
                exit 1
            fi

            kubectl set image deployment/${DEPLOYMENT_PREFIX}-app ${DEPLOYMENT_PREFIX}-app=gcr.io/${GCR_PROJECT}/myapp:${CIRCLE_SHA1}

workflows:
  version: 2
  build_and_test:
    jobs:
      # note: skip tests on prod and staging branches.
      # This assumes your workflow ensures that tests pass in the dev branch
      # before the code is promoted to staging.
      - build_and_test:
          filters:
            branches:
              ignore:
                - prod
                - staging
  deploy:
    jobs:
      # note: this step only runs on prod and staging branches.
      - docker_push:
          filters:
            branches:
              only:
                - prod
                - staging
      - kubernetes_deploy:
          filters:
            branches:
              only:
                - prod
                - staging
          requires:
            - docker_push