Bitbucket Pipelines: Build Docker Image + GCR Image Push + GKE Deploy

bitbucket-pipelines.yml

image: openjdk:11-jdk-slim

definitions:
    caches:
        gradlewrapper: ~/.gradle/wrapper
    gke-kubectl-pipe: &pipe atlassian/google-gke-kubectl-run:1.3.1
    gke-kubectl-pipe-variables: &pipe-variables
        KEY_FILE: $GKE_API_KEYFILE
        PROJECT: $GCP_PROJECT_ID
        COMPUTE_ZONE: $GKE_COMPUTE_ZONE
        CLUSTER_NAME: $GKE_CLUSTER_NAME
        KUBECTL_COMMAND: "set image deployment/$K8S_DEPLOYMENT_NAME $K8S_CONTAINER_NAME=$IMAGE_NAME --namespace=$K8S_NAMESPACE"        
    steps:
        - step: &lint
            name: Lint
            caches:
                - gradle
                - gradlewrapper
            script:
                - ./gradlew lintKotlin

        - step: &test
            name: Test
            caches:
                - gradle
                - gradlewrapper
            script:
                - ./gradlew test

        - step: &assemble
            name: Assemble
            caches:
                - gradle
                - gradlewrapper
            script:
                - ./gradlew assemble
            artifacts:
                - build/libs/*.jar

        - step: &build-image
            name: Build Docker image
            services:
                - docker
            caches:
                - docker
            script:
                - export IMAGE_NAME=$GCP_IMAGE_NAME
                - docker build -t $IMAGE_NAME --build-arg JAR_FILE=build/libs/app.jar .
                - docker save --output docker.tar $IMAGE_NAME
            artifacts:
                - docker.tar

        - step: &push-image-to-gcr
            name: Push image
            image: google/cloud-sdk:alpine
            services:
                - docker
            caches:
                - docker
            script:
                # backup docker image
                - docker load --input docker.tar

                # Authenticating with the service account key file
                - echo $GCP_API_KEYFILE | base64 -d > ./gcloud-api-key.json
                - gcloud info --run-diagnostics
                - gcloud auth activate-service-account --key-file gcloud-api-key.json
                - gcloud config set project $GCP_PROJECT_ID

                # Login to google docker hub
                - cat ./gcloud-api-key.json | docker login -u _json_key --password-stdin https://$GCP_REGISTRY_HOSTNAME

                # Prepare image name and shorten commit id
                - export IMAGE_NAME=$GCP_REGISTRY_HOSTNAME/$GCP_PROJECT_ID/$GCP_IMAGE_NAME
                - export BITBUCKET_COMMIT_SHORT="${BITBUCKET_COMMIT::7}"

                # If any image does not exist with commit id, then
                - if [ "$(gcloud container images list-tags ${IMAGE_NAME} | grep ${BITBUCKET_COMMIT_SHORT})" == '' ]; then

                # Tag docker image with commit id and push
                - docker tag $GCP_IMAGE_NAME $IMAGE_NAME:$BITBUCKET_COMMIT_SHORT
                - docker push $IMAGE_NAME:$BITBUCKET_COMMIT_SHORT

                # Tag docker image with :latest tag and push
                - docker tag $GCP_IMAGE_NAME ${IMAGE_NAME}
                - docker push ${IMAGE_NAME}

                # Tag docker image with commit tag and push (if pipeline triggered with tag)
                - if [ "${BITBUCKET_TAG}" != '' ]; then
                - docker tag $GCP_IMAGE_NAME $IMAGE_NAME:$BITBUCKET_TAG
                - docker push $IMAGE_NAME:$BITBUCKET_TAG
                - fi

                # Else image exists with commit id
                - else

                # Add commit tag into existing image with commit id (if pipeline triggered with tag)
                - if [ "${BITBUCKET_TAG}" != '' ]; then
                - gcloud container images add-tag $IMAGE_NAME:$BITBUCKET_COMMIT_SHORT $IMAGE_NAME:$BITBUCKET_TAG --quiet
                - fi

                # End if
                - fi

        - step: &deploy-to-gke-staging
            name: Deploy to Staging
            deployment: staging
            script:
                - export BITBUCKET_COMMIT_SHORT="${BITBUCKET_COMMIT::7}"
                - export IMAGE_NAME=$GCP_REGISTRY_HOSTNAME/$GCP_PROJECT_ID/$GCP_IMAGE_NAME:$BITBUCKET_COMMIT_SHORT
                - pipe: *pipe
                  variables: *pipe-variables

        - step: &deploy-to-gke-production
            name: Deploy to Production
            deployment: production
            # Added for manual promotion
            trigger: manual
            script:
                - export IMAGE_NAME=$GCP_REGISTRY_HOSTNAME/$GCP_PROJECT_ID/$GCP_IMAGE_NAME:$BITBUCKET_TAG
                - pipe: *pipe
                  variables: *pipe-variables

pipelines:
    pull-requests:
        '**':
            - parallel:
                - step: *lint
                - step: *test
    tags:
        '*':
            - parallel:
                - step: *lint
                - step: *test
            - step: *assemble
            - step: *build-image
            - step: *push-image-to-gcr
            - step: *deploy-to-gke-staging
            - step: *deploy-to-gke-production
    branches:
        master:
            - parallel:
                - step: *lint
                - step: *test
            - step: *assemble
            - step: *build-image
            - step: *push-image-to-gcr
            - step: *deploy-to-gke-staging