Build and Push images to GCP Container Registry with Gitlab CI

.gitlab-ci.yml

image: docker:latest

# When using dind, it's wise to use the overlayfs driver for
# improved performance.
variables:
  DOCKER_DRIVER: overlay
  GCP_PROJECT_ID: CHANGE-TO-GCP-PROJECT-ID
  IMAGE_NAME: image_id

services:
- docker:dind

stages:
  - publish

publish-image:
  stage: publish
  script:
    # Install CA certs, openssl to https downloads, python for gcloud sdk
    - apk add --update make ca-certificates openssl python
    - update-ca-certificates
    # Write our GCP service account private key into a file
    - echo $GCLOUD_SERVICE_KEY | base64 -d > ${HOME}/gcloud-service-key.json
    # Download and install Google Cloud SDK
    - wget https://dl.google.com/dl/cloudsdk/release/google-cloud-sdk.tar.gz
    - tar zxvf google-cloud-sdk.tar.gz && ./google-cloud-sdk/install.sh --usage-reporting=false --path-update=true
    - google-cloud-sdk/bin/gcloud --quiet components update
    - google-cloud-sdk/bin/gcloud auth activate-service-account --key-file ${HOME}/gcloud-service-key.json
    # Create our image. Expected to create an image 'image_id'
    - make-my-image
    # Tag our image for container registry
    - docker tag $IMAGE_NAME gcr.io/$GCP_PROJECT_ID/$IMAGE_NAME
    # Optionally tag the image with the commit short-sha
    - docker tag $IMAGE_NAME gcr.io/$GCP_PROJECT_ID/$IMAGE_NAME:$(echo $CI_COMMIT_SHA | cut -c1-8)
    - google-cloud-sdk/bin/gcloud docker -- push gcr.io/$GCP_PROJECT_ID/$IMAGE_NAME:latest
    - google-cloud-sdk/bin/gcloud docker -- push gcr.io/$GCP_PROJECT_ID/$IMAGE_NAME:$(echo $CI_COMMIT_SHA | cut -c1-8)
  # Only run builds for these refs
  only:
    - master