If you’re using GitLab then you have a free container registry for your projects. Do you want to repeat the process of building and publishing a docker image every day when you have GitLab built-in CI/CD too? The answer definitely is “no”, so let’s get started :)
Your .gitlab-ci.yml
We need to use Docker-in-Docker to reach our approaches, and your .gitlab-ci.yml might look like this:
stages:
- build
build:
stage: build
image: docker:19.03.11
variables:
DOCKER_TLS_CERTDIR: "/certs"
DOCKER_IMAGE: <my-docker-image>
services:
- docker:19.03.11-dind
before_script:
- docker login -u <username> -p <deploy_token> $CI_REGISTRY
script:
- docker build -t $DOCKER_IMAGE .
- docker push $IMAGE
only:
- master
You can get <username> and <deploy_token> by create a GitLab Deploy Token follow this tutorial.
NOTE: If you too lazy for create GitLab environment variables to secure your CI file for this command:
docker login -u <username> -p <deploy_token> $CI_REGISTRY
You can create a user named with gitlab-deploy-token then the username and token of the Deploy Token will be automatically exposed to the CI/CD jobs as environment variables. And you can replace the command above with this command:
docker login -u $CI_DEPLOY_USER -p $CI_DEPLOY_PASSWORD $CI_REGISTRY
Conclusion
Now we have our simple CI file that helps us automate boring repeat processes. And you can customize or improve it base on your needs.