I recently got into CI/CD, and a good starting point for me was GitLab, since they provide an easy interface for that and i got started about what pipelines and stages are, but i have run into some kind of contradictory thought about GitLab CI running on Docker.
My app runs on Docker Compose. It contains (blah blah) that makes it easy to build & run containers. Each service in the Docker Compose creates a single Docker container, excepting the php-fpm one, which is able to do the thing called "horizontal scale", so I can scale it later.
I will use that Docker Compose for production, I am currently using it in development and I want to use it too in CI/CD pipelines.
However the.gitlab-ci.yml provides support for only one image, so I have to build it and push it to either their GitLab Registry or Docker Hub in order to pull it later in the CI/CD process.
How can I build my Docker Compose's service as a single image in order to push it to the Registry/Docker so I can pull it in the CI/CD?
My project contains a docker folder and a docker-compose.yml. In the docker folder, each service has its own separate directory (php-fpm, nginx, mysql, etc.) and each one (prepare yourself) contains a Dockerfile with build details, especially the php-fpm one (deps and libs are strong with this one)
Each service in the docker-compose.yml has a build context in each of their own folder.
If I was unclear, I can provide additonal info.
I think you search something like this
# .gitlab-ci.yml
image: docker
services:
- docker:dind
build:
script:
- apk add --no-cache py-pip
- pip install docker-compose
- docker-compose up -d
Also good to know:
You don't need dind
to run a docker-compose stack. You can run multiple docker-compose up
commands.
acceptance_testing:
stage: test
before_script:
- docker-compose -p $CI_JOB_ID up -d
script:
- docker-compose -p $CI_JOB_ID exec -T /run/your/test/suite.sh
after_script:
- docker-compose -p $CI_JOB_ID down -v --remove-orphans || true
However the .gitlab-ci.yml provides support for only one image
This is not true. From the official documentation :
Your image will be named after the following scheme:
<registry URL>/<namespace>/<project>/<image>
GitLab supports up to three levels of image repository names. Following examples of image tags are valid:
registry.example.com/group/project:some-tag registry.example.com/group/project/image:latest registry.example.com/group/project/my/image:rc1
So the solution to your problem is simple - just build individual images and push them to GitLab container registry under different image name. The following config should give you an idea:
.template: &build_template
image: docker:stable
services:
- docker:dind
before_script:
- docker login -u $CI_REGISTRY_USER -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
script:
- docker pull $CI_REGISTRY_IMAGE/$IMAGE_NAME:latest || true
- if [ -z ${CI_COMMIT_TAG+x} ];
then docker build
--cache-from $CI_REGISTRY_IMAGE/$IMAGE_NAME:latest
--file $DOCKERFILE_NAME
--tag $CI_REGISTRY_IMAGE/$IMAGE_NAME:$CI_COMMIT_SHA
--tag $CI_REGISTRY_IMAGE/$IMAGE_NAME:$CI_COMMIT_TAG
--tag $CI_REGISTRY_IMAGE/$IMAGE_NAME:latest . ;
else docker build
--cache-from $CI_REGISTRY_IMAGE/$IMAGE_NAME:latest
--file $DOCKERFILE_NAME
--tag $CI_REGISTRY_IMAGE/$IMAGE_NAME:$CI_COMMIT_SHA
--tag $CI_REGISTRY_IMAGE/$IMAGE_NAME:latest . ;
fi
- docker push $CI_REGISTRY_IMAGE/$IMAGE_NAME:$CI_COMMIT_SHA
- if [ -z ${CI_COMMIT_TAG+x} ]; then
docker push $CI_REGISTRY_IMAGE/$IMAGE_NAME:$CI_COMMIT_TAG;
fi
- docker push $CI_REGISTRY_IMAGE/$IMAGE_NAME:latest
build:image1:
<<: *build_template
variables:
IMAGE_NAME: image1
DOCKERFILE_NAME: Dockerfile.1
build:image2:
<<: *build_template
variables:
IMAGE_NAME: image2
DOCKERFILE_NAME: Dockerfile.2
And you should be able to pull the same image using $CI_REGISTRY_IMAGE/$IMAGE_NAME:$CI_COMMIT_SHA
in later pipeline jobs or your compose file (provided that the variables are passed to where you run your compose file).
In my case changing the url causes repository not exists error. So a workaround is to tag different images with different tag. For example I have a project of Drupal which contains two images: one for Drupal source code & second for MySQL database.
I tagged them:
docker build -t registry.mysite.net/drupal/blog:db mysql/db
docker build -t registry.mysite.net/drupal/blog:drupal src/drupal
Here you can see we are not changing the repo url: registry.mysite.net/drupal/blog:drupal
We are only changing the tags. And then to push it to gitlab like:
docker push registry.mysite.net/drupal/blog:db
docker push registry.mysite.net/drupal/blog:drupal
Hope this might help someone.
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