gitlab-ci-runner-marathon

A customized Docker image for running scalable GitLab CI runners on DC/OS or vanilla Mesos via Marathon.

Configuration

The GitLab runner can be configured by environment variables. For a complete overview, have a look at the docs/gitlab_runner_register_arguments.md file.

The most important ones are:

• GITLAB_SERVICE_NAME: The Mesos DNS service name, e.g. gitlab.marathon.mesos. This strongly depends on your setup, i.e. how you launched GitLab and how you configured Mesos DNS. (mandatory)
• REGISTRATION_TOKEN: The registration token tu use with the GitLab instance. See the docs for details. (mandatory)
• RUNNER_EXECUTOR: The type of the executor to use, e.g. shell or docker. See the executor docs for more details. (mandatory)
• RUNNER_CONCURRENT_BUILDS: The number of concurrent builds this runner should be able to handel. Default is 1.
• RUNNER_TAG_LIST: If you want to use tags in you .gitlab-ci.yml, then you need to specify the comma-separated list of tags. This is useful to distinguish the runner types.

Run on DC/OS (or vanilla Mesos)

This project currently comes in two flavors, split in branches:

• master: The master branch is not using Docker-in-Docker techniques for the CI runners
• dind: The dind branch provides a Docker-in-Docker solution for the CI runners

See jpetazzo's article for the pros and cons regarding Docker-in-Docker.

When not using DinD, mounting the docker.socket and the docker binary in the GitLab CI runner container from the host is necessary. It's possible that you have to mount other files as well, depending on your environment. See below for an example.

In the following examples, we assume that you're running the GitLab Universe package as service gitlab on DC/OS internal Marathon instance, which is also available to the runners via the external_url of the GitLab configuration. This normally means that GitLab is exposed on a public agent node via marathon-lb.

Have a look below for a GitLab CE sample configuration.

Shell runner

An example for a shell runner on DC/OS 1.8, where you need to map the Docker binary and socket, as well as other libs to the GitLab runner container. This enables the build of Docker images.

{
  "id": "gitlab-runner-shell",
  "container": {
    "type": "DOCKER",
    "docker": {
      "image": "Azulinho/gitlab-ci-runner-marathon:latest",
      "network": "HOST",
      "forcePullImage": true
    },
    "volumes": [
      {
        "containerPath": "/var/run/docker.sock",
        "hostPath": "/var/run/docker.sock",
        "mode": "RW"
      }
    ]
  },
  "instances": 1,
  "cpus": 1,
  "mem": 2048,
  "env": {
    "GITLAB_SERVICE_NAME": "gitlab.marathon.mesos",
    "REGISTRATION_TOKEN": "zzNWmRE--SBfeMfiKCMh",
    "RUNNER_EXECUTOR": "shell",
    "RUNNER_TAG_LIST": "shell,build-as-docker",
    "RUNNER_CONCURRENT_BUILDS": "4"
  }
}

Docker runner

Here's an example for a Docker runner, which enables builds inside Docker containers:

{
  "id": "gitlab-runner-docker",
  "container": {
    "type": "DOCKER",
    "docker": {
      "image": "Azulinho/gitlab-ci-runner-marathon:latest",
      "network": "HOST",
      "forcePullImage": true
    },
    "volumes": [
      {
        "containerPath": "/var/run/docker.sock",
        "hostPath": "/var/run/docker.sock",
        "mode": "RW"
      }
    ]
  },
  "instances": 1,
  "cpus": 1,
  "mem": 2048,
  "env": {
    "GITLAB_SERVICE_NAME": "gitlab.marathon.mesos",
    "REGISTRATION_TOKEN": "zzNWmRE--SBfeMfiKCMh",
    "RUNNER_EXECUTOR": "docker",
    "RUNNER_TAG_LIST": "docker,build-in-docker",
    "RUNNER_CONCURRENT_BUILDS": "4",
    "DOCKER_IMAGE": "node:6-wheezy"
  }
}

Make sure you choose a useful default Docker image via DOCKER_IMAGE, for example if you want to build Node.js projects, the node:6-wheezy image. This can be overwritten with the image property in the .gitlab-ci.yml file (see the GitLab CI docs.

Usage in GitLab CI

Builds as Docker

An .gitlab-ci.yml example of using the build-as-docker tag to trigger a build on the runner(s) with shell executors:

stages:
  - ci

build-job:
  stage: ci
  tags:
    - build-as-docker
  script:
    - docker build -t Azulinho/test .

This assumes your project has a Dockerfile, for example

FROM nginx

Builds in Docker

An .gitlab-ci.yml example of using the build-in-docker tag to trigger a build on the runner(s) with Docker executors:

image: node:6-wheezy

stages:
  - ci

test-job:
  stage: ci
  tags:
    - build-in-docker
  script:
    - node --version