Configuration of your builds with .gitlab-ci.yml

From version 7.12, GitLab CI uses a YAML file (.gitlab-ci.yml) for the project configuration. It is placed in the root of your repository and contains definitions of how your project should be built.

The YAML file defines a set of jobs with constraints stating when they should be run. The jobs are defined as top-level elements with a name and always have to contain the script clause:

job1:
  script: "execute-script-for-job1"

job2:
  script: "execute-script-for-job2"

The above example is the simplest possible CI configuration with two separate jobs, where each of the jobs executes a different command. Of course a command can execute code directly (./configure;make;make install) or run a script (test.sh) in the repository.

Jobs are used to create builds, which are then picked up by runners and executed within the environment of the runner. What is important, is that each job is run independently from each other.

.gitlab-ci.yml

The YAML syntax allows for using more complex job specifications than in the above example:

image: ruby:2.1
services:
  - postgres

before_script:
  - bundle_install

stages:
  - build
  - test
  - deploy

job1:
  stage: build
  script:
    - execute-script-for-job1
  only:
    - master
  tags:
    - docker

There are a few keywords that can't be used as job names:

image and services

This allows to specify a custom Docker image and a list of services that can be used for time of the build. The configuration of this feature is covered in separate document: Use Docker.

before_script

before_script is used to define the command that should be run before all builds, including deploy builds. This can be an array or a multiline string.

stages

stages is used to define build stages that can be used by jobs. The specification of stages allows for having flexible multi stage pipelines.

The ordering of elements in stages defines the ordering of builds' execution:

1. Builds of the same stage are run in parallel.
2. Builds of next stage are run after success.

Let's consider the following example, which defines 3 stages:

stages:
  - build
  - test
  - deploy

1. First all jobs of build are executed in parallel.
2. If all jobs of build succeeds, the test jobs are executed in parallel.
3. If all jobs of test succeeds, the deploy jobs are executed in parallel.
4. If all jobs of deploy succeeds, the commit is marked as success.
5. If any of the previous jobs fails, the commit is marked as failed and no jobs of further stage are executed.

There are also two edge cases worth mentioning:

1. If no stages is defined in .gitlab-ci.yml, then by default the build, test and deploy are allowed to be used as job's stage by default.
2. If a job doesn't specify stage, the job is assigned the test stage.

types

Alias for stages.

variables

This feature requires gitlab-runner with version equal or greater than 0.5.0.

GitLab CI allows you to add to .gitlab-ci.yml variables that are set in build environment. The variables are stored in repository and are meant to store non-sensitive project configuration, ie. RAILS_ENV or DATABASE_URL.

variables:
  DATABASE_URL: "postgres://postgres@postgres/my_database"

These variables can be later used in all executed commands and scripts.

The YAML-defined variables are also set to all created service containers, thus allowing to fine tune them.

Jobs

.gitlab-ci.yml allows you to specify an unlimited number of jobs. Each job has to have a unique job_name, which is not one of the keywords mentioned above. A job is defined by a list of parameters that define the build behaviour.

job_name:
  script:
    - rake spec
    - coverage
  stage: test
  only:
    - master
  except:
    - develop
  tags:
    - ruby
    - postgres
  allow_failure: true

script

script is a shell script which is executed by runner. The shell script is prepended with before_script.

job:
  script: "bundle exec rspec"

This parameter can also contain several commands using an array:

job:
  script:
    - uname -a
    - bundle exec rspec

stage

stage allows to group build into different stages. Builds of the same stage are executed in parallel. For more info about the use of stage please check the stages.

only and except

This are two parameters that allow for setting a refs policy to limit when jobs are built:

1. only defines the names of branches and tags for which job will be built.
2. except defines the names of branches and tags for which the job wil not be built.

There are a few rules that apply to usage of refs policy:

1. only and except are exclusive. If both only and except are defined in job specification only only is taken into account.
2. only and except allow for using the regexp expressions.
3. only and except allow for using special keywords: branches and tags. These names can be used for example to exclude all tags and all branches.

job:
  only:
    - /^issue-.*$/ # use regexp
  except:
    - branches # use special keyword

tags

tags is used to select specific runners from the list of all runners that are allowed to run this project.

During registration of a runner, you can specify the runner's tags, ie.: ruby, postgres, development. tags allow you to run builds with runners that have the specified tags assigned:

job:
  tags:
    - ruby
    - postgres

The above specification will make sure that job is built by a runner that have ruby AND postgres tags defined.

Validate the .gitlab-ci.yml

Each instance of GitLab CI has an embedded debug tool called Lint. You can find the link to the Lint in the project's settings page or use short url /lint.

Skipping builds

There is one more way to skip all builds, if your commit message contains tag [ci skip]. In this case, commit will be created but builds will be skipped