Contribute to GitLab Runner development

1. Install dependencies and Go runtime

Add $GOBIN to your $PATH to ensure binaries installed via go install are runnable. Your shell looks for binaries in $PATH directories sequentially, so choose an order based on your preference:

export PATH="$(go env GOBIN):$PATH"


export PATH="$PATH:$(go env GOBIN)"

For Debian/Ubuntu

sudo apt-get install -y mercurial git-core wget make build-essential
sudo tar -C /usr/local -xzf go*-*.tar.gz

For CentOS

sudo yum install mercurial wget make
sudo yum groupinstall 'Development Tools'
sudo tar -C /usr/local -xzf go*-*.tar.gz

For macOS

Using binary package:

sudo tar -C /usr/local -xzf go*-*.tar.gz

Using installation package:

open go*-*.pkg

For FreeBSD

pkg install go-1.18.6 gmake git mercurial

2. Install Docker Engine

The Docker Engine is required to create pre-built image that is embedded into GitLab Runner and loaded when using Docker executor.

To install Docker, follow the Docker installation instructions for your OS.

Make sure you have a binfmt_misc on the machine that is running your Docker Engine. This is required for building ARM images that are embedded into the GitLab Runner binary.

  • For Debian/Ubuntu it’s sufficient to execute:

    sudo apt-get install binfmt-support qemu-user-static
  • For Docker for MacOS/Windows binfmt_misc is enabled by default.

  • For CoreOS (but also works on Debian and Ubuntu) you need to execute the following script on system start:

    set -xe
    /sbin/modprobe binfmt_misc
    mount -t binfmt_misc binfmt_misc /proc/sys/fs/binfmt_misc
    # Support for ARM binaries through Qemu:
    { echo ':arm:M::\x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-arm-static:' > /proc/sys/fs/binfmt_misc/register; } 2>/dev/null
    { echo ':armeb:M::\x7fELF\x01\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff:/usr/bin/qemu-armeb-static:' > /proc/sys/fs/binfmt_misc/register; } 2>/dev/null
    { echo ':aarch64:M::\x7fELF\x02\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\xb7\x00:\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff:/usr/bin/qemu-aarch64-static:CF' > /proc/sys/fs/binfmt_misc/register; } 2>/dev/null

3. Download GitLab Runner sources

go get

4. Install GitLab Runner dependencies

After you clone GitLab Runner, cd into the gitlab-runner directory and download and restore all build dependencies:

git clone <gitlab-runner-uri>
cd gitlab-runner
make deps

For FreeBSD use gmake deps

5. Run GitLab Runner

Normally you would use gitlab-runner. In order to compile and run the Go sources, use the Go toolchain:

make runner-and-helper-bin-host
./out/binaries/gitlab-runner run

You can run GitLab Runner in debug-mode:

make runner-and-helper-bin-host
./out/binaries/gitlab-runner --debug run

make runner-and-helper-bin-host is a superset of make runner-bin-host which in addition takes care of building the Runner Helper Docker archive dependencies.

Building the Docker images

If you want to build the Docker images, run make runner-and-helper-docker-host, which will:

  1. Build gitlab-runner-helper and create a helper Docker image from it.
  2. Compile GitLab Runner for linux/amd64.
  3. Build a DEB package for Runner. The official GitLab Runner images are based on Alpine and Ubuntu, and the Ubuntu image build uses the DEB package.
  4. Build the Alpine and Ubuntu versions of the gitlab/gitlab-runner image.

6. Run test suite locally

GitLab Runner test suite consists of “core” tests and tests for executors. Tests for executors require certain binaries to be installed on your local machine. Some of these binaries cannot be installed on all operating systems. If a binary is not installed tests requiring this binary will be skipped.

These are the binaries that you can install:

  1. VirtualBox and Vagrant; the Vagrant Parallels plugin is also required
  2. kubectl with minikube
  3. Parallels Pro or Business edition
  4. PowerShell

After installing the binaries run:

make development_setup

To execute the tests run:

make test

7. Run tests with helper image version of choice

If you are developing functionality inside a helper, you’ll most likely want to run tests with the version of the Docker image that contains the newest changes.

If you run tests without passing -ldflags, the default version in version.go is development. This means that the runner defaults to pulling a helper image with the latest tag.

Make targets

make targets inject -ldflags automatically. You can run all tests by using:

make simple-test

make targets also inject -ldflags for parallel_test_execute, which is most commonly used by the CI/CD jobs.

Custom go test arguments

In case you want a more customized go test command, you can use print_ldflags as make target:

go test -ldflags "$(make print_ldflags)" -run TestDockerCommandBuildCancel -v ./executors/docker/...

In GoLand

Currently, GoLand doesn’t support dynamic Go tool arguments, so you’ll need to run make print_ldflags first and then paste it in the configuration.

To use the debugger, make sure to remove the last two flags (-s -w).

Helper image

Build the newest version of the helper image with:

make helper-dockerarchive-host

Then you’ll have the image ready for use:

REPOSITORY                                                    TAG                      IMAGE ID            CREATED             SIZE
gitlab/gitlab-runner-helper                                   x86_64-a6bc0800          f10d9b5bbb41        32 seconds ago      57.2MB

Helper image with Kubernetes

If you are running a local Kubernetes cluster make sure to reuse the cluster’s Docker daemon to build images. For example, with minikube:

eval $(minikube docker-env)

8. Install optional tools

  • Install golangci-lint, used for the make lint target.
  • Install markdown-lint and vale, used for the make lint-docs target.

Installation instructions will pop up when running a Makefile target if a tool is missing.

9. Contribute

You can start hacking gitlab-runner code. If you need an IDE to edit and debug code, there are a few free suggestions you can use:

Managing build dependencies

GitLab Runner uses Go Modules to manage its dependencies.

Don’t add dependency from upstream default branch when version tags are available.


The Runner codebase makes a distinction between unit and integration tests in the following way:

  • Unit test files have a suffix of _test.go and contain the following build directive in the header:

      // go:build !integration
  • Integration test files have a suffix of _integration_test.go and contain the following build directive in the header:

      // go:build integration

    They can be run by adding -tags=integration to the go test command.

To test the state of the build directives in test files, make check_test_directives can be used.

Developing for Windows on a non-windows environment

We provide a Vagrantfile to help you run a Windows Server 2019 or Windows 10 instance, since we are using multiple machines inside of Vagrant.

The following are required:

  • Vagrant installed.
  • Virtualbox installed.
  • Around 30GB of free hard disk space on your computer.

Which virtual machine to use depends on your use case:

  • The Windows Server machine has Docker pre-installed and should always be used when you are developing on GitLab Runner for Windows.
  • The Windows 10 machine is there for you to have a windows environment with a GUI which sometimes can help you debugging some Windows features. Note that you cannot have Docker running inside of Windows 10 because nested virtualization is not supported.

Running vagrant up windows_10 will start the Windows 10 machine for you. To:

  • SSH inside of the Windows 10 machine, run vagrant ssh windows_10.
  • Access the GUI for the Windows 10, you can connect via RDP by running vagrant rdp windows_10, which will connect to the machine using a locally installed RDP program.

For both machines, the GitLab Runner source code is synced bi-directionally so that you can edit from your machine with your favorite editor. The source code can be found under the $GOROOT environment variable. We have a RUNNER_SRC environment variable which you can use to find out the full path so when using PowerShell, you can use cd $Env:RUNNER_SRC.

Other resources

  1. Reviewing GitLab Runner merge requests
  2. Add support for new Windows Version
  3. Runner Group - Team Resources