Preparing a build environment
- Fetch upstream assets
Building the package
- Building an EE package
Miscellaneous
- Cleaning files created during build
- Getting further help on Omnibus

Building an `omnibus-gitlab` package locally

Preparing a build environment

Docker images with necessary build tools for building omnibus-gitlab packages can be found at the GitLab Omnibus Builder project’s Container Registry.

Install Docker.

Containers need access to 4GB of memory to complete builds. Consult the documentation for your container runtime. Docker for Mac and Docker for Windows are known to set this value to 2GB for default installations.
Pull the Docker image for the OS you need to build a package for. The current version of the image used officially by omnibus-gitlab is referred to the BUILDER_IMAGE_REVISION environment variable in the CI configuration
```
docker pull registry.gitlab.com/gitlab-org/gitlab-omnibus-builder/debian_10:${BUILDER_IMAGE_REVISION}
```

Clone the Omnibus GitLab source and change to the cloned directory:

git clone https://gitlab.com/gitlab-org/omnibus-gitlab.git ~/omnibus-gitlab
cd ~/omnibus-gitlab

Start the container and enter its shell, while mounting the omnibus-gitlab directory in it:

docker run -v ~/omnibus-gitlab:~/omnibus-gitlab -it registry.gitlab.com/gitlab-org/gitlab-omnibus-builder/debian_10:${BUILDER_IMAGE_REVISION} bash

By default, omnibus-gitlab will choose internal GitLab repositories from dev.gitlab.org to fetch sources of various GitLab components. Since this repository is not publicly accessible, set the environment variable ALTERNATIVE_SOURCES to true.
```
export ALTERNATIVE_SOURCES=true
```
Details of sources of various components is available in the .custom_sources.yml file.
By default, omnibus-gitlab codebase is optimized to be used in a CI environment. One such optimization is reusing the pre-compiled Rails assets that is built by the GitLab CI pipeline. To know how to leverage this in your builds, check Fetch upstream assets section. Or, you can choose to compile the assets during the package build by setting the COMPILE_ASSETS environment variable.
```
export COMPILE_ASSETS=true
```

Install the libraries and other dependencies:

cd ~/omnibus-gitlab
bundle install
bundle binstubs --all

Fetch upstream assets

Pipelines on GitLab and GitLab-FOSS projects will create a Docker image with pre-compiled assets and publish it to the container registry. While building packages, it’s possible to reuse these images instead of compiling the assets again, and thus save time:

Fetch the assets Docker image corresponding to the ref of GitLab or GitLab-FOSS you are building. For example, to pull the asset image corresponding to latest master ref, run the following:
```
docker pull registry.gitlab.com/gitlab-org/gitlab/gitlab-assets-ee:master
```

Create a container using that image

docker create --name gitlab_asset_cache registry.gitlab.com/gitlab-org/gitlab/gitlab-assets-ee:master

Copy the asset directory from the container to the host

docker cp gitlab_asset_cache:/assets ~/gitlab-assets

While starting the build environment container, mount the asset directory in it:

docker run -v ~/omnibus-gitlab:~/omnibus-gitlab -v ~/gitlab-assets:/gitlab-assets -it registry.gitlab.com/gitlab-org/gitlab-omnibus-builder/debian_10:${BUILDER_IMAGE_REVISION} bash

Instead of setting COMPILE_ASSETS to true, set the path where assets can be found:
```
export ASSET_PATH=/gitlab-assets
```

Building the package

Once you have prepared the build environment and have made necessary changes, if any, you can build packages using the provided Rake tasks:

For builds to work, Git working directory should be clean. So, commit your changes to a new branch.
Run the Rake task to build the package:
```
 bundle exec rake build:project
```

The packages will be built and available in the ~/omnibus-gitlab/pkg directory.

Building an EE package

By default, omnibus-gitlab will build a CE package. If you want to build an EE package, set the ee environment variable before running the Rake task:

export ee=true

Miscellaneous

Cleaning files created during build

You can clean up all temporary files generated during the build process with omnibus’s clean command:

bin/omnibus clean

Adding the --purge purge option removes ALL files generated during the build including the project install directory (/opt/gitlab) and the package cache directory (/var/cache/omnibus/pkg):

bin/omnibus clean --purge

Getting further help on Omnibus

Full help for the Omnibus command line interface can be accessed with the help command:

bin/omnibus help

Building an omnibus-gitlab package locally