Working with gitlab-ci-localΒΆ

The ns-3 project repository is currently hosted in GitLab, which includes continuos integration (CI) tools to automate build, tests, packaging and distribution of software. The CI works based on jobs, that are defined on YAML files.

The ns-3 GitLab CI files are located in ns-3-dev/utils/tests/. The main GitLab CI file is gitlab-ci.yml. The different jobs are used to check if a multitude of compilers and package versions are compatible with the current ns-3 build, which is why a build is usually followed by a test run. Other CI jobs build and warn about missing the documentation.

The GitLab CI jobs are executed based on pipelines containing a sequence of job batches. Jobs within a batch can be executed in parallel. These pipelines can be triggered manually, or scheduled to run automatically per commit and/or based on a time period (ns-3 has daily and weekly pipelines scheduled).

The GitLab CI free tier is very slow, taking a lot of time to identify issues during active merge request development.

Note: the free tier now requires a credit card due to crypto miners abuse.

GitLab-CI-local is a tool that allows an user to use the GitLab CI configuration files locally, allowing for the debugging of CI settings and pipelines without requiring pushes to test repositories or main repositories that fill up the CI job queues with failed jobs due to script errors.

GitLab-CI-local relies on Docker to setup the environment to execute the jobs.

Note: Docker is usually setup in root mode, requiring frequent use of administrative permissions/sudo. However, this is highly discouraged. You can configure Docker to run in rootless mode. From this point onwards, we assume Docker is configured in rootless mode.

After installing both Docker in rootless mode and GitLab-CI-local, the ns-3 jobs can be listed using the following command:

~/ns-3-dev$ gitlab-ci-local --file ./utils/tests/gitlab-ci.yml --list
parsing and downloads finished in 226 ms
name                                   description  stage          when        allow_failure  needs
weekly-build-ubuntu-18.04-debug                     build          on_success  false


weekly-build-clang-11-optimized                     build          on_success  false
cppyy-22.04                                         build          on_success  false
per-commit-compile-debug                            build          on_success  false
per-commit-compile-release                          build          on_success  false
per-commit-compile-optimized                        build          on_success  false
daily-test-debug                                    test           on_success  false
daily-test-release                                  test           on_success  false
daily-test-optimized                                test           on_success  false
daily-test-optimized-valgrind                       test           on_success  false
weekly-test-debug-valgrind                          test           on_success  false
weekly-test-release-valgrind                        test           on_success  false
weekly-test-optimized-valgrind                      test           on_success  false
weekly-test-takes-forever-optimized                 test           on_success  false
doxygen                                             documentation  on_success  false
manual                                              documentation  on_success  false
tutorial                                            documentation  on_success  false
models                                              documentation  on_success  false

To execute the per-commit-compile-release job, or any of the others listed above, use the following command.

~/ns-3-dev$ gitlab-ci-local --file ./utils/tests/gitlab-ci.yml per-commit-compile-release

WARNING: if you do not specify the job name, all jobs that can be executed in parallel will be executed at the same time. You may run out of disk, memory or both.

Some jobs might require a previous job to complete successfully before getting started. The doxygen job is one of these.

~/ns-3-dev$ gitlab-ci-local --file ./utils/tests/gitlab-ci.yml doxygen
Using fallback git
Using fallback git
parsing and downloads finished in 202 ms
doxygen                               starting archlinux:latest (documentation)
doxygen                               pulled archlinux:latest in 64 ms
doxygen                               > still running...
doxygen                               > still running...
doxygen                               copied to container in 20 s
doxygen                               imported cache 'ccache-' in 3.67 s
~/ns-3-dev/.gitlab-ci-local/artifacts/pybindgen doesn't exist, did you forget --needs

As instructed by the previous command output, you can add the --needs to build required jobs before proceeding. However, doing so will run all jobs as the doxygen is only supposed to run after weekly jobs are successfully executed.

Another option is to run the specific job that produces the required artifact. In this case the pybindgen job.

Note: Pybindgen has been replaced by Cppyy, which does not produce artifacts to be consumed by other jobs. However, the example is kept for reference.

~/ns-3-dev$ gitlab-ci-local --file ./utils/tests/gitlab-ci.yml pybindgen
Using fallback git
Using fallback git
parsing and downloads finished in 202 ms
pybindgen                               starting archlinux:latest (build)


pybindgen                             $ git diff src > pybindgen_new.patch
pybindgen                             exported artifacts in 911 ms
pybindgen                             copied artifacts to cwd in 56 ms
pybindgen                             finished in 5.77 min

 PASS  pybindgen

Then run the doxygen job again:

~/ns-3-dev$ gitlab-ci-local --file ./utils/tests/gitlab-ci.yml doxygen
Using fallback git
Using fallback git
parsing and downloads finished in 170 ms
doxygen                               starting archlinux:latest (documentation)


doxygen                               >      1 files with warnings
doxygen                               > Doxygen Warnings Summary
doxygen                               > ----------------------------------------
doxygen                               >      1 directories
doxygen                               >      1 files
doxygen                               >     23 warnings
doxygen                               > done.
doxygen                               exported cache ns-3-ccache-storage/ 'ccache-' in 6.86 s
doxygen                               exported artifacts in 954 ms
doxygen                               copied artifacts to cwd in 59 ms
doxygen                               finished in 15 min

 PASS  doxygen

Artifacts built by the CI jobs will be stored in separate subfolders based on the job name.