Jobs based on custom runners: docs and gitlab-runner setup playbook

To have the jobs dispatched to custom runners, gitlab-runner must
be installed, active as a service and properly configured.  The
variables file and playbook introduced here should help with those
steps.

The playbook introduced here covers the Linux distributions and
has been primarily tested on OS/machines that the QEMU project
has available to act as runners, namely:

 * Ubuntu 20.04 on aarch64
 * Ubuntu 18.04 on s390x

But, it should work on all other Linux distributions.  Earlier
versions were tested on FreeBSD too, so chances of success are
high.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Willian Rampazzo <willianr@redhat.com>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Willian Rampazzo <willianr@redhat.com>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210630012619.115262-4-crosa@redhat.com>
Message-Id: <20210709143005.1554-4-alex.bennee@linaro.org>

1 files changed, 55 insertions, 0 deletions

diff --git a/docs/devel/ci.rst b/docs/devel/ci.rst
index bfedbb1025..b3bf3ef615 100644
--- a/docs/devel/ci.rst
+++ b/docs/devel/ci.rst
@@ -70,3 +70,58 @@ privileges, such as those from the ``root`` account or those obtained
 by ``sudo``.  If necessary, please refer to ``ansible-playbook``
 options such as ``--become``, ``--become-method``, ``--become-user``
 and ``--ask-become-pass``.
+
+gitlab-runner setup and registration
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The gitlab-runner agent needs to be installed on each machine that
+will run jobs.  The association between a machine and a GitLab project
+happens with a registration token.  To find the registration token for
+your repository/project, navigate on GitLab's web UI to:
+
+ * Settings (the gears-like icon at the bottom of the left hand side
+   vertical toolbar), then
+ * CI/CD, then
+ * Runners, and click on the "Expand" button, then
+ * Under "Set up a specific Runner manually", look for the value under
+   "And this registration token:"
+
+Copy the ``scripts/ci/setup/vars.yml.template`` file to
+``scripts/ci/setup/vars.yml``.  Then, set the
+``gitlab_runner_registration_token`` variable to the value obtained
+earlier.
+
+To run the playbook, execute::
+
+  cd scripts/ci/setup
+  ansible-playbook -i inventory gitlab-runner.yml
+
+Following the registration, it's necessary to configure the runner tags,
+and optionally other configurations on the GitLab UI.  Navigate to:
+
+ * Settings (the gears like icon), then
+ * CI/CD, then
+ * Runners, and click on the "Expand" button, then
+ * "Runners activated for this project", then
+ * Click on the "Edit" icon (next to the "Lock" Icon)
+
+Tags are very important as they are used to route specific jobs to
+specific types of runners, so it's a good idea to double check that
+the automatically created tags are consistent with the OS and
+architecture.  For instance, an Ubuntu 20.04 aarch64 system should
+have tags set as::
+
+  ubuntu_20.04,aarch64
+
+Because the job definition at ``.gitlab-ci.d/custom-runners.yml``
+would contain::
+
+  ubuntu-20.04-aarch64-all:
+   tags:
+   - ubuntu_20.04
+   - aarch64
+
+It's also recommended to:
+
+ * increase the "Maximum job timeout" to something like ``2h``
+ * give it a better Description