[PATCH v5 1/4] Jobs based on custom runners: documentation and configuration placeholder

[Cleber Rosa <crosa@redhat.com>]

As described in the included documentation, the "custom runner" jobs
extend the GitLab CI jobs already in place.  One of their primary
goals of catching and preventing regressions on a wider number of host
systems than the ones provided by GitLab's shared runners.

This sets the stage in which other community members can add their own
machine configuration documentation/scripts, and accompanying job
definitions.  As a general rule, those newly added contributed jobs
should run as "non-gating", until their reliability is verified (AKA
"allow_failure: true").

Signed-off-by: Cleber Rosa <crosa@redhat.com>
---
 .gitlab-ci.d/custom-runners.yml | 14 ++++++++++++++
 .gitlab-ci.yml                  |  1 +
 docs/devel/ci.rst               | 28 ++++++++++++++++++++++++++++
 docs/devel/index.rst            |  1 +
 4 files changed, 44 insertions(+)
 create mode 100644 .gitlab-ci.d/custom-runners.yml
 create mode 100644 docs/devel/ci.rst

diff --git a/.gitlab-ci.d/custom-runners.yml b/.gitlab-ci.d/custom-runners.yml
new file mode 100644
index 0000000000..3004da2bda
--- /dev/null
+++ b/.gitlab-ci.d/custom-runners.yml
@@ -0,0 +1,14 @@
+# The CI jobs defined here require GitLab runners installed and
+# registered on machines that match their operating system names,
+# versions and architectures.  This is in contrast to the other CI
+# jobs that are intended to run on GitLab's "shared" runners.
+
+# Different than the default approach on "shared" runners, based on
+# containers, the custom runners have no such *requirement*, as those
+# jobs should be capable of running on operating systems with no
+# compatible container implementation, or no support from
+# gitlab-runner.  To avoid problems that gitlab-runner can cause while
+# reusing the GIT repository, let's enable the recursive submodule
+# strategy.
+variables:
+  GIT_SUBMODULE_STRATEGY: recursive
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 8b6d495288..ae19442e93 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -12,6 +12,7 @@ include:
   - local: '/.gitlab-ci.d/opensbi.yml'
   - local: '/.gitlab-ci.d/containers.yml'
   - local: '/.gitlab-ci.d/crossbuilds.yml'
+  - local: '/.gitlab-ci.d/custom-runners.yml'
 
 .native_build_job_template: &native_build_job_definition
   stage: build
diff --git a/docs/devel/ci.rst b/docs/devel/ci.rst
new file mode 100644
index 0000000000..585b7bf4b8
--- /dev/null
+++ b/docs/devel/ci.rst
@@ -0,0 +1,28 @@
+==
+CI
+==
+
+QEMU has configurations enabled for a number of different CI services.
+The most up to date information about them and their status can be
+found at::
+
+   https://wiki.qemu.org/Testing/CI
+
+Jobs on Custom Runners
+======================
+
+Besides the jobs run under the various CI systems listed before, there
+are a number additional jobs that will run before an actual merge.
+These use the same GitLab CI's service/framework already used for all
+other GitLab based CI jobs, but rely on additional systems, not the
+ones provided by GitLab as "shared runners".
+
+The architecture of GitLab's CI service allows different machines to
+be set up with GitLab's "agent", called gitlab-runner, which will take
+care of running jobs created by events such as a push to a branch.
+Here, the combination of a machine, properly configured with GitLab's
+gitlab-runner, is called a "custom runner".
+
+The GitLab CI jobs definition for the custom runners are located under::
+
+  .gitlab-ci.d/custom-runners.yml
diff --git a/docs/devel/index.rst b/docs/devel/index.rst
index 22854e334d..b178448a91 100644
--- a/docs/devel/index.rst
+++ b/docs/devel/index.rst
@@ -23,6 +23,7 @@ Contents:
    migration
    atomics
    stable-process
+   ci
    qtest
    decodetree
    secure-coding-practices
-- 
2.25.4