ci: Add a job to trigger a cerbero build, similar to the monorepo

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1513>

.gitlab-ci.yml

@@ -20,6 +20,8 @@ variables:
   # to ensure that we are testing against the same thing as GStreamer itself.
   # The tag name is included above from the main repo.
   GSTREAMER_DOC_IMAGE: "registry.freedesktop.org/gstreamer/gstreamer/amd64/fedora:$FEDORA_TAG-main"
+  # Use the gstreamer image to trigger the cerbero job, same as the monorepo
+  CERBERO_TRIGGER_IMAGE: "registry.freedesktop.org/gstreamer/gstreamer/amd64/fedora:$FEDORA_TAG-main"
   WINDOWS_BASE: "registry.freedesktop.org/gstreamer/gstreamer-rs/windows"
   WINDOWS_RUST_MINIMUM_IMAGE: "$WINDOWS_BASE:$GST_RS_IMG_TAG-main-$GST_RS_MSRV"
   WINDOWS_RUST_STABLE_IMAGE: "$WINDOWS_BASE:$GST_RS_IMG_TAG-main-$GST_RS_STABLE"
@@ -384,3 +386,34 @@ coverage:
       coverage_report:
         coverage_format: cobertura
         path: coverage.xml
+
+cerbero trigger:
+  image: $CERBERO_TRIGGER_IMAGE
+  needs: [ "trigger" ]
+  variables:
+    # We will build this cerbero branch in the cerbero trigger CI
+    CERBERO_UPSTREAM_BRANCH: 'main'
+  script:
+    - ci/cerbero/trigger_cerbero_pipeline.py
+  rules:
+    # Never run post merge
+    - if: '$CI_PROJECT_NAMESPACE == "gstreamer"'
+      when: never
+    # Don't run if the only changes are files that cargo-c does not read
+    - if:
+      changes:
+      - "CHANGELOG.md"
+      - "README.md"
+      - "deny.toml"
+      - "rustfmt.toml"
+      - "typos.toml"
+      - "*.py"
+      - "*.sh"
+      - "Makefile"
+      - "meson.build"
+      - "meson_options.txt"
+      - "**/meson.build"
+      - "ci/*.sh"
+      - "ci/*.py"
+      when: never
+    - when: always

ci/cerbero/trigger_cerbero_pipeline.py

@@ -0,0 +1,103 @@
+#!/usr/bin/python3
+#
+# Copied from gstreamer.git/ci/gitlab/trigger_cerbero_pipeline.py
+
+import time
+import os
+import sys
+import gitlab
+
+CERBERO_PROJECT = 'gstreamer/cerbero'
+
+
+class Status:
+    FAILED = 'failed'
+    MANUAL = 'manual'
+    CANCELED = 'canceled'
+    SUCCESS = 'success'
+    SKIPPED = 'skipped'
+    CREATED = 'created'
+
+    @classmethod
+    def is_finished(cls, state):
+        return state in [
+            cls.FAILED,
+            cls.MANUAL,
+            cls.CANCELED,
+            cls.SUCCESS,
+            cls.SKIPPED,
+        ]
+
+
+def fprint(msg):
+    print(msg, end="")
+    sys.stdout.flush()
+
+
+if __name__ == "__main__":
+    server = os.environ['CI_SERVER_URL']
+    gl = gitlab.Gitlab(server,
+                       private_token=os.environ.get('GITLAB_API_TOKEN'),
+                       job_token=os.environ.get('CI_JOB_TOKEN'))
+
+    def get_matching_user_project(project, branch):
+        cerbero = gl.projects.get(project)
+        # Search for matching branches, return only if the branch name matches
+        # exactly
+        for b in cerbero.branches.list(search=cerbero_branch, iterator=True):
+            if branch == b.name:
+                return cerbero
+        return None
+
+    cerbero = None
+    # We do not want to run on (often out of date) user upstream branch
+    if os.environ["CI_COMMIT_REF_NAME"] != os.environ['CERBERO_UPSTREAM_BRANCH']:
+        try:
+            cerbero_name = f'{os.environ["CI_PROJECT_NAMESPACE"]}/cerbero'
+            cerbero_branch = os.environ["CI_COMMIT_REF_NAME"]
+            cerbero = get_matching_user_project(cerbero_name, cerbero_branch)
+        except gitlab.exceptions.GitlabGetError:
+            pass
+
+    if cerbero is None:
+        cerbero_name = CERBERO_PROJECT
+        cerbero_branch = os.environ["CERBERO_UPSTREAM_BRANCH"]
+        cerbero = gl.projects.get(cerbero_name)
+
+    fprint(f"-> Triggering on branch {cerbero_branch} in {cerbero_name}\n")
+
+    # CI_PROJECT_URL is not necessarily the project where the branch we need to
+    # build resides, for instance merge request pipelines can be run on
+    # 'gstreamer' namespace. Fetch the branch name in the same way, just in
+    # case it breaks in the future.
+    if 'CI_MERGE_REQUEST_SOURCE_PROJECT_URL' in os.environ:
+        project_url = os.environ['CI_MERGE_REQUEST_SOURCE_PROJECT_URL']
+        project_branch = os.environ['CI_MERGE_REQUEST_SOURCE_BRANCH_NAME']
+    else:
+        project_url = os.environ['CI_PROJECT_URL']
+        project_branch = os.environ['CI_COMMIT_REF_NAME']
+
+    variables = {
+        "CI_GST_PLUGINS_RS_URL": project_url,
+        "CI_GST_PLUGINS_RS_REF_NAME": project_branch,
+        # This tells cerbero CI that this is a pipeline started via the
+        # trigger API, which means it can use a deps cache instead of
+        # building from scratch.
+        "CI_GSTREAMER_TRIGGERED": "true",
+    }
+
+    pipe = cerbero.trigger_pipeline(
+        token=os.environ['CI_JOB_TOKEN'],
+        ref=cerbero_branch,
+        variables=variables,
+    )
+
+    fprint(f'Cerbero pipeline running at {pipe.web_url} ')
+    while True:
+        time.sleep(15)
+        pipe.refresh()
+        if Status.is_finished(pipe.status):
+            fprint(f": {pipe.status}\n")
+            sys.exit(0 if pipe.status == Status.SUCCESS else 1)
+        else:
+            fprint(".")