gitlab-ci: add multiple stages/tiers for tests

We have many test configurations (i.e. distros like fedora:37,
debian:9).  Almost all of them run manually triggered, because running
them every time would be wasteful.

Still, even as we trigger those tests only seldom, whenever we trigger
them all together, they consume still too many resources of the
freedesktop.org gitlab infrastructure.

One possibility would be to just drop old distros (e.g. fedora:30).
Which tests are setup in gitlab-ci is constantly refined and adjusted.
So dropping some distros is not necessarily wrong and bound to happen
eventually.

However, I also don't find it great to just disable tests that are still
passing. If we want to avoid consuming too many resources, we can just
choose not to run those tests. We don't need to enforce that by deleting
tests. Once deleted, such a configuration cannot be tested anymore as it
would be too cumbersome to recreate the setup manually.

Instead, introduce stages/tiers to clearer mark configuration that we
should test even less frequently.

Note that it is still required from the developer to not trigger too
many tests at once, to not monopolize the CI resources. The stages
should make that clearer to see, but don't solve it. Deleting tests
might solve it, but only if we delete a significant number of those
tests, which seems not desirable.

.gitlab-ci/ci.template

@@ -17,17 +17,37 @@
 
 .templates_sha: &template_sha ffe4d1b10aab7534489f0c4bbc4c5899df17d3f2 # see https://docs.gitlab.com/ee/ci/yaml/#includefile
 
+{# Group distros by their common (name,base_type,tag) tuples.#}
+{% set distro_groups = [] %}
+{% for distro in distributions %}
+  {% set g = {'name':distro.name,'base_type':distro.base_type,'tag':distro.tag} %}
+  {% if g not in distro_groups %}
+  {%   do distro_groups.append(g) %}
+  {% endif %}
+{% endfor %}
+
+{# The "default_distro" builds our pages and is used for check-{tree,patch} tests. It is the first distro with tier 1. #}
+{% set default_distro = [] %}
+{% for distro in distributions %}
+  {% if distro.tier == 1 and default_distro|length == 0 %}
+    {% do default_distro.append(distro) %}
+  {% endif %}
+{% endfor %}
+{% set default_distro = default_distro[0] %}
+
 include:
-{% for distro in distributions|sort(attribute="name") %}
-  # {{ distro.name.capitalize() }} container builder template
+{% for distro_group in distro_groups|sort(attribute='name') %}
+  # {{ distro_group.name.capitalize() }} container builder template
   - project: 'freedesktop/ci-templates'
     ref: *template_sha
-    file: '/templates/{{distro.name}}.yml'
+    file: '/templates/{{distro_group.name}}.yml'
 {% endfor %}
 
 stages:
   - prep
-  - test
+  - tier1
+  - tier2
+  - tier3
   - deploy
   - triage
   - container_clean
@@ -41,17 +61,17 @@ variables:
   #
   # This is done by running `ci-fairy generate-template` and possibly bumping
   # ".default_tag".
-{% for distro in distributions %}
-  {{"%-13s"| format(distro.name.upper() + '_TAG:')}}'{{distro.tag}}-{{
+{% for distro_group in distro_groups|sort(attribute='name') %}
+  {{"%-13s"| format(distro_group.name.upper() + '_TAG:')}}'{{distro_group.tag}}-{{
     (ci_fairy.hashfiles('./.gitlab-ci/config.yml',
                         './.gitlab-ci/ci.template',
-                        './.gitlab-ci/' + distro.base_type + '-install.sh',
-                        './contrib/' + distro.base_type + '/REQUIRED_PACKAGES'))[0:12]
+                        './.gitlab-ci/' + distro_group.base_type + '-install.sh',
+                        './contrib/' + distro_group.base_type + '/REQUIRED_PACKAGES'))[0:12]
   }}'
 {% endfor %}
 
-{% for distro in distributions %}
-  {{"%-13s"| format(distro.name.upper() + '_EXEC:')}}'bash .gitlab-ci/{{distro.base_type}}-install.sh'
+{% for distro_group in distro_groups|sort(attribute='name') %}
+  {{"%-13s"| format(distro_group.name.upper() + '_EXEC:')}}'bash .gitlab-ci/{{distro_group.base_type}}-install.sh'
 {% endfor %}
 
 .nm_artifacts:
@@ -93,6 +113,9 @@ variables:
     FDO_DISTRIBUTION_VERSION: '{{version}}'
     FDO_DISTRIBUTION_TAG: ${{distro.name.upper()}}_TAG
     FDO_DISTRIBUTION_EXEC: ${{distro.name.upper()}}_EXEC
+{% if distro.tier > 1 %}
+  when: manual
+{% endif %}
 {% endfor %}
 {% endfor %}
 
@@ -151,7 +174,6 @@ variables:
 #################################################################
 
 .build@template:
-  stage: test
   script:
     - env
     - r=0
@@ -174,12 +196,12 @@ t_{{distro.name}}:{{version}}:
   extends:
     - .build@template
     - .fdo.distribution-image@{{distro.name}}
-{% if distro.name == pages_build.name and
-      version == pages_build.version %}
+{% if distro == default_distro %}
     - .nm_artifacts
 {% else %}
     - .nm_artifacts_debug
 {% endif %}
+  stage: tier{{distro.tier}}
   variables:
     FDO_DISTRIBUTION_VERSION: '{{version}}'
     FDO_DISTRIBUTION_TAG: ${{distro.name.upper()}}_TAG
@@ -191,7 +213,7 @@ t_{{distro.name}}:{{version}}:
     {% endif %}
   needs:
     - "{{distro.name}}:{{version}}@container-prep"
-{% if not version in distro.get('always', []) and (distro.name != pages_build.name or version != pages_build.version) %}
+{% if distro.tier > 1 %}
   when: manual
 {% endif %}
 {% endfor %}
@@ -205,26 +227,26 @@ t_{{distro.name}}:{{version}}:
 
 check-patch:
   extends:
-    - .fdo.distribution-image@{{pages_build.name}}
+    - .fdo.distribution-image@{{default_distro.name}}
   variables:
-    FDO_DISTRIBUTION_VERSION: '{{pages_build.version}}'
-    FDO_DISTRIBUTION_TAG: ${{pages_build.name.upper()}}_TAG
+    FDO_DISTRIBUTION_VERSION: '{{default_distro.versions[0]}}'
+    FDO_DISTRIBUTION_TAG: ${{default_distro.name.upper()}}_TAG
   needs:
-    - "{{pages_build.name}}:{{pages_build.version}}@container-prep"
-  stage: test
+    - "{{default_distro.name}}:{{default_distro.versions[0]}}@container-prep"
+  stage: tier1
   script:
     - date '+%Y%m%d-%H%M%S'; NM_CHECKPATCH_FETCH_UPSTREAM=1 contrib/scripts/checkpatch-feature-branch.sh
   allow_failure: true
 
 check-tree:
   extends:
-    - .fdo.distribution-image@{{pages_build.name}}
+    - .fdo.distribution-image@{{default_distro.name}}
   variables:
-    FDO_DISTRIBUTION_VERSION: '{{pages_build.version}}'
-    FDO_DISTRIBUTION_TAG: ${{pages_build.name.upper()}}_TAG
+    FDO_DISTRIBUTION_VERSION: '{{default_distro.versions[0]}}'
+    FDO_DISTRIBUTION_TAG: ${{default_distro.name.upper()}}_TAG
   needs:
-    - "{{pages_build.name}}:{{pages_build.version}}@container-prep"
-  stage: test
+    - "{{default_distro.name}}:{{default_distro.versions[0]}}@container-prep"
+  stage: tier1
   script:
     - date '+%Y%m%d-%H%M%S'; contrib/scripts/nm-python-black-format.sh --check
     - date '+%Y%m%d-%H%M%S'; git ls-files -z -- 'po/*.po' | xargs -0 -n1 msgfmt -vc
@@ -242,9 +264,9 @@ pages:
   only:
     - main
   dependencies:
-    - t_{{pages_build.name}}:{{pages_build.version}}
+    - t_{{default_distro.name}}:{{default_distro.versions[0]}}
   needs:
-    - t_{{pages_build.name}}:{{pages_build.version}}
+    - t_{{default_distro.name}}:{{default_distro.versions[0]}}
 
 triage:issues:
   stage: triage

.gitlab-ci/config.yml

@@ -8,7 +8,7 @@
 #
 
 # We're happy to rebuild all containers when one changes.
-.default_tag: &default_tag '2023-01-18.0'
+.default_tag: &default_tag '2023-04-11.0'
 
 
 # The list of all distributions we want to create job for.
@@ -17,6 +17,21 @@ distributions:
   - name: fedora
     tag: *default_tag
     base_type: fedora
+    # Tier1 is used to build the pages and check-{tree,patch}
+    tier: 1
+    versions:
+      - '37'
+  - name: fedora
+    tag: *default_tag
+    base_type: fedora
+    tier: 2
+    versions:
+      - '36'
+      - '38'
+  - name: fedora
+    tag: *default_tag
+    base_type: fedora
+    tier: 3
     versions:
       - '30'
       - '31'
@@ -24,12 +39,10 @@ distributions:
       - '33'
       - '34'
       - '35'
-      - '36'
-      - '37'
-      - '38'
   - name: ubuntu
     tag: *default_tag
     base_type: debian
+    tier: 2
     versions:
       - '18.04'
       - '20.04'
@@ -39,31 +52,39 @@ distributions:
   - name: debian
     tag: *default_tag
     base_type: debian
+    tier: 2
     versions:
-      - '9'
       - '10'
       - '11'
-      - 'testing'
       - 'sid'
+  - name: debian
+    tag: *default_tag
+    base_type: debian
+    tier: 3
+    versions:
+      - '9'
+      - 'testing'
   - name: centos
     tag: *default_tag
     base_type: fedora
+    tier: 2
     versions:
       - '7.5.1804'
+      - '7.9.2009'
+      - '8.1.1911'
+      - '8.3.2011'
+  - name: centos
+    tag: *default_tag
+    base_type: fedora
+    tier: 3
+    versions:
       - '7.6.1810'
       - '7.7.1908'
       - '7.8.2003'
-      - '7.9.2009'
-      - '8.1.1911'
       - '8.2.2004'
-      - '8.3.2011'
   - name: alpine
     tag: *default_tag
     base_type: alpine
+    tier: 2
     versions:
       - 'latest'
-
-# specifies which of the above distros is used as source for pages
-pages_build:
-  name: fedora
-  version: '37'