gitlab: centralize the container tag name

We use a fixed container tag of 'latest' so that contributors' forks
don't end up with an ever growing number of containers as they work
on throwaway feature branches.

This fixed tag causes problems running CI upstream in stable staging
branches, however, because the stable staging branch will publish old
container content that clashes with that needed by primary staging
branch. This makes it impossible to reliably run CI pipelines in
parallel in upstream for different staging branches.

This introduces $QEMU_CI_CONTAINER_TAG global variable as a way to
change which tag container publishing uses. Initially it can be set
by contributors as a git push option if they want to override the
default use of 'latest' eg

  git push gitlab <branch> -o ci.variable=QEMU_CONTAINER_TAG=fish

this is useful if contributors need to run pipelines for different
branches concurrently in their forks.

Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230608164018.2520330-2-berrange@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

.gitlab-ci.d/base.yml

@@ -1,4 +1,10 @@
 
+variables:
+  # On stable branches this needs changing. Should also be
+  # overridden per pipeline if running pipelines concurrently
+  # for different branches in contributor forks.
+  QEMU_CI_CONTAINER_TAG: latest
+
 # The order of rules defined here is critically important.
 # They are evaluated in order and first match wins.
 #

.gitlab-ci.d/buildtest-template.yml

@@ -1,7 +1,7 @@
 .native_build_job_template:
   extends: .base_job_template
   stage: build
-  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:latest
+  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:$QEMU_CI_CONTAINER_TAG
   before_script:
     - JOBS=$(expr $(nproc) + 1)
   script:
@@ -40,7 +40,7 @@
 .common_test_job_template:
   extends: .base_job_template
   stage: test
-  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:latest
+  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:$QEMU_CI_CONTAINER_TAG
   script:
     - scripts/git-submodule.sh update roms/SLOF
     - meson subprojects download $(cd build/subprojects && echo *)

.gitlab-ci.d/buildtest.yml

@@ -532,7 +532,7 @@ build-without-defaults:
 build-libvhost-user:
   extends: .base_job_template
   stage: build
-  image: $CI_REGISTRY_IMAGE/qemu/fedora:latest
+  image: $CI_REGISTRY_IMAGE/qemu/fedora:$QEMU_CI_CONTAINER_TAG
   needs:
     job: amd64-fedora-container
   script:
@@ -572,7 +572,7 @@ build-tools-and-docs-debian:
 # of what topic branch they're currently using
 pages:
   extends: .base_job_template
-  image: $CI_REGISTRY_IMAGE/qemu/debian-amd64:latest
+  image: $CI_REGISTRY_IMAGE/qemu/debian-amd64:$QEMU_CI_CONTAINER_TAG
   stage: test
   needs:
     - job: build-tools-and-docs-debian

.gitlab-ci.d/container-template.yml

@@ -5,7 +5,8 @@
   services:
     - docker:dind
   before_script:
-    - export TAG="$CI_REGISTRY_IMAGE/qemu/$NAME:latest"
+    - export TAG="$CI_REGISTRY_IMAGE/qemu/$NAME:$QEMU_CI_CONTAINER_TAG"
+    # Always ':latest' because we always use upstream as a common cache source
     - export COMMON_TAG="$CI_REGISTRY/qemu-project/qemu/qemu/$NAME:latest"
     - docker login $CI_REGISTRY -u "$CI_REGISTRY_USER" -p "$CI_REGISTRY_PASSWORD"
     - until docker info; do sleep 1; done

.gitlab-ci.d/crossbuild-template.yml

@@ -1,7 +1,7 @@
 .cross_system_build_job:
   extends: .base_job_template
   stage: build
-  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:latest
+  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:$QEMU_CI_CONTAINER_TAG
   timeout: 80m
   script:
     - mkdir build
@@ -27,7 +27,7 @@
 .cross_accel_build_job:
   extends: .base_job_template
   stage: build
-  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:latest
+  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:$QEMU_CI_CONTAINER_TAG
   timeout: 30m
   script:
     - mkdir build
@@ -39,7 +39,7 @@
 .cross_user_build_job:
   extends: .base_job_template
   stage: build
-  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:latest
+  image: $CI_REGISTRY_IMAGE/qemu/$IMAGE:$QEMU_CI_CONTAINER_TAG
   script:
     - mkdir build
     - cd build

.gitlab-ci.d/static_checks.yml

@@ -26,7 +26,7 @@ check-dco:
 check-python-minreqs:
   extends: .base_job_template
   stage: test
-  image: $CI_REGISTRY_IMAGE/qemu/python:latest
+  image: $CI_REGISTRY_IMAGE/qemu/python:$QEMU_CI_CONTAINER_TAG
   script:
     - make -C python check-minreqs
   variables:
@@ -37,7 +37,7 @@ check-python-minreqs:
 check-python-tox:
   extends: .base_job_template
   stage: test
-  image: $CI_REGISTRY_IMAGE/qemu/python:latest
+  image: $CI_REGISTRY_IMAGE/qemu/python:$QEMU_CI_CONTAINER_TAG
   script:
     - make -C python check-tox
   variables:

docs/devel/ci-jobs.rst.inc

@@ -70,6 +70,11 @@ in a handful of namespaces
    repository CI settings, or as git push variables, to influence
    which jobs get run in a pipeline
 
+ * QEMU_CI_CONTAINER_TAG - the tag used to publish containers
+   in stage 1, for use by build jobs in stage 2. Defaults to
+   'latest', but if running pipelines for different branches
+   concurrently, it should be overridden per pipeline.
+
  * nnn - other misc variables not falling into the above
    categories, or using different names for historical reasons
    and not yet converted.