ci: reuse build metadata for docker build

Part-of: <https://dev.funkwhale.audio/funkwhale/funkwhale/-/merge_requests/2482>

.gitlab-ci.yml

@@ -298,10 +298,15 @@ build_metadata:
   variables:
     GIT_FETCH_EXTRA_FLAGS: --prune
   script:
-    - scripts/build_metadata.py --format env | tee build_metadata.env
+    - make build-metadata
+    - make docker-metadata
   artifacts:
     reports:
       dotenv: build_metadata.env
+    paths:
+      - docker-bake.json
+      - docker-bake.api.json
+      - docker-bake.front.json
 
 build_api_schema:
   stage: build
@@ -436,6 +441,8 @@ docker:
   tags: [docker, privileged, multiarch]
   stage: build
   needs:
+    - job: build_metadata
+      artifacts: true
     - job: test_api
       optional: true
     - job: test_front
@@ -488,9 +495,6 @@ docker:
     - make docker-build BUILD_ARGS="--metadata-file metadata.json $BUILD_ARGS"
     - cat metadata.json
   artifacts:
-    name: docker_build_files_${CI_COMMIT_REF_NAME}
+    name: docker_metadata_${CI_COMMIT_REF_NAME}
     paths:
-      - docker-bake.json
-      - docker-bake.api.json
-      - docker-bake.front.json
       - metadata.json

Makefile

@@ -9,6 +9,11 @@ BAKE_FILES = \
 docker-bake.%.json:
 	./scripts/build_metadata.py --format bake --bake-target $* --bake-image docker.io/funkwhale/$* > $@
 
-docker-build: $(BAKE_FILES)
+docker-metadata: $(BAKE_FILES)
+
+docker-build: docker-metadata
 	docker buildx bake $(foreach FILE,$(BAKE_FILES), --file $(FILE)) --print $(BUILD_ARGS)
 	docker buildx bake $(foreach FILE,$(BAKE_FILES), --file $(FILE)) 		 $(BUILD_ARGS)
+
+build-metadata:
+	./scripts/build_metadata.py --format env | tee build_metadata.env

scripts/build_metadata.py

@@ -76,8 +76,6 @@ def latest_tag_on_branch() -> str:
     """
     Return the latest tag on the current branch.
     """
-    if "CI" in os.environ:
-        sh("git fetch origin --tags")
     return sh("git describe --tags --abbrev=0")