[RFC XEN PATCH 1/7] automation: Automatically rebuild debian:unstable container

[Anthony PERARD <anthony.perard@citrix.com>]

Only run this on the staging branch, whenever the dockerfile changes.

Allow to set a suffix when building containers, to be able to test it
before changing the one in production.

Using "rules" instead of "only" as this allow to use variables in the
"changes" rules. Also, "rules" is the preferred keyword as
"only/except" isn't being actively developed in GitLab.

Use $CI_PIPELINE_SOURCE==push to evaluate "rules:changes" only on
push. In most other cases, "rules:changes" evaluate to true so
checking CI_PIPELINE_SOURCE is important.

Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 .gitlab-ci.yml                       |  2 ++
 automation/build/Makefile            |  4 ++--
 automation/gitlab-ci/containers.yaml | 25 +++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 2 deletions(-)
 create mode 100644 automation/gitlab-ci/containers.yaml

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c8bd7519d5..c5d499b321 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,7 +1,9 @@
 stages:
   - build
   - test
+  - containers
 
 include:
   - 'automation/gitlab-ci/build.yaml'
   - 'automation/gitlab-ci/test.yaml'
+  - 'automation/gitlab-ci/containers.yaml'
diff --git a/automation/build/Makefile b/automation/build/Makefile
index 4df43b0407..5515938878 100644
--- a/automation/build/Makefile
+++ b/automation/build/Makefile
@@ -16,9 +16,9 @@ help:
 include yocto/yocto.inc
 
 %: %.dockerfile ## Builds containers
-	$(DOCKER_CMD) build --pull -t $(REGISTRY)/$(@D):$(@F) -f $< $(<D)
+	$(DOCKER_CMD) build --pull -t $(REGISTRY)/$(@D):$(@F)$(BUILD_CONTAINER_SUFFIX) -f $< $(<D)
 	@if [ ! -z $${PUSH+x} ]; then \
-		$(DOCKER_CMD) push $(REGISTRY)/$(@D):$(@F); \
+		$(DOCKER_CMD) push $(REGISTRY)/$(@D):$(@F)$(BUILD_CONTAINER_SUFFIX); \
 	fi
 
 .PHONY: all clean
diff --git a/automation/gitlab-ci/containers.yaml b/automation/gitlab-ci/containers.yaml
new file mode 100644
index 0000000000..ace93eaccf
--- /dev/null
+++ b/automation/gitlab-ci/containers.yaml
@@ -0,0 +1,25 @@
+.container-build-tmpl:
+  stage: containers
+  image: docker:stable
+  tags:
+    - container-builder
+  rules:
+    - if: $CI_PIPELINE_SOURCE == "push" && $CI_COMMIT_BRANCH == "staging"
+      changes:
+        - automation/build/${BUILD_CONTAINER}.dockerfile
+  services:
+    - docker:dind
+  before_script:
+    - apk add make
+    - docker info
+    - docker login -u $CI_DEPLOY_USER -p $CI_DEPLOY_PASSWORD $CI_REGISTRY
+  script:
+    - make -C automation/build ${BUILD_CONTAINER} PUSH=1 BUILD_CONTAINER_SUFFIX=-test
+  after_script:
+    - docker logout
+
+debian-unstable-container:
+  extends:
+    - .container-build-tmpl
+  variables:
+    BUILD_CONTAINER: debian/unstable
-- 
Anthony PERARD