CI: use wayland-ci-templates to manage the images

There shouldn't be a difference for users, but this way we do manage
all of our containers from freedesktop.org

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Reviewed-by: Michel Dänzer <michel.daenzer@amd.com>

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-# IMAGE_TAG is the tag of the docker image used for the build jobs. If the
+# DEBIAN_TAG is the tag of the docker image used for the build jobs. If the
 # image doesn't exist yet, the docker-image stage generates it.
 #
 # In order to generate a new image, one should generally change the tag.
@@ -13,40 +13,25 @@
 # container registry, so that the image from the main repository's registry
 # will be used there as well.
 variables:
-    IMAGE_TAG: "debian-testing-20190219"
-    IMAGE_LOCAL: "$CI_REGISTRY_IMAGE:$IMAGE_TAG"
-    IMAGE_MAIN: "registry.freedesktop.org/xorg/xserver:$IMAGE_TAG"
+    UPSTREAM_REPO: xorg/xserver
+    DEBIAN_VERSION: testing-slim
+    DEBIAN_EXEC: 'bash .gitlab-ci/debian-install.sh'
+
+    DEBIAN_TAG: "2019-03-27"
+    IMAGE_LOCAL: "$CI_REGISTRY_IMAGE/debian/$DEBIAN_VERSION:$DEBIAN_TAG"
+
+include:
+  - project: 'wayland/ci-templates'
+    ref: c73dae8b84697ef18e2dbbf4fed7386d9652b0cd
+    file: '/templates/debian.yml'
 
 stages:
     - docker-image
     - build-and-test
 
 debian-testing:
-    stage: docker-image
-    image:
-        name: gcr.io/kaniko-project/executor:debug
-        entrypoint: [""]
-    script:
-        - echo "{\"auths\":{\"$CI_REGISTRY\":{\"username\":\"$CI_REGISTRY_USER\",\"password\":\"$CI_REGISTRY_PASSWORD\"}}}" > /kaniko/.docker/config.json
-        - mkdir kaniko-context
-        - |
-          echo "FROM $IMAGE_LOCAL" > kaniko-context/Dockerfile
-          # If the image exists in the local registry, skip to the build-and-test job
-          set +e
-          set -x
-          /kaniko/executor --context kaniko-context --no-push && exit 0
-          set +x
-          set -e
-        - |
-          echo "FROM $IMAGE_MAIN" > kaniko-context/Dockerfile
-          # Try to re-use the image from the main repository's registry, and if
-          # that fails, generate a local image from scratch
-          set +e
-          set -x
-          /kaniko/executor --context kaniko-context --destination $IMAGE_LOCAL && exit 0
-          set +x
-          set -e
-        - /kaniko/executor --context $CI_PROJECT_DIR/.gitlab-ci --destination $IMAGE_LOCAL
+  extends: .debian@container-ifnot-exists
+  stage: docker-image
 
 .common-build-and-test:
     stage: build-and-test