According to the documentation to be able to use --cache-from for
remote registries you need to enable both buildkit and inline the
metadata. We want to do this to support pulling from gitlab when users
build their local docker images.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 .gitlab-ci.d/containers.yml | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/.gitlab-ci.d/containers.yml b/.gitlab-ci.d/containers.yml
index 2afd01f1d17..f353359fd8b 100644
--- a/.gitlab-ci.d/containers.yml
+++ b/.gitlab-ci.d/containers.yml
@@ -11,7 +11,9 @@
   script:
     - docker pull "$TAG" || docker pull "$COMMON_TAG" || true
     - sed -i -e "s,FROM qemu/,FROM $CI_REGISTRY_IMAGE/qemu/," tests/docker/dockerfiles/$NAME.docker
-    - docker build --cache-from "$TAG" --cache-from "$COMMON_TAG" --tag "$TAG" -f "tests/docker/dockerfiles/$NAME.docker" tests/docker/dockerfiles
+    - DOCKER_BUILDKIT=1 docker build --cache-from "$TAG" --cache-from "$COMMON_TAG" --tag "$TAG"
+                                     --build-arg BUILDKIT_INLINE_CACHE=1
+                                     -f "tests/docker/dockerfiles/$NAME.docker" tests/docker/dockerfiles
     - docker push "$TAG"
   after_script:
     - docker logout
-- 
2.20.1