Merge branch 'base-r-buildkit' into 'base-r'

Use inline cache, BUILDKIT_INLINE_CACHE=1

See merge request !3

.gitlab-ci.yml

@@ -10,10 +10,10 @@ build:
     - echo $CI_REGISTRY_PASSWORD | docker login -u $CI_REGISTRY_USER $CI_REGISTRY --password-stdin
   script:
     # pull the latest example of shiny-k8s image
-    - docker pull "$CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG:latest" || echo "Former image not found, carring on"
+    #- docker pull "$CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG:latest" || echo "Former image not found, carring on"
     # build the image while passing commit SHA and versions, and tagging the image with them
     - docker build
-      --pull
+      --build-arg BUILDKIT_INLINE_CACHE=1
       --cache-from "$CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG:latest"
       --tag "$CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG:latest"
       --tag "$CI_REGISTRY_IMAGE/$CI_COMMIT_REF_SLUG:$CI_COMMIT_SHORT_SHA"