Using --cache-from in build step

.gitlab-ci.yml

@@ -7,7 +7,7 @@ stages:
   - staging
 
 variables:
-  IMAGE_TAG: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME
+  CONTAINER_IMAGE: $CI_REGISTRY_IMAGE:$CI_COMMIT_REF_NAME
   DOCKER_DRIVER: overlay2
 
 # ========================== Build Testing section =========================== #
@@ -114,8 +114,8 @@ build_backend:
     DOCKER_DRIVER: overlay2
   script:
     - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
-    - docker build -t $IMAGE_TAG .
-    - docker tag $IMAGE_TAG $IMAGE_TAG-$CI_COMMIT_SHA
+    - docker build --cache-from $IMAGE_TAG -t "$IMAGE_TAG-$CI_COMMIT_SHA" -t $IMAGE_TAG .
+    - docker push "$IMAGE_TAG-CI_COMMIT_SHA"
     - docker push $IMAGE_TAG
 #  cache:
 #    key: "$CI_JOB_NAME"