Improve dind caching

.gitlab-ci.yml

@@ -19,7 +19,8 @@ stages:
     - docker info
   script:
     - docker login -u gitlab-ci-token -p $CI_BUILD_TOKEN $CI_REGISTRY
-    - docker build -t "$IMAGE_TAG" "scripts/docker/$IMAGE_NAME"
+    - docker pull "$IMAGE_TAG" || true
+    - docker build --cache-from "$IMAGE_TAG" -t "$IMAGE_TAG" "scripts/docker/$IMAGE_NAME"
     - docker push "$IMAGE_TAG"
   tags:
     - dind
@@ -45,7 +46,7 @@ docker:knot-dns:ubuntu:
 docker:knot-dns:centos:
   <<: *image
   variables:
-    IMAGE_NAME: centos:latestf
+    IMAGE_NAME: centos:latest
     IMAGE_TAG: $CI_REGISTRY_IMAGE/$IMAGE_NAME
 
 docker:knot-dns:fedora: