Makefile: add check-docker

Author: dannywillems

Makefile

@@ -325,6 +325,15 @@ check-bash: ## Run shellcheck on bash scripts
 	shellcheck ./scripts/**/*.sh -S warning
 	shellcheck ./buildkite/scripts/**/*.sh -S warning
 
+.PHONY: check-docker
+check-docker: ## Run hadolint on Docker files
+ifdef BUILDKITE
+	hadolint dockerfiles/Dockerfile-*
+else
+	docker run --rm -v $(PWD):/workspace -w /workspace \
+		hadolint/hadolint hadolint dockerfiles/Dockerfile-*
+endif
+
 ########################################
 ## Artifacts