Merge pull request #9635 from cladmi/pr/docker/allow_using_sudo

makefiles/docker.inc.mk: allow using sudo for docker

makefiles/docker.inc.mk

@@ -79,6 +79,9 @@ DOCKER_OVERRIDE_CMDLINE := $(foreach varname,$(DOCKER_ENV_VARS), \
     ))
 DOCKER_OVERRIDE_CMDLINE := $(strip $(DOCKER_OVERRIDE_CMDLINE))
 
+# Overwrite if you want to use `docker` with sudo
+DOCKER ?= docker
+
 # This will execute `make $(DOCKER_MAKECMDGOALS)` inside a Docker container.
 # We do not push the regular $(MAKECMDGOALS) to the container's make command in
 # order to only perform building inside the container and defer executing any
@@ -88,7 +91,7 @@ DOCKER_OVERRIDE_CMDLINE := $(strip $(DOCKER_OVERRIDE_CMDLINE))
 # hardware which may not be reachable from inside the container.
 ..in-docker-container:
 	@$(COLOR_ECHO) '$(COLOR_GREEN)Launching build container using image "$(DOCKER_IMAGE)".$(COLOR_RESET)'
-	docker run $(DOCKER_FLAGS) -t -u "$$(id -u)" \
+	$(DOCKER) run $(DOCKER_FLAGS) -t -u "$$(id -u)" \
 	    -v '$(RIOTBASE):$(DOCKER_BUILD_ROOT)/riotbase' \
 	    -v '$(RIOTCPU):$(DOCKER_BUILD_ROOT)/riotcpu' \
 	    -v '$(RIOTBOARD):$(DOCKER_BUILD_ROOT)/riotboard' \