Makefile allow to use external docker image instead of building locally via DOCKER_IMAGE env var

Author: krezreb

docker/Makefile

@@ -5,13 +5,23 @@ else
 FORCE_WRITE := false
 endif
 
+
+
+
+
 SHELL := /bin/bash
 
 .PHONY: build generate serve clean reset-permissions confirm-clean env-file-exists ca-key-exists
 
 # Build a new docker image for the CA bot
 build: reset-permissions
+ifdef DOCKER_IMAGE
+	docker pull $(DOCKER_IMAGE)
+	docker tag $(DOCKER_IMAGE) ca
+else
 	docker build -t ca -f Dockerfile-ca ..
+endif
+
 
 # Generate a new CA key
 generate: env-file-exists build