Rebuild docker images only when they are modified

Makefile

DOCKER_COMPOSE?=docker-compose
DOCKER_FILES=$(shell find ./docker/dev/ -type f -name '*')

.DEFAULT_GOAL := help

.PHONY: help
help:
	@grep -E '(^[a-zA-Z_-]+:.*?##.*$$)|(^##)' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[32m%-30s\033[0m %s\n", $$1, $$2}' | sed -e 's/\[32m##/[33m/'

##
## Project setup
##---------------------------------------------------------------------------

.PHONY: start
start: build up ## Start docker containers

.PHONY: stop
stop: ## Remove and stop docker containers
	$(DOCKER_COMPOSE) kill
	$(DOCKER_COMPOSE) rm -v --force

.PHONY: reset
reset: stop clear start

.PHONY: clear
clear:
	rm -f docker-dev.lock

##
# Internal rules
##

.PHONY: build
build: docker-dev.lock

docker-dev.lock: $(DOCKER_FILES)
	$(DOCKER_COMPOSE) pull --parallel --ignore-pull-failures
	$(DOCKER_COMPOSE) build --pull --force-rm
	touch docker-dev.lock

.PHONY: up
up:
	$(DOCKER_COMPOSE) up -d --remove-orphans