optimize makefile, rebuild only if files changed

Dockerfile

@@ -23,7 +23,7 @@ RUN apt-get update -qq && \
 # Copy application code
 COPY . .
 
-RUN npm i -g webpack-cli pm2
+RUN npm i -g webpack-cli
 RUN npm ci
 RUN npm run dist:all
 
@@ -35,4 +35,4 @@ COPY --from=build /app /app
 
 # Start the server by default, this can be overwritten at runtime
 EXPOSE 3000
-CMD [ "npm", "run", "pm2"]
+CMD [ "npm", "start"]

Makefile

@@ -1,61 +1,34 @@
+demos = monaco codemirror codemirror.next prosemirror prosemirror-versions quill
 
+all : $(demos)
 
-all :
-	make -j demos
+# remove all generated files
+clean :
+	rm -rf */dist */node_modules node_modules
 
-static-content : all
+static-content :
+	make -j all
 	rm -rf node_modules */node_modules
 
-demos: monaco cm cm6 pm pm-versions quill
-
-node_modules :
-	npm ci
-
-# build demo-server
-demo-server :
-	cd demo-server
-	npm ci
-.PHONY demo-server
-
-# build codemirror 5 demo
-cm : node_modules
-	cd codemirror
-	npm ci
-	npm run dist
-
-# build codemirror 6 demo
-cm6 : node_modules
-	cd codemirror.next
-	npm ci
-	npm run dist
-
-# build prosemirror demo
-pm : node_modules
-	cd prosemirror
-	npm ci
-	npm run dist
-
-# build prosemirror-versions demo
-pm-versions : node_modules
-	cd prosemirror-versions
-	npm ci
-	npm run dist
-
-# build quill demo
-quill : node_modules
-	cd quill
-	npm ci
-	npm run dist
-
-# build monaco demo
-monaco : node_modules
-	cd monaco
-	npm ci
-	npm run dist
-.PHONY : monaco
+$(demos) : % : %/dist
+.PHONY : $(demos)
 
-# remove all generated files
-clean :
-	rm -rf */dist */node_modules node_modules
+%/node_modules: %/package.json %/package-lock.json
+	cd $* && npm ci
+	touch $@
+
+.NOTINTERMEDIATE: $(patsubst %,%/node_modules,$(demos))
+
+node_modules : package.json package-lock.json
+	-npm ci
+	-touch node_modules
+
+.SECONDEXPANSION:
+%/dist : node_modules %/node_modules $$(filter-out %/dist %/node_modules,$$(wildcard $$*/*))
+	cd $* && npm run dist
+	touch $@
+
+.PHONY: serve
+serve : $(demos) demo-server/node_modules
+	cd demo-server && npm start
 
-.ONESHELL :