Split scripts by ## (and remove comments / whitespace) to facilitate caching, add option for multicore to make

.gitignore

@@ -1,2 +1,3 @@
 /build/Dockerfile
-/build/tmp.*
+/build/tmp.*
+/build/parts/*

build/Makefile

@@ -3,6 +3,7 @@ FROM = debian:jessie
 MODE = minimal
 ARGS = --rm=false --no-cache=false
 PROXY = $(shell ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | cut -d' ' -f1)
+JOBS = 2
 include $(wildcard $(DOCKER_HOME)/build/make/*.mk)
 
 define add
@@ -28,7 +29,7 @@ define runit
 endef
 
 define script
-	$(call execute,scripts/$(1).sh,$(TMP)/$(1).sh)
+	@python3 $(DOCKER_HOME)/build/parts.py $(1) $(FILE) $(TMP)
 endef
 
 all: build bin service clean
@@ -40,19 +41,26 @@ build: prepare base
 ifneq ($(PROXY),)
 	@$(eval ARGS += --build-arg HTTP_PROXY=http://$(PROXY):3142)
 endif
-	@docker build -t $(NAME):$(VERSION) $(ARGS) -f $(FILE) $(DOCKER_HOME)/build
+ifneq ($(JOBS),)
+	@$(eval ARGS += --build-arg JOBS="-j $(JOBS)")
+endif
+	docker build -t $(NAME):$(VERSION) $(ARGS) -f $(FILE) $(DOCKER_HOME)/build
 	@rm ${FILE}
 
 prepare:
 	@$(eval FILE = $(shell mktemp -p $(DOCKER_HOME)/build))
+	@rm $(DOCKER_HOME)/build/tmp.*
 	@echo FROM $(FROM) > ${FILE}
+	@echo 'ARG JOBS="-j $(JOBS)"' >> ${FILE}
 	@echo ENV MODE $(MODE) >> ${FILE}
 	$(call add,config,/build/config)
 	$(call add,init,/opt/init)
 	@echo 'RUN chmod +x /opt/init' >> ${FILE}
+	@mkdir -p $(DOCKER_HOME)/build/parts
 	$(call script,prepare)
 
 clean:
+	@rm -rf $(DOCKER_HOME)/build/parts
 	@rm -f ${FILE}
 	@rm -rf build
 	@rm -rf id_rsa

build/parts.py

@@ -0,0 +1,38 @@
+import sys
+import os
+import re
+
+file = sys.argv[1]
+docker = open(sys.argv[2], 'a')
+tmp = sys.argv[3]
+
+# Remove all normal comments
+path = '{}/build/scripts/{}.sh'.format(os.environ['DOCKER_HOME'], file)
+contents = ''
+for line in open(path):
+    line = line.strip()
+    if len(line) > 0 and not line.startswith('# '):
+        contents += line + '\n'
+
+# Split on comments starting with ##
+parts = re.split('## .*', contents)
+first = parts.pop(0).strip()
+
+# Iterate over parts, except header
+i = 0
+for part in parts:
+    i += 1
+
+    # Add reading environment variables
+    extra = '' if file == 'prepare' else 'export_container_environment\n'
+
+    # Write parts file
+    contents = '{}\n{}{}'.format(first, extra, part)
+    partfile = '{}_{}.sh'.format(file, i)
+    path = '{}/build/parts/{}'.format(os.environ['DOCKER_HOME'], partfile)
+    open(path, 'w').write(contents)
+    os.chmod(path, 0o100)
+
+    # Append to Dockerfile
+    docker.write('ADD parts/{} {}/{}\n'.format(partfile, tmp, partfile))
+    docker.write('RUN {}/{}\n'.format(tmp, partfile))