build/docker: Reuse tagged image for OPNFV build

During CI build loops, the workspace is freshly fetched,
so '.docker' make target is built each time.

Reuse existing 'opnfv.org/ubuntu-builder:14.04' tag if present, but
enforce a configurable lifespan for this tag (currently 1 day), so
it does not get stale.

JIRA: FUEL-204

Change-Id: I8d1bd81f3e5e81068e9586c9bea9f43b3327eb38
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

3 files changed, 70 insertions, 7 deletions

diff --git a/build/cache.mk b/build/cache.mk
index f6db01797..a65f310d0 100644
--- a/build/cache.mk
+++ b/build/cache.mk
@@ -51,5 +51,5 @@ cache:
 		exit 1; \
 	fi
 	@docker version >/dev/null 2>&1 || (echo 'No Docker installation available'; exit 1)
-	@make -C docker
+	@make -C docker get-cache all
 	docker/runcontext $(DOCKERIMG) $(MAKE) $(MAKEFLAGS) cached-all
diff --git a/build/docker/.gitignore b/build/docker/.gitignore
new file mode 100644
index 000000000..2585910ce
--- /dev/null
+++ b/build/docker/.gitignore
@@ -0,0 +1,2 @@
+.docker*
+ubuntu-builder/Dockerfile
diff --git a/build/docker/Makefile b/build/docker/Makefile
index d4423b0a2..ab7a169eb 100644
--- a/build/docker/Makefile
+++ b/build/docker/Makefile
@@ -1,5 +1,5 @@
 ##############################################################################
-# Copyright (c) 2015 Ericsson AB and others.
+# Copyright (c) 2015,2016 Ericsson AB and others.
 # stefan.k.berg@ericsson.com
 # jonas.bjurel@ericsson.com
 # All rights reserved. This program and the accompanying materials
@@ -12,6 +12,15 @@ SHELL = /bin/bash
 FILES = $(wildcard ubuntu-builder/*) runcontext
 DOCKER_VER := $(shell [[ "$$(docker version --format '{{.Client.Version}}')" =~ ([0-9]+)\.([0-9]+) ]] && echo $$(( $${BASH_REMATCH[1]} * 100 + $${BASH_REMATCH[2]} )))
 
+# Builder tag lifespan, force container rebuild X days after tag creation
+DOCKER_KEEP = 1 days
+DOCKER_IMG  = opnfv.org/ubuntu-builder
+DOCKER_TAG  = ${DOCKER_IMG}:14.04
+# Shell contruct for checking our tag object did not expire
+DOCKER_EXPIRED = D_TAG_BIRTH=`docker inspect --format="{{.Created}}" \
+	${DOCKER_TAG} 2>/dev/null`; test -z "$$D_TAG_BIRTH" -o `date +%s` -gt \
+	`date -d "$$D_TAG_BIRTH +${DOCKER_KEEP}" +%s`; echo $$?
+
 # Don't use -f flag when docker is newer than 1.9
 # https://docs.docker.com/engine/deprecated/#/f-flag-on-docker-tag
 ifeq ($(shell echo "$(DOCKER_VER)>109" | bc), 1)
@@ -23,7 +32,7 @@ endif
 .PHONY: all
 all:	.docker
 
-.docker: $(FILES)
+.dockercfg: $(FILES)
 	cp Dockerfile ubuntu-builder/Dockerfile
 	# Only add proxy ENVs where set in host - needed to pull the base Ubuntu image
 	test -n "${http_proxy}" && sed -i "s;INSERT_HTTP_PROXY;${http_proxy};" ubuntu-builder/Dockerfile || exit 0
@@ -33,10 +42,62 @@ all:	.docker
 	test -n "${HTTPS_PROXY}" && sed -i "s;INSERT_HTTPS_PROXY;${HTTPS_PROXY};" ubuntu-builder/Dockerfile || exit 0
 	test -n "${NO_PROXY}" && sed -i "s;INSERT_NO_PROXY;${NO_PROXY};" ubuntu-builder/Dockerfile || exit 0
 	sed -i '/INSERT_/d' ubuntu-builder/Dockerfile
-	/usr/bin/docker build --rm=true --no-cache=true -t opnfv.org/ubuntu-builder:14.04 ubuntu-builder
-	/usr/bin/docker tag ${tag_flags} opnfv.org/ubuntu-builder:14.04 opnfv.org/ubuntu-builder
-	touch .docker
+	touch $@
+
+.docker: .dockercfg
+	@if test "$(shell ${DOCKER_EXPIRED})" -eq "0"; then \
+		/usr/bin/docker build --rm=true --no-cache=true \
+			-t ${DOCKER_TAG} ubuntu-builder && \
+		/usr/bin/docker tag ${tag_flags} ${DOCKER_TAG} ${DOCKER_IMG}; \
+	else \
+		echo "Docker: Tag '${DOCKER_TAG}' was created less than" \
+			"${DOCKER_KEEP} ago, skipping re-build."; \
+	fi
+	touch $@
+	test -f .cacheid && $(MAKE) -f Makefile put-cache || exit 0
 
 .PHONY:	clean
 clean:
-	rm -f .docker ubuntu-builder/Dockerfile
+	rm -f .docker* ubuntu-builder/Dockerfile
+
+.PHONY: deepclean
+deepclean: clean clean-cache
+
+##############################################################################
+# Cache operations - only used when building through ci/build.sh
+##############################################################################
+
+# NOTE: For docker, we only get/put cache to fingerprint build scripts and
+# env vars, its cached data holds only an empty .docker file.
+
+# Create a unique hash to be used for getting and putting cache, based on:
+#   - ubuntu-builder Dockerfile (includes eventual proxy env vars), runcontext;
+#   - The contents of this Makefile
+.cacheid: .dockercfg
+	sha1sum Makefile runcontext $(wildcard ubuntu-builder/*) > .cachedata
+	cat .cachedata | $(CACHETOOL) getid > .cacheid
+
+# Clean local data related to caching - called prior to ordinary build
+.PHONY: clean-cache
+clean-cache:
+	rm -f .cachedata .cacheid
+
+# Try to download cache - called prior to ordinary build
+.PHONY: get-cache
+get-cache: .cacheid
+	@if $(CACHETOOL) check $(shell cat .cacheid); then \
+		if test "$(shell ${DOCKER_EXPIRED})" -eq "0"; then \
+			echo "Docker: Tag '${DOCKER_TAG}' missing" \
+				"or older than ${DOCKER_KEEP}, not using it."; \
+		else \
+			touch .docker; \
+		fi; \
+	else \
+		echo "No cache item found for $(shell cat .cacheid)" ;\
+		exit 0;\
+	fi
+
+# Store cache if not already stored - called after ordinary build
+.PHONY: put-cache
+put-cache: .cacheid
+	@tar cf - .docker | $(CACHETOOL) put $(shell cat .cacheid)