Grab different etcd versions in etcd image.

cluster/images/etcd/Dockerfile

@@ -16,4 +16,5 @@ FROM BASEIMAGE
 MAINTAINER Dawn Chen <dawnchen@google.com>
 
 EXPOSE 2379 2380 4001 7001
-COPY etcd etcdctl migrate-if-needed.sh attachlease /usr/local/bin/
+COPY etcd* etcdctl* /usr/local/bin/
+COPY migrate-if-needed.sh attachlease /usr/local/bin/

cluster/images/etcd/Makefile

@@ -15,10 +15,19 @@
 # Build the etcd image
 #
 # Usage:
-# 	[TAG=3.0.4] [REGISTRY=gcr.io/google_containers] [ARCH=amd64] [BASEIMAGE=busybox] make (build|push)
+# 	[TAGS=2.2.1 2.3.7 3.0.10] [REGISTRY=gcr.io/google_containers] [ARCH=amd64] [BASEIMAGE=busybox] make (build|push)
 
-TAG?=3.0.4
-REGISTRY_TAG?=$(TAG)
+# The image contains different etcd versions to simplify
+# upgrades. Thus be careful when removing any tag from here.
+#
+# NOTE: The etcd upgrade rules are that you can upgrade only 1 minor
+# version at a time, and patch release don't matter.
+#
+# Except from etcd-$(tag) and etcdctl-$(tag) binaries, we also
+# need etcd and etcdctl binaries for backward compatibility reasons.
+# That binary will be set to the last tag from $(TAGS).
+TAGS?=2.2.1 2.3.7 3.0.10
+REGISTRY_TAG?=3.0.10
 ARCH?=amd64
 REGISTRY?=gcr.io/google_containers
 GOLANG_VERSION?=1.6.3
@@ -50,16 +59,30 @@ build:
 ifeq ($(ARCH),amd64)
 
 	# Do not compile if we should make an image for amd64, use the official etcd binaries instead
-	curl -sSL --retry 5 https://github.com/coreos/etcd/releases/download/v$(TAG)/etcd-v$(TAG)-linux-amd64.tar.gz | tar -xz -C $(TEMP_DIR) --strip-components=1
+	# For each release create a tmp dir 'etcd_release_tmp_dir' and unpack the release tar there.
+	for tag in $(TAGS); do \
+		etcd_release_tmp_dir=$(shell mktemp -d); \
+		curl -sSL --retry 5 https://github.com/coreos/etcd/releases/download/v$$tag/etcd-v$$tag-linux-amd64.tar.gz | tar -xz -C $$etcd_release_tmp_dir --strip-components=1; \
+		cp $$etcd_release_tmp_dir/etcd $$etcd_release_tmp_dir/etcdctl $(TEMP_DIR)/; \
+		cp $(TEMP_DIR)/etcd $(TEMP_DIR)/etcd-$$tag; \
+		cp $(TEMP_DIR)/etcdctl $(TEMP_DIR)/etcdctl-$$tag; \
+	done
 else
 	
 	# Download etcd in a golang container and cross-compile it statically
-	docker run -it -v $(TEMP_DIR):/etcdbin golang:$(GOLANG_VERSION) /bin/bash -c \
-		"git clone https://github.com/coreos/etcd /go/src/github.com/coreos/etcd \
-		&& cd /go/src/github.com/coreos/etcd \
-		&& git checkout v$(TAG) \
-		&& GOARM=$(GOARM) GOARCH=$(ARCH) ./build \
-		&& cp -f bin/$(ARCH)/etcd* bin/etcd* /etcdbin; echo 'done'"
+	# For each release create a tmp dir 'etcd_release_tmp_dir' and unpack the release tar there.
+	for tag in $(TAGS); do \
+		etcd_release_tmp_dir=$(shell mktemp -d); \
+		docker run -it -v $$etcd_release_tmp_dir:/etcdbin golang:$(GOLANG_VERSION) /bin/bash -c \
+			"git clone https://github.com/coreos/etcd /go/src/github.com/coreos/etcd \
+			&& cd /go/src/github.com/coreos/etcd \
+			&& git checkout v$$tag \
+			&& GOARM=$(GOARM) GOARCH=$(ARCH) ./build \
+			&& cp -f bin/$(ARCH)/etcd* bin/etcd* /etcdbin; echo 'done'"; \
+		cp $$etcd_release_tmp_dir/etcd $$etcd_release_tmp_dir/etcdctl $(TEMP_DIR)/; \
+		cp $(TEMP_DIR)/etcd $(TEMP_DIR)/etcd-$$tag; \
+		cp $(TEMP_DIR)/etcdctl $(TEMP_DIR)/etcdctl-$$tag; \
+	done
 
 	# Add this ENV variable in order to workaround an unsupported arch blocker
 	# The multiarch feature is in an limited and experimental state right now, and etcd should work fine on arm64