Add release Makefile targets

Adds several Makefile targets to help create stable releases. The
top-level one is "make releas" which should be called with a
RELEASE_VERSION variable, e.g.:

make release RELEASE_VERSION=0.3.0

Doing that changes the VERSION file, commits and tags that commit with
the release version. Then, images using both Fedora and CentOS are built
using that version as the tag instead of latest and pushed, finally the
same images are built and pushed also using :latest.

Author: jhrozek

Makefile

@@ -108,9 +108,19 @@ $(GOPATH)/bin/golangci-lint:
 	GOLANGCI_LINT_CACHE=/tmp/golangci-cache $(GOPATH)/bin/golangci-lint version
 	GOLANGCI_LINT_CACHE=/tmp/golangci-cache $(GOPATH)/bin/golangci-lint linters
 
+.PHONY: set-release-tag
+set-release-tag:
+	$(eval IMAGE_TAG = $(VERSION))
+
 .PHONY: image
 image: default-image centos-image fedora-image
 
+.PHONY: release-image
+release-image: set-release-tag default-image centos-image fedora-image push push-fedora
+	# This will ensure that we also push to the latest tag
+	$(eval IMAGE_TAG = latest)
+	$(MAKE) push
+
 .PHONY: default-image
 default-image:
 	$(CONTAINER_RUNTIME) build -f images/Dockerfile.centos -t $(IMAGE_REPO) .
@@ -124,9 +134,13 @@ fedora-image:
 	$(CONTAINER_RUNTIME) build -f images/Dockerfile.fedora -t $(FEDORA_IMAGE_REPO) .
 
 .PHONY: push
-push:
+push: default-image
 	$(CONTAINER_RUNTIME) push $(IMAGE_REPO)
 
+.PHONY: push-fedora
+push-fedora: fedora-image
+	$(CONTAINER_RUNTIME) push $(FEDORA_IMAGE_REPO)
+
 image.tar:
 	$(MAKE) $(TEST_OS)-image && \
 	$(CONTAINER_RUNTIME) save -o image.tar quay.io/security-profiles-operator/$(IMAGE_NAME)-$(TEST_OS):$(IMAGE_TAG); \
@@ -137,3 +151,31 @@ vagrant-up: image.tar ## Boot the vagrant based test VM
 	# Retry in case provisioning failed because of some temporarily unavailable
 	# remote resource (like the VM image)
 	vagrant up || vagrant up || vagrant up
+
+.PHONY: check-release-version
+check-release-version:
+ifndef RELEASE_VERSION
+	$(error RELEASE_VERSION must be defined)
+endif
+
+.PHONY: commit-release-version
+commit-release-version: check-release-version
+	echo $(RELEASE_VERSION) > VERSION
+	git add VERSION
+	git commit -m "Release v$(RELEASE_VERSION)"
+	$(eval VERSION = $(RELEASE_VERSION))
+
+.PHONY: next-version
+next-version:
+	# matches x.y.z where x,y,z are digits and then writes back x.y.99
+	sed -i "s/\([0-9]\+\).\([0-9]\+\).[0-9]\+/\1.\2.99/" VERSION
+	git add VERSION
+	git commit -m "Prepare VERSION for the next release"
+
+.PHONY: tag-release
+tag-release:
+	git tag "v$(VERSION)"
+	git push origin "v$(VERSION)"
+
+.PHONY: release
+release: commit-release-version tag-release release-image next-version