cmd/godoc: add `make publish` to migrate traffic

Also rename `make build` and `make push` to `make docker-build` and
`make docker-push` in preparation to introduce Cloud Build (removing
the dependency on Docker).

Updates golang/go#27205.

Change-Id: Iae19b9a6f77d09246a1332c7ec9eceec449cdba8
Reviewed-on: https://go-review.googlesource.com/c/139239
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

cmd/godoc/Makefile

@@ -19,7 +19,7 @@ usage:
 	@echo "See Makefile and README.godoc-app"
 	@exit 1
 
-docker: Dockerfile.prod
+docker-build: Dockerfile.prod
 	# NOTE(cbro): move up in directory to include entire tools repo.
 	cd ../..; docker build \
 		-f cmd/godoc/Dockerfile.prod \
@@ -30,24 +30,42 @@ docker: Dockerfile.prod
 		--tag=$(DOCKER_TAG) \
 		.
 
-push: docker
+docker-push: docker-build
 	docker push $(DOCKER_TAG)
 
-deploy: push
+deploy:
 	gcloud -q app deploy app.prod.yaml \
-		--project $(GCP_PROJECT) \
+		--project=$(GCP_PROJECT) \
 		--no-promote \
-		--image-url $(DOCKER_TAG)
+		--image-url=$(DOCKER_TAG)
 
 get-latest-url:
 	@gcloud app versions list \
-		-s default \
-		--project $(GCP_PROJECT) \
+		--service=default \
+		--project=$(GCP_PROJECT) \
 		--sort-by=~version.createTime \
 		--format='value(version.versionUrl)' \
 		--limit 1 | cut -f1 # NOTE(cbro): gcloud prints out createTime as the second field.
 
+get-latest-id:
+	@gcloud app versions list \
+		--service=default \
+		--project=$(GCP_PROJECT) \
+		--sort-by=~version.createTime \
+		--format='value(version.id)' \
+		--limit 1 | cut -f1 # NOTE(cbro): gcloud prints out createTime as the second field.
+
 regtest:
 	go test -v \
 		-regtest.host=$(shell make get-latest-url) \
 		-run=Live
+
+publish: regtest
+	gcloud -q app services set-traffic default \
+		--splits=$(shell make get-latest-id)=1 \
+		--project=$(GCP_PROJECT)
+
+	@echo !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
+	@echo Stop and/or delete old versions:
+	@echo "https://console.cloud.google.com/appengine/versions?project=$(GCP_PROJECT)&serviceId=default&versionssize=50"
+	@echo !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

cmd/godoc/README.godoc-app

@@ -37,7 +37,7 @@ Running locally, in production mode, using Docker
 
 Build the app's Docker container:
 
-  make docker
+  make docker-build
 
 Make sure redis is running on port 6379:
 
@@ -68,17 +68,19 @@ Deploying to golang.org
 
 Build the image, push it to gcr.io, and deploy to Flex:
 
-  make deploy
+  make docker-push deploy
 
-Run regression tests:
+Point the load balancer to the newly deployed version:
+(This also runs regression tests)
 
-  make regtest
+  make publish
 
-Go to the console to migrate traffic to the newly deployed version:
+Stop and/or delete down any very old versions. (Stopped versions can be re-started.)
+Keep at least one older verson to roll back to, just in case.
+You can also migrate traffic to the new version via this UI.
 
   https://console.cloud.google.com/appengine/versions?project=golang-org&serviceId=default&versionssize=50
 
-Shut down any very old versions (keep at least one to roll back to, just in case).
 
 Troubleshooting
 ---------------