devapp: update README.md to clarify deployment steps

Adds new target in the Makefile to update pod images
on the devapp deployment.

Renames usage of "dev" with "staging"

Change-Id: I9efcf6b873cea5fff84dbffd9129ad3cc6fca7d2
Reviewed-on: https://go-review.googlesource.com/51350
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

devapp/Makefile

@@ -31,14 +31,19 @@ update-deps:
 
 docker-prod: Dockerfile devapp ca-certificates.crt
 	docker build --force-rm --tag=gcr.io/symbolic-datum-552/devapp:$(VERSION) .
-docker-dev: Dockerfile devapp ca-certificates.crt
+docker-staging: Dockerfile devapp ca-certificates.crt
 	docker build --force-rm --tag=gcr.io/go-dashboard-dev/devapp:$(VERSION) .
 
 push-prod: docker-prod
 	gcloud docker -- push gcr.io/symbolic-datum-552/devapp:$(VERSION)
-push-dev: docker-dev
+push-staging: docker-staging
 	gcloud docker -- push gcr.io/go-dashboard-dev/devapp:$(VERSION)
 
+deploy-prod: push-prod
+	kubectl set image deployment/devapp-deployment devapp=gcr.io/symbolic-datum-552/devapp:$(VERSION)
+deploy-staging: push-staging
+	kubectl set image deployment/devapp-deployment devapp=gcr.io/go-dashboard-dev/devapp:$(VERSION)
+
 .PHONY: clean
 clean:
 	$(RM) devapp

devapp/README.md

@@ -11,10 +11,44 @@ Then visit http://localhost:6343
 
 ## Deployment
 
+### Staging
+
 ```sh
-$ gcloud config set project {go-dashboard-dev|symbolic-datum-552}
+$ gcloud config set project go-dashboard-dev
 $ gcloud container clusters get-credentials --zone=us-central1-f go
-$ make push-{dev|prod}
-$ kubectl create -f deployment-{dev|prod}.yaml
-$ kubectl create -f service-{dev|prod}.yaml
+$ make push-staging
+```
+
+If creating the deployment and service the first time:
+
+```sh
+$ kubectl create -f deployment-staging.yaml
+$ kubectl create -f service-staging.yaml
+```
+
+If updating the pod image:
+
+```sh
+$ make deploy-staging
+```
+
+### Prod
+
+```sh
+$ gcloud config set project symbolic-datum-552
+$ gcloud container clusters get-credentials --zone=us-central1-f go
+$ make push-prod
+```
+
+If creating the deployment and service the first time:
+
+```sh
+$ kubectl create -f deployment-prod.yaml
+$ kubectl create -f service-prod.yaml
+```
+
+If updating the pod image:
+
+```sh
+$ make deploy-prod
 ```