internal/metrics: fix detection of GCE environment

appengine.IsAppEngine mistakenly returns false, as it relies on the app
being built with the appenginevm build constraint. This is not set,
as we're supplying our own Docker image.

The playground is always running either locally or on appengine. We can
rely on metadata.OnGCE being correct.

Other calls that are made to the appengine library either use the
metadata server or environment variables, and do not rely on a
constraint being set. They also panic if the metadata server is

For golang/go#44822

Change-Id: I1de5fda4bfd1e909f1fd54cc44770525827a9c1a
Trust: Alexander Rakoczy <>
Run-TryBot: Alexander Rakoczy <>
TryBot-Result: Go Bot <>
Reviewed-by: Dmitri Shuralyov <>
3 files changed
tree: ea9a73b3f8cb4d43b4f111b720cc9157af8dadd5
  1. .gitignore
  5. Dockerfile
  7. Makefile
  10. app.yaml
  11. cache.go
  12. client.go
  13. cmd/
  14. codereview.cfg
  15. deploy/
  16. edit.go
  17. edit.html
  18. enable-fake-time.patch
  19. examples/
  20. fake_fs.lst
  21. fmt.go
  22. fmt_test.go
  23. go.mod
  24. go.sum
  25. internal/
  26. logger.go
  27. main.go
  28. metrics.go
  29. play.go
  30. play_test.go
  31. sandbox.go
  32. sandbox/
  33. sandbox_test.go
  34. server.go
  35. server_test.go
  36. share.go
  37. static/
  38. store.go
  39. tests.go
  40. txtar.go
  41. txtar_test.go
  42. vet.go


Go Reference

This subrepository holds the source for the Go playground:


# build the image
docker build -t golang/playground .


docker run --name=play --rm -p 8080:8080 golang/playground &
# run some Go code
cat /path/to/code.go | go run client.go | curl -s --upload-file - localhost:8080/compile


Deployment Triggers

Playground releases automatically triggered when new Go repository tags are pushed to GitHub, or when master is pushed on the playground repository.

For details, see deploy/go_trigger.json, deploy/playground_trigger.json, and deploy/deploy.json.

After making changes to trigger configuration, update configuration by running the following Make target:

make update-cloudbuild-trigger

Deploy via Cloud Build

The Cloud Build configuration will always build and deploy with the latest supported release of Go.

gcloud builds submit --config deploy/deploy.json .

Deploy via gcloud app deploy

Building the playground Docker container takes more than the default 10 minute time limit of cloud build, so increase its timeout first (note, app/cloud_build_timeout is a global configuration value):

gcloud config set app/cloud_build_timeout 1200  # 20 mins

Alternatively, to avoid Cloud Build and build locally:

make docker
docker tag golang/playground:latest
docker push
gcloud --project=golang-org app deploy app.yaml


gcloud --project=golang-org app deploy app.yaml


To submit changes to this repository, see