playground: use the correct contexts for sandbox requests

The sandbox code was incorrectly using the request context instead of
the build context when trying to determine if there was a
DeadlineExceeded error. This would manifest to the user as a blank
response in the build output, rather than the correct error.

Additionally, the sandbox code was using the incorrect context for
running the binary. This means we were not correctly enforcing

Finally, tests do not pass with a maxRunTime of 2 seconds on my machine,
and it's unclear what impact enforcing this would have on production
code. I've increased it to 5 seconds. It would be prudent to add metrics
here to determine how user programs are impacted in a follow-up issue.

Updates golang/go#25224
Updates golang/go#38052

Change-Id: I59aa8caeb63a9eec687bfbe4f69c57f71a13440d
Reviewed-by: Andrew Bonventre <>
Reviewed-by: Bryan C. Mills <>
1 file changed
tree: e646ab5ea4cfd66cd0e5b9abebd869980460ceb1
  1. cmd/
  2. deploy/
  3. examples/
  4. internal/
  5. sandbox/
  6. static/
  7. .gitignore
  8. app.yaml
  10. cache.go
  11. client.go
  12. codereview.cfg
  15. Dockerfile
  16. edit.go
  17. edit.html
  18. enable-fake-time.patch
  19. fake_fs.lst
  20. fmt.go
  21. fmt_test.go
  22. go.mod
  23. go.sum
  25. logger.go
  26. main.go
  27. Makefile
  29. play.go
  30. play_test.go
  32. sandbox.go
  33. server.go
  34. server_test.go
  35. share.go
  36. store.go
  37. tests.go
  38. txtar.go
  39. txtar_test.go
  40. vet.go


This subrepository holds the source for the Go playground:


# build the image
docker build -t 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