playground: use stdlib instead of appengine packages

With modern versions of App Engine, it's no longer needed to use the
google.golang.org/appengine/... packages.

Package log from standard library can be used instead of the
google.golang.org/appengine/log package. Packages net/http and
context from standard library can be used instead of
google.golang.org/appengine/urlfetch.

This simplifies the code and reduces the number of dependences.

Start using the golangorgenv package from previous commit to
make the decision of whether to enforce sharing restrictions,
rather than relying on the appengine build tag. The appengine
build tag is no longer set in App Engine Standard with Go 1.11+
runtime. An alternative solution would be detect App Engine by
doing something like:

	// GAE_ENV environment variable is set to "standard" in App Engine environment, Go 1.11 runtime.
	// See https://cloud.google.com/appengine/docs/standard/go111/runtime#environment_variables.
	var onAppengine = os.Getenv("GAE_ENV") == "standard"

But we choose to upgrade to explicit app-scoped environment variable
configuration as part of this change. It provides better security
properties, and the value of adding an intermediate transitional step
is not high enough to justify doing it.

When getting the value of "X-AppEngine-Country" header, use its
canonical format "X-Appengine-Country" to avoid an allocation.
This does not change behavior.

Run go mod tidy (using Go 1.12).

Updates golang/go#29981
Updates golang/go#30486

Change-Id: I82a59e0f28623e06762b7ebdf3930b5ee243acda
Reviewed-on: https://go-review.googlesource.com/c/tools/+/160837
Reviewed-by: Michael Matloob <matloob@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
6 files changed
tree: 5bcabcd9a7b4bf1b35ea410dbef0649692327316
  1. benchmark/
  2. blog/
  3. cmd/
  4. container/
  5. cover/
  6. go/
  7. godoc/
  8. imports/
  9. internal/
  10. playground/
  11. present/
  12. refactor/
  13. third_party/
  14. .gitattributes
  15. .gitignore
  16. AUTHORS
  17. codereview.cfg
  18. CONTRIBUTING.md
  19. CONTRIBUTORS
  20. go.mod
  21. go.sum
  22. LICENSE
  23. PATENTS
  24. README.md
README.md

Go Tools

This subrepository holds the source for various packages and tools that support the Go programming language.

Some of the tools, godoc and vet for example, are included in binary Go distributions.

Others, including the Go guru and the test coverage tool, can be fetched with go get.

Packages include a type-checker for Go and an implementation of the Static Single Assignment form (SSA) representation for Go programs.

Download/Install

The easiest way to install is to run go get -u golang.org/x/tools/.... You can also manually git clone the repository to $GOPATH/src/golang.org/x/tools.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html.

The main issue tracker for the tools repository is located at https://github.com/golang/go/issues. Prefix your issue with “x/tools/(your subdir):” in the subject line, so it is easy to find.