x/website: make it safer to make changes to draft release notes

[dmitshur]

Right now we rely on https://tip.golang.org (served by the golang.org/x/build/cmd/tip command), the server that automatically deploys and serves the latest x/website and Go repository commits, for sharing draft release notes such as at https://tip.golang.org/doc/go1.14.

Always showing the latest Go+x/website commits means that changes to the draft release notes are previewed very quickly, which is great for seeing the latest state and for spotting problems very quickly. However, release notes use template processing, and if there is an error in the template, an error is displayed. That makes editing the draft release notes a risky process, which can cause times where draft release notes can't be viewed (see #37070 recently).

We should find a way to make the process safer, but hopefully without negatively affecting the convenience of being able to see the latest commits without manual effort.

/cc @golang/osp-team

[dmitshur]

Given that the release notes are largely HTML (with a minor template component) inside the doc directory of the main Go repository, and so people often rightfully do not run trybots before submitting changes. A good solution to this should take that into account.

[dmitshur]

I've searched through the release notes for many Go releases, and I'm seeing that most of them do not actually use the template functionality for anything, other than to escape {{ and }} itself. So a good solution may be to turn off the template functionality, and enable it only when it is needed.

I see that go1.html uses templates quite a bit:

doc/go1.html:
   62  </p>
   63  
   64: {{code "/doc/progs/go1.go" `/greeting := ..byte/` `/append.*hello/`}}
   65  
   66  <p>
   ..
   71  </p>
   72  
   73: {{code "/doc/progs/go1.go" `/append.*world/`}}
   74  
   75  <p>
   ..
  121  </p>
  122  
  123: {{code "/doc/progs/go1.go" `/type Date struct/` `/STOP/`}}
  124  
  125  <p>
   ..

But none of the other releases (1.1 through 1.14) do.

[gopherbot]

Change https://golang.org/cl/218058 mentions this issue: doc/go1.14: disable text/template processing in HTML page

[bcmills]

people often rightfully do not run trybots before submitting changes

#37047 is closely related, in that it would also (ideally) detect issues in generated HTML during TryBot runs.

[gopherbot]

Change https://golang.org/cl/218217 mentions this issue: content/static/doc: escape template brackets in code.html

[bcmills]

This just bit me on CL 217877, too — and it did have a TryBot +1.

I think we really do need to test the rendered templates in some form. (Reopening.)