cmd/gopherbot: accept if maintner metadata is ahead of Gerrit API

The purpose of function onLatestCL is to check that maintner data
isn't behind Gerrit's data (as determined by talking to the Gerrit
REST API directly). However, there are some meta commits that the
Gerrit REST API doesn't return a corresponding message to, so
sometimes maintner data is ahead of "latest Gerrit message".

Since ahead is not _behind_, make onLatestCL report positively in
such situations by checking all cl.Metas, not just the latest one.
Do so in reverse order as an optimization (if there's a match, it's
most likely near the end of cl.Metas slice).

An example of such a meta commit is one that updates an uploaded
patch set and sets the Reviewer field:

	$ git show fc20e3671f7b1ff889d5f947b11d7fda0b608751
	commit fc20e3671f7b1ff889d5f947b11d7fda0b608751 (meta/35/111335/meta)
	Author: Gerrit User 14805 <14805@62eb7196-b449-3ce5-99f1-c037f21e1705>
	Date:   Mon Feb 11 17:49:09 2019 +0000

	    Update patch set 6

	    Patch-set: 6
	    Reviewer: Gerrit User 14805 <14805@62eb7196-b449-3ce5-99f1-c037f21e1705>

It has no corresponding message with same ID in the output from a Gerrit
REST API call at
https://go-review.googlesource.com/changes/111335/detail?o=MESSAGES,
nor does it show up visually in the Gerrit UI at
https://go-review.googlesource.com/c/crypto/+/111335.

Before this change (with fix in CL 161977):

	2019/02/11 15:02:33 Reloaded data from log *maintner.netMutSource.
	2019/02/11 15:02:34 https://golang.org/cl/111335 -- remove wait-author; reply from Andreas Auernhammer <...@mail.de>
	2019/02/11 15:02:35 onLatestCL: maintner metadata for CL 111335 is behind; skipping action for now.

After this change:

	2019/02/11 15:06:46 Reloaded data from log *maintner.netMutSource.
	2019/02/11 15:06:46 https://golang.org/cl/111335 -- remove wait-author; reply from Andreas Auernhammer <...@mail.de>
	2019/02/11 15:06:46 [dry run] would remove hashtag 'wait-author' from CL 111335

Updates golang/go#30172

Change-Id: I1575ccffbf8c3edb337f55bf1bf2c96a4a04bbdd
Reviewed-on: https://go-review.googlesource.com/c/161901
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
1 file changed
tree: a18052f928dc8512b09fd6ed941478c16947da28
  1. app/
  2. autocertcache/
  3. buildenv/
  4. buildlet/
  5. cloudfns/
  6. cmd/
  7. dashboard/
  8. devapp/
  9. doc/
  10. env/
  11. envutil/
  12. gerrit/
  13. internal/
  14. kubernetes/
  15. livelog/
  16. maintner/
  17. pargzip/
  18. revdial/
  19. status/
  20. tarutil/
  21. types/
  22. vcs-test/
  23. vendor/
  24. version/
  25. .dockerignore
  26. AUTHORS
  27. build.go
  28. codereview.cfg
  29. CONTRIBUTING.md
  30. CONTRIBUTORS
  31. go.mod
  32. go.sum
  33. LICENSE
  34. PATENTS
  35. README.md
  36. update-deps.sh
  37. update-readmes.go
README.md

Go Build Tools

This subrepository holds the source for various packages and tools that support Go's build system and the development of the Go programming language.

Report Issues / Send Patches

This repository uses Gerrit for code changes. To contribute, see https://golang.org/doc/contribute.html.

The main issue tracker for the blog is located at https://github.com/golang/go/issues. Prefix your issue with “x/build/DIR: ” in the subject line.

Overview

The main components of the Go build system are:

  • The dashboard, in app/, serves https://build.golang.org/. It runs on App Engine and holds the state for which builds passed or failed, and stores the build failure logs for post-submit failures. (Trybot build failure logs are stored elsewhere). The dashboard does not execute any builds on its own.

  • The coordinator, in cmd/coordinator/, serves https://farmer.golang.org/. It runs on GKE and coordinates the whole build system. It finds work to do (both pre-submit “TryBot” work, and post-submit work) and executes builds, allocating machines to run the builds. It is the owner of all machines.

  • The Go package in buildenv/ contains constants for where the dashboard and coordinator run, for prod, staging, and local development.

  • The buildlet, in cmd/buildlet/, is the HTTP server that runs on each worker machine to execute builds on the coordinator's behalf. This runs on every possible GOOS/GOARCH value. The buildlet binaries are stored on Google Cloud Storage and fetched per-build, so we can update the buildlet binary independently of the underlying machine images. The buildlet is the most insecure server possible: it has HTTP handlers to read & write arbitrary content to disk, and to execute any file on disk. It also has an SSH tunnel handler. The buildlet must never be exposed to the Internet. The coordinator provisions buildlets in one of three ways:

    1. by creating VMs on Google Compute Engine (GCE) with custom images configured to fetch & run the buildlet on boot, listening on port 80 in a private network.

    2. by running Linux containers (on either Google Kubernetes Engine or GCE with the Container-Optimized OS image), with the container images configured to fetch & run the buildlet on start, also listening on port 80 in a private network.

    3. by taking buildlets out of a pool of connected, dedicated machines. The buildlet can run in either listen mode (as on GCE and GKE) or in reverse mode. In reverse mode, the buildlet connects out to https://farmer.golang.org/ and registers itself with the coordinator. The TCP connection is then logically reversed (using revdial and when the coordinator needs to do a build, it makes HTTP requests to the coordinator over the already-open TCP connection.

    These three pools can be viewed at the coordinator's http://farmer.golang.org/#pools

  • The env/ directory describes build environments. It contains scripts to create VM images, Dockerfiles to create Kubernetes containers, and instructions and tools for dedicated machines.

  • maintner in maintner/ is a library for slurping all of Go's GitHub and Gerrit state into memory. The daemon maintnerd in maintner/maintnerd/ runs on GKE and serves https://maintner.golang.org/. The daemon watches GitHub and Gerrit and apps to a mutation log whenever it sees new activity. The logs are stored on GCS and served to clients.

  • The godata package in maintner/godata/ provides a trivial API to let anybody write programs against Go's maintner corpus (all of our GitHub and Gerrit history), live up to the second. It takes a few seconds to load into memory and a few hundred MB of RAM after it downloads the mutation log from the network.

  • pubsubhelper in cmd/pubsubhelper/ is a dependency of maintnerd. It runs on GKE, is available at https://pubsubhelper.golang.org/, and runs an HTTP server to receive Webhook updates from GitHub on new activity and an SMTP server to receive new activity emails from Gerrit. It then is a pubsub system for maintnerd to subscribe to.

  • The gitmirror server in cmd/gitmirror/ mirrors Gerrit to GitHub, and also serves a mirror of the Gerrit code to the coordinator for builds, so we don't overwhelm Gerrit and blow our quota.

  • The Go gopherbot bot logic runs on GKE. The code is in cmd/gopherbot. It depends on maintner via the godata package.

  • The developer dashboard at https://dev.golang.org/ runs on GKE. Its code is in devapp/. It also depends on maintner via the godata package.

  • cmd/retrybuilds: a Go client program to delete build results from the dashboard

Adding a Go Builder

If you wish to run a Go builder, please email golang-dev@googlegroups.com first. There is documentation at https://golang.org/wiki/DashboardBuilders, but depending on the type of builder, we may want to run it ourselves, after you prepare an environment description (resulting in a VM image) of it. See the env directory.