build: move dev tools into per-tool Go modules

[arthurschreiber]

Description

This moves our dev tools out of the main module graph so tool dependencies can't influence application dependency resolution (and vice versa):

• gofumpt, goimports, gotestsum, goyacc, golangci-lint each get their own pinned module under tools/, invoked via go tool -modfile=.... Everything stays at exactly the version we use today, so this is pure plumbing — no reformatting or lint fallout.
• The protoc plugins (protoc-gen-go, protoc-gen-go-grpc, protoc-gen-go-vtproto) become tool directives in the main go.mod. The first and last are packages inside the protobuf/vtprotobuf runtime modules, so the generated code can no longer drift from the runtime libraries — same require line. The install_protoc-gen-go make target is gone; make proto resolves the plugin binaries straight out of the Go build cache with go tool -n.

Some inconsistencies this cleans up along the way:

• goimports was installed ad-hoc in four CI workflows (one of them pinned differently from the others) and never had a go.sum-verified pin. Now it does, and the install steps are deleted — go/tools/codegen resolves the formatters via their modfiles instead of $PATH.
• protoc-gen-go-grpc sat in the main go.mod at v1.6.2 (kept alive by tools/tools.go, dutifully bumped by dependabot) while the Makefile hardcoded @v1.2.0. It's now an honest require at v1.2.0 with a dependabot ignore, since bumping it changes the generated API and needs to be a conscious decision.
• The lint-fmt git hook no longer version-compares a $PATH-installed golangci-lint against build.env — go tool builds the pinned version on demand. That also fixes the hook accepting a newer local lint version than CI uses.

A nice property for git worktrees: all tool resolution is anchored to the current checkout (relative -modfile paths, go env GOMOD in the codegen wrapper, git rev-parse --show-toplevel in the hook), so each worktree uses its own tools/*/go.mod at its own commit — a worktree on an older release branch automatically gets that branch's pinned tool versions. With $PATH-installed tools that was never guaranteed. The module and build caches stay per-user, so a given tool version is still only downloaded and compiled once across all worktrees.

CI changes: the tidy check now covers the tool modules, the go_files filter triggers on tool-module changes, and the Go caches hash tools/**/go.sum too. Dependabot bumps the light tools as a group and golangci-lint in its own PR (lint bumps can change findings).

Verified that proto, sqlparser, sizegen, and vtctldclient regeneration all produce byte-identical output, including make proto from a clean build cache.

Related Issue(s)

N/A

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

N/A — developer tooling and CI only, no runtime changes.

Backporting

I'd like to backport this to release-23.0 and release-24.0, because it's a significant QoL improvement when switching between branches / working on backports.

AI Disclosure

This PR was written primarily by Claude Code — I provided direction and review.

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🤖 Generated with Claude Code

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[Copilot]

Pull request overview

This PR restructures Vitess developer tooling dependencies so they no longer participate in (or get influenced by) the main module’s dependency graph, while keeping tool versions pinned and reproducible across local dev and CI.

Changes:

• Moved several dev tools (gofumpt, goimports, gotestsum, goyacc, golangci-lint) into dedicated tools/<tool>/ Go modules and updated scripts/Make targets to run them via go tool -modfile=....
• Replaced the legacy tools/tools.go “tools” pattern by using tool directives in the root go.mod for protoc plugins, and adjusted make proto to locate plugin binaries via go tool -n.
• Updated CI caching, change detection, tidy checks, and Dependabot configuration to account for the new tool modules.

Reviewed changes

Copilot reviewed 22 out of 28 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tools/unit_test_runner.sh	Runs gotestsum via the pinned tool-module modfile.
tools/e2e_go_test.sh	Runs gotestsum via the pinned tool-module modfile for e2e harness.
tools/check_make_parser.sh	Switches parser regeneration checks to pinned goyacc/goimports/gofumpt tool modules.
misc/git/hooks/lint-fmt	Runs golangci-lint via pinned tool-module modfile instead of $PATH/version checks.
Makefile	Uses pinned tool modules for lint/format; removes install target for protoc plugins and resolves them via go tool -n.
go/vt/vtctl/vtctldclient/Makefile	Formats generated client code via pinned gofumpt modfile.
go/vt/sqlparser/generate.go	Updates go:generate directives to use pinned tool-module modfiles.
go/tools/codegen/goimports.go	Executes goimports/gofumpt via go tool -modfile=... using repo-root resolution.
tools/tools.go	Removes the legacy “tools” build-tag file that pinned tool deps in the main module graph.
tools/gofumpt/go.mod	Adds a dedicated Go module to pin gofumpt as a tool.
tools/gofumpt/go.sum	Checksums for the pinned gofumpt tool module.
tools/goimports/go.mod	Adds a dedicated Go module to pin goimports as a tool.
tools/goimports/go.sum	Checksums for the pinned goimports tool module.
tools/gotestsum/go.mod	Adds a dedicated Go module to pin gotestsum as a tool.
tools/gotestsum/go.sum	Checksums for the pinned gotestsum tool module.
tools/goyacc/go.mod	Adds a dedicated Go module to pin goyacc as a tool.
tools/goyacc/go.sum	Checksums for the pinned goyacc tool module.
tools/golangci-lint/go.mod	Adds a dedicated Go module to pin golangci-lint as a tool.
tools/golangci-lint/go.sum	Checksums for the pinned golangci-lint tool module.
go.mod	Replaces tool pinning approach: removes tool pins for formatting/testing tools; adds tool directives for protoc plugins and pins protoc-gen-go-grpc.
go.sum	Drops now-unneeded tool-related sums from the main module; updates sums for the new root requirements.
build.env	Removes golangci-lint version export since lint version is now pinned by tool module.
.github/workflows/unit_test.yml	Updates Go cache dependency paths; removes ad-hoc goimports install; uses pinned gotestsum modfile.
.github/workflows/static_checks_etc.yml	Expands change filters and cache deps for tool modules; runs go mod tidy across tool modules; derives golangci-lint version from tool module.
.github/workflows/codecov.yml	Updates Go cache dependency paths; removes ad-hoc goimports install.
.github/workflows/check_make_vtadmin_authz_testgen.yml	Updates Go cache dependency paths; removes ad-hoc goimports install.
.github/dependabot.yml	Adds separate update groups for tool modules; ignores protoc-gen-go-grpc auto-bumps.
.github/actions/setup-go/action.yml	Includes tools/**/go.sum in Go cache key hashing to avoid stale caches.

[codecov]

Codecov Report

❌ Patch coverage is 76.92308% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.26%. Comparing base (70c7a72) to head (2c090e9).
⚠️ Report is 311 commits behind head on main.

Files with missing lines	Patch %	Lines
go/tools/codegen/goimports.go	76.92%	3 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (70c7a72) and HEAD (2c090e9). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (70c7a72)	HEAD (2c090e9)
	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #20293       +/-   ##
===========================================
- Coverage   69.67%   56.26%   -13.41%     
===========================================
  Files        1614       46     -1568     
  Lines      216793    14176   -202617     
===========================================
- Hits       151044     7976   -143068     
+ Misses      65749     6200    -59549     

Flag	Coverage Δ
partial	56.26% <76.92%> (?)

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