RUNTIME UPGRADE: go runtime go1.25.6 → go1.26.1

[campaigner-prod]

Summary: Runtime update — Go 1.25.6 → 1.26.1

What this PR does

Adds toolchain go1.26.1 to go.mod and updates BUILDGOVERSION in the Makefile.

Why golangci-lint had to be upgraded

The original Makefile pinned golangci-lint at v2.8.0, which was built with Go 1.25. When go.mod targets Go 1.26.1, golangci-lint refuses to run:

Error: can't load config: the Go language version (go1.25) used to build
golangci-lint is lower than the targeted Go version (1.26.1)

Upgraded to v2.11.3 (latest, built with Go 1.26) to resolve this.

Changes made to fix lint

golangci-lint v2.11.3 introduced stricter checks that flagged existing code.

QF1012 (staticcheck) — 2 files:

• api/v1beta1/dns_disruption.go, cpuset/cpuset.go: Replaced WriteString(fmt.Sprintf(...)) with fmt.Fprintf(...). Semantically identical — strings.Builder implements io.Writer.

wsl (whitespace linter) — 8 files:

• Added blank lines before statements in cli/chaosli/cmd/context.go, create.go, version.go, cli/handler/main.go, cli/injector/grpc_disruption.go, cpu_stress.go, pod_replacement.go, config/config.go. Pure formatting, no behavioral change.

G118 (gosec) — 1 file — please review:

• watchers/watcher.go line 191: Added //nolint:gosec on context.WithCancel. G118 flags cancel functions that aren't deferred, but here cacheCancelFunc is intentionally stored in w.ctxTuple and called later in watcher.Clean() (line 140). The cancel function must outlive the Start() scope. The nolint is justified but flagging it for your review since it's your codebase.

Makefile comment note

Line 9 has a comment: # change also github actions go build version "GO_VERSION:" if you change the version below. The CI workflow (ci.yml) no longer has a GO_VERSION env var — it uses go-version-file: go.mod instead. The comment appears stale.

Review Checklist

• Review golangci-lint v2.8.0 → v2.11.3 upgrade
• Review the //nolint:gosec in watchers/watcher.go — confirm cancel func lifecycle is correct
• Review QF1012 fmt.Fprintf changes are semantically equivalent
• Stale Makefile comment on line 9 (optional cleanup)

---

🤖 Original PR generated by DataDog Automated Dependency Management System. CI fixes by Claude Code.

[datadog-datadog-prod-us1-2]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

🎯 Code Coverage (details)
• Patch Coverage: 7.14%
• Overall Coverage: 38.49% (-0.41%)

_{This comment will be updated automatically if new data arrives.
🔗 Commit SHA: 820ac26 | Docs | Datadog PR Page | Was this helpful? React with 👍/👎 or give us feedback!}

[SeanMeyer]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-03-25 17:04:54 UTC ℹ️ Start processing command /merge
Use /merge -c to cancel this operation!

---

2026-03-25 17:04:59 UTC ℹ️ MergeQueue: waiting for PR to be ready

This pull request is not mergeable according to GitHub. Common reasons include pending required checks, missing approvals, or merge conflicts — but it could also be blocked by other repository rules or settings.
It will be added to the queue as soon as checks pass and/or get approvals. View in MergeQueue UI.
Note: if you pushed new commits since the last approval, you may need additional approval.
You can remove it from the waiting list with /remove command.

Use /merge -c to cancel this operation!

---

⏳ Processing