Adopt Thruster in front of Puma

[jbirdjavi]

Stacked on #2017 (rails-8.0-upgrade) — depends on #2017; when it merges and its branch is deleted, GitHub auto-retargets this PR to master.

Adopts Thruster in front of Puma per the standing fleet decision (HTTP caching/compression + static serving; the nginx sidecar is subsequently removed in cru-terraform).

Changes

• Gemfile / Gemfile.lock: activate the thruster placeholder (require: false). Lockfile churn is thruster-only (0.1.23). The gem ships a statically linked Go binary — runs on this app's Alpine/musl image unchanged, no base-image or PLATFORMS changes needed.
• bin/thrust: bundler binstub.
• Dockerfile (minimal touches to the deliberately-divergent file):
  • EXPOSE 80 — Thruster's listen port.
  • CMD wrapped: ["./bin/thrust", "bundle", "exec", "puma", "-C", "config/puma.rb"].
  • ENV LOG_REQUESTS="false" — Thruster's per-request Go slog JSON logging defaults ON and shares container stdout with the app's Ougai stream; leaving it on would double log volume into the Ougai-keyed Datadog pipeline and re-log the health checks Rails silences (silence_healthcheck_path). Fleet decision applied to all thruster PRs.
  • nginx VOLUMEs and conf are intentionally untouched — sidecar removal happens later in cru-terraform, only AFTER this image deploys with Thruster.
  • The build-time docs:generate raddocs step is unaffected.
• config/environments/production.rb:
  • public_file_server.enabled = false commented out (restored in the upgrade PR for the nginx interim, with a note pointing here) — the 8.0 default (true) now lets Rails serve public/ behind Thruster. Verified by production boot: enabled = true, ActionDispatch::Static in the middleware stack.
  • Per-app exception to the fleet default: the skeleton's far-future public_file_server.headers (cache-control: public, max-age=1yr) is commented out with a why-note. This app has no digest-stamped assets (no asset pipeline), and public/ serves the canonical-but-mutable XML schema files (public/xmlns/*.xsd — the live schema-namespace URLs, last changed 2026-05-08, CI-validated). A 1-year shared-cache header on those would be harmful, and without digested assets the far-future default has no upside here. This is exactly the "URL-serves genuinely mutable public/ files" case the fleet decision (2026-07-20, which KEEPS the default for asset-pipeline apps) flags for per-app exception.

Verification (local — CI does not run on stacked PRs)

ruby.yml filters pull_request to the default branch, so no checks run against a rails-8.0-upgrade base. Verified locally on this branch:

• CI=true RAILS_ENV=test bundle exec rspec: 670 examples, 0 failures, 3 pending (matches Upgrade Rails 7.2.3.1 → 8.0.5 #2017 / CI baseline)
• standardrb: 0 offenses
• bundle-audit check --update: 0 vulnerabilities, no ignores
• brakeman -A -q --ensure-latest --no-pager: 0 warnings, exit 0
• Thruster boot (test env, HTTP_PORT=8099/TARGET_PORT=3099, curled through the Thruster port):
  • /monitors/lb → 200 (X-Cache: miss — through Thruster's cache layer)
  • /systems → 200 JSON:API payload
  • /xmlns/manifest.xsd → 200 static from public/, no far-future header
  • With LOG_REQUESTS=false: zero request-log lines from Thruster across all requests (without it, one Go slog JSON line per request — confirming the rationale)
  • SIGTERM → Puma graceful stop, Thruster "Server stopped", all processes exited cleanly
• Production-env boot (runner): public_file_server.enabled = true, public_file_server.headers = nil, ActionDispatch::Static present
• After the base merges: rebase onto master + push (or close/reopen) to trigger required checks before merging (retarget alone fires no CI).

Deploy sequencing

1. Upgrade Rails 7.2.3.1 → 8.0.5 #2017 merges → this PR retargets to master, rebase+push for green checks → merge.
2. Image deploys with Thruster listening on 80 (nginx sidecar still in front — no port conflict, bridge networking).
3. cru-terraform PR removes the nginx sidecar (container_port = "80", nginx disabled) — only after step 2 is live.

🤖 Generated with Claude Code

https://claude.ai/code/session_01C9vz7gguLNupgNEFGtjLfX

[stage-branch-merger]

I see you added the "On Staging" label, I'll get this merged to the staging branch!

[stage-branch-merger]

Merge conflict attempting to merge this into staging. Please fix manually.

[jbirdjavi]

Code review

No issues found. Checked for bugs and CLAUDE.md compliance.

🤖 Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}

[knutsenm]

Verified as part of the fleet stack audit:

• Autonag CMD variant — correct, master's CMD already ran puma via the load-bearing config/puma.rb. EXPOSE 80, ENV LOG_REQUESTS="false", executable bin/thrust, thruster-only lockfile churn (0.1.23).
• Commenting out the far-future public_file_server.headers (rather than keeping it) is right for this app: no digested assets exist, and public/xmlns/*.xsd are live, mutable schema-namespace URLs — exactly the mutable-public-files exception. public_file_server.enabled = false commented out per the pattern.
• No CACHE_SIZE=0 — acceptable: the app serves authorized JSON:API but emits no public Cache-Control from controllers (grep-verified), so thruster's shared cache can't store user-scoped responses.

Approving with the standard caveats: zero CI has run on this stacked leg, and this repo's branch protection is strict: true — after #2017 merges, this needs the rebase+push the body describes before it can merge. Post-sidecar-removal, smoke-test /cable WebSockets through thruster in staging (the proxy chain changes), which also exercises the x86_64-linux thrust binary on the Alpine/musl image in a real environment.

🤖 Review drafted with Claude Code