Bind puma to 0.0.0.0 and allow Tailscale host #5

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opened 2026-05-19 11:12:59 +00:00 by ldraney · 0 comments

ldraney commented

2026-05-19 11:12:59 +00:00

Owner

Type

Bug

Lineage

Standalone — discovered deploying mdview behind Tailscale Funnel tunnel.

Repo

ldraney/mdview

What Broke

Two issues prevented tunnel access: (1) Puma bound to 127.0.0.1, unreachable from the cluster nginx proxy over Tailscale. (2) Rails host authorization returned 403 for mdview.tail5b443a.ts.net requests.

Repro Steps

Start mdview with mdview README.md
ss -tlnp | grep 3137 shows 127.0.0.1:3137
Cluster nginx proxy cannot reach puma — 502
After fixing binding, curl https://mdview.tail5b443a.ts.net/ returns 403 (Rails host check)

Expected Behavior

Puma binds to 0.0.0.0:3137 and Rails accepts requests from the Tailscale Funnel domain.

Environment

Local: archbox (Rails development mode)
Tunnel: mdview namespace on prod cluster
Related alerts: none

Acceptance Criteria

Puma binds to 0.0.0.0:3137
Rails accepts *.tail5b443a.ts.net host header
mdview.tail5b443a.ts.net returns 200 when puma is up

mdview — the markdown viewer project

### Type Bug ### Lineage Standalone — discovered deploying mdview behind Tailscale Funnel tunnel. ### Repo `ldraney/mdview` ### What Broke Two issues prevented tunnel access: (1) Puma bound to `127.0.0.1`, unreachable from the cluster nginx proxy over Tailscale. (2) Rails host authorization returned 403 for `mdview.tail5b443a.ts.net` requests. ### Repro Steps 1. Start mdview with `mdview README.md` 2. `ss -tlnp | grep 3137` shows `127.0.0.1:3137` 3. Cluster nginx proxy cannot reach puma — 502 4. After fixing binding, `curl https://mdview.tail5b443a.ts.net/` returns 403 (Rails host check) ### Expected Behavior Puma binds to `0.0.0.0:3137` and Rails accepts requests from the Tailscale Funnel domain. ### Environment - Local: archbox (Rails development mode) - Tunnel: mdview namespace on prod cluster - Related alerts: none ### Acceptance Criteria - [ ] Puma binds to `0.0.0.0:3137` - [ ] Rails accepts `*.tail5b443a.ts.net` host header - [ ] `mdview.tail5b443a.ts.net` returns 200 when puma is up ### Related - `mdview` — the markdown viewer project