[nomad-step-3] S3-fix-6 — woodpecker-agent can't reach server gRPC at localhost:9000 (port bound to LXC IP) #964

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opened 2026-04-17 14:40:16 +00:00 by dev-bot · 0 comments

dev-bot commented

2026-04-17 14:40:16 +00:00

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Step 4 verification: woodpecker-agent crashes with connection refused localhost:9000.

Root cause

WP agent jobspec has WOODPECKER_SERVER=localhost:9000. Agent runs network_mode=host. But WP server's gRPC port 9000 is mapped via Docker port binding to the LXC's eth0 IP (10.10.10.x:9000), not 127.0.0.1:9000.

Nomad's Docker driver binds ports to the allocation's IP, not localhost, unless the jobspec explicitly requests 0.0.0.0.

Fix

Two options:

A (preferred): In nomad/jobs/woodpecker-agent.hcl, change WOODPECKER_SERVER to use Nomad service discovery or the LXC hostname:

WOODPECKER_SERVER={{ env "attr.unique.network.ip-address" }}:9000

Or hardcode the bridge/host IP that both containers share.

B: In nomad/jobs/woodpecker-server.hcl, bind gRPC to 0.0.0.0:9000 by adding address_mode = "host" to the port stanza, which makes it listen on all interfaces including localhost.

Acceptance criteria

WP agent connects to WP server gRPC without connection refused.
Agent appears in WP UI under "Agents".
nomad alloc logs woodpecker-agent shows "Starting Woodpecker agent" without connection errors.

Labels / meta

backlog + bug-report.

Step 4 verification: woodpecker-agent crashes with `connection refused localhost:9000`. ## Root cause WP agent jobspec has `WOODPECKER_SERVER=localhost:9000`. Agent runs `network_mode=host`. But WP server's gRPC port 9000 is mapped via Docker port binding to the LXC's eth0 IP (`10.10.10.x:9000`), not `127.0.0.1:9000`. Nomad's Docker driver binds ports to the allocation's IP, not localhost, unless the jobspec explicitly requests `0.0.0.0`. ## Fix Two options: **A** (preferred): In `nomad/jobs/woodpecker-agent.hcl`, change `WOODPECKER_SERVER` to use Nomad service discovery or the LXC hostname: ``` WOODPECKER_SERVER={{ env "attr.unique.network.ip-address" }}:9000 ``` Or hardcode the bridge/host IP that both containers share. **B**: In `nomad/jobs/woodpecker-server.hcl`, bind gRPC to `0.0.0.0:9000` by adding `address_mode = "host"` to the port stanza, which makes it listen on all interfaces including localhost. ## Acceptance criteria - WP agent connects to WP server gRPC without `connection refused`. - Agent appears in WP UI under "Agents". - `nomad alloc logs woodpecker-agent` shows `"Starting Woodpecker agent"` without connection errors. ## Labels / meta - `backlog` + `bug-report`.