thermograph/infra/deploy/swarm/README.md

# 3-node Docker Swarm (prod + beta + desktop), for hosting Forgejo

This Swarm cluster's only job is to run Forgejo (`deploy/forgejo/`) — it does
**not** orchestrate the Thermograph app itself, which stays on the
Terraform-managed `docker compose` deploys on prod/beta independently (see
`terraform/README.md`). Keeping those separate means nothing here can strand
or interfere with the app's already-working, single-writer Postgres/TimescaleDB
deploys.

This is the canonical topology from
`thermograph-docs/runbooks/implementation-handoff.md` (Track B steps 2-3) — three nodes,
not two. An earlier revision of this doc/scripts covered just prod+beta;
the desktop (this LAN dev machine) joins too.

**Nodes:**
- **manager** — prod, the new 48 GB / 12-core box (more headroom).
- **worker** — beta, the old VPS (`75.119.132.91`).
- **worker** — desktop, this LAN dev machine (also runs the Forgejo Actions
  runner as a plain systemd service — see `deploy/forgejo/README.md` — not as
  a Swarm-scheduled container).

One manager, not more: Raft needs 3 nodes for real quorum-based HA, and this
cluster only has 3 nodes total, so making even one more of them a manager
would still fall short of real HA while adding split-brain risk. If the
manager (prod) goes down, the workers keep running whatever was already
scheduled on them (Forgejo, pinned to beta) but the cluster can't reschedule
anything until prod's back — acceptable for a small cluster whose only job is
CI/CD.

## Order of operations

1. **Agent access first** (`deploy/provision-agent-access.sh`) on prod and
   beta — everything below on those two boxes is run through that access. The
   desktop is wherever you're already working from; no separate access step
   needed there.
2. **WireGuard mesh** (`setup-wireguard.sh <my_wg_ip> <peers_file>`) — run on
   **all three** nodes. See the script's header for the peer-list format and
   the two-pass key-exchange dance (pubkeys aren't known until every node has
   run it once). Verify with `ping <peer_wg_ip>` to each of the other two
   before continuing.
3. **Swarm init** (`init-swarm.sh <manager_wg_ip>`) on the manager (prod) only.
4. **Swarm join** (`join-swarm.sh <manager_wg_ip> <token>`) on **each** of the
   two workers (beta, desktop) — same token for both.
5. **Firewall lockdown** (`firewall-swarm.sh`) on **all three** nodes — closes
   2377/7946/4789 to everything except the WireGuard interface. Do this
   *after* joining is confirmed working on all three, not before (locking the
   ports first would make the join itself fail).
6. **Label beta** (`label-forge-node.sh <beta-node-name>`) on the manager —
   `docker node ls` shows each node's name/ID. Only beta gets `role=forge`;
   the desktop and prod don't need a Swarm label for anything in this setup.
7. Deploy Forgejo: see `deploy/forgejo/README.md`.
8. Register the Actions runner **on the desktop** (not through Swarm):
   `deploy/forgejo/register-lan-runner.sh`.

## Why WireGuard instead of relying on Swarm's built-in TLS alone

Swarm's control plane (port 2377) is TLS-encrypted and mutually authenticated
by default. Its overlay data plane (VXLAN, port 4789) is **not** encrypted by
default, and Docker's own guidance is that port must never face the public
internet — these nodes are on different networks (two separate providers'
public IPs, plus a home/LAN connection for the desktop), not one private LAN,
so the tunnel is the network boundary the Swarm ports advertise into, rather
than trusting the public internet (or the desktop's home network) directly.

## Verifying

```bash
# On the manager:
docker node ls                      # all three nodes Ready
docker node inspect <beta-node> --format '{{.Spec.Labels}}'   # role:forge

# From a FOURTH machine outside the mesh entirely, confirm the Swarm ports
# are NOT reachable on either VPS's public IP (the desktop has no public IP
# to check this way):
nc -zv -w2 <prod_or_beta_public_ip> 2377   # should fail/timeout
nc -zvu -w2 <prod_or_beta_public_ip> 4789  # should fail/timeout
```

## Adding a node label back out (undo)

```bash
docker node update --label-rm role <beta-node>
```