# automc extensions

Soft fork of `itzg/mc-router` that adds Postgres-driven route management and an HTTP waker, without touching upstream behavior by default.

The `internal/automc` package is opt-in via env vars: with `AUTOMC_DSN` unset, the binary behaves exactly like upstream.

## Environment variables

| Var | Required | Purpose |
|---|---|---|
| `AUTOMC_DSN` | yes (to enable) | Postgres DSN, e.g. `postgres://user:pass@host:5432/automc?sslmode=disable`. When unset, automc is a no-op. |
| `AUTOMC_WAKER_URL` | no | Base URL of the waker control plane (server-manager). When set, stopped backends are auto-started on login. |
| `AUTOMC_WAKER_TOKEN` | no | Sent as `X-API-Key` header on every waker request. |

Recommended companion upstream flags:

- `--use-asleep-motd` / `--use-loading-motd` — supplies friendly MOTD to clients during the wake window. Already implemented upstream; automc does not duplicate this.

## Postgres schema

Apply this once to the database referenced by `AUTOMC_DSN`. mc-router only reads; the trigger is what tells it to re-read.

```sql
CREATE TABLE IF NOT EXISTS servers (
    name    TEXT PRIMARY KEY,
    domain  TEXT NOT NULL,
    address TEXT NOT NULL,
    state   TEXT NOT NULL DEFAULT 'stopped',
    UNIQUE(domain)
);

CREATE OR REPLACE FUNCTION automc_notify_routes_changed() RETURNS trigger AS $$
BEGIN
    PERFORM pg_notify('automc_routes_changed', '');
    RETURN NULL;
END;
$$ LANGUAGE plpgsql;

DROP TRIGGER IF EXISTS automc_servers_route_notify ON servers;
CREATE TRIGGER automc_servers_route_notify
    AFTER INSERT OR UPDATE OF domain, address, state OR DELETE ON servers
    FOR EACH ROW EXECUTE FUNCTION automc_notify_routes_changed();
```

The trigger fires on every mutation to a route-relevant column. mc-router holds a persistent `LISTEN automc_routes_changed` and re-runs `SELECT name, domain, address FROM servers WHERE domain != '' AND address != ''`, diffing against its in-memory map. Adds/removes/changes call `server.Routes.CreateMapping` and `DeleteMapping` directly — no file I/O.

State column is not read by mc-router; it exists to drive the trigger and for the waker's own ready-check.

## Waker contract

When `AUTOMC_WAKER_URL` is set, every route is registered with a `WakerFunc` that the upstream connector calls only when a client tries to LOGIN (not on status pings — those are answered locally via `--use-asleep-motd`).

The waker:

1. `POST {AUTOMC_WAKER_URL}/servers/{name}/start` — fire-and-forget start signal. `409 Conflict` is treated as success (already starting).
2. Polls `GET {AUTOMC_WAKER_URL}/servers/{name}` every 2 s, expecting JSON `{"state":"running","address":"host:port"}`.
3. Returns the polled `address` once `state == "running"`, or errors after 90 s.

The polled address overrides the route's static address for that connection only — useful when the backend's IP is allocated lazily.

## Upstream sync

```
make sync-upstream
```

Fetches `upstream/main`, rebases the `automc` branch onto it, builds, and runs the automc tests. The patch surface is intentionally tiny so rebase conflicts are rare:

```
cmd/mc-router/main.go  — 1 import line + 4-line Wire call
internal/automc/       — new directory; no upstream conflicts possible
docs/AUTOMC.md         — new doc; no upstream conflicts
Makefile               — appended targets only
go.mod / go.sum        — pgx dep added; mergeable
```

If upstream renames `server.Routes.CreateMapping` or changes its signature, only `pgsync.go:apply` needs adjustment.

## Verification

```
go build ./...
go test ./internal/automc/...
go vet ./...
```