feat: add tables for PGCoordinator v2 (#10442)

Adds tables for a simplified PG Coordinator that only considers Peers and Tunnels, rather than agent/client distinctions we have today.

coderd/database/migrations/000168_pg_coord_tailnet_v2_api.down.sql

@@ -0,0 +1,14 @@
+BEGIN;
+
+DROP TRIGGER IF EXISTS tailnet_notify_tunnel_change ON tailnet_tunnels;
+DROP FUNCTION IF EXISTS tailnet_notify_tunnel_change;
+DROP TABLE IF EXISTS tailnet_tunnels;
+
+DROP TRIGGER IF EXISTS tailnet_notify_peer_change ON tailnet_peers;
+DROP FUNCTION IF EXISTS tailnet_notify_peer_change;
+DROP INDEX IF EXISTS idx_tailnet_peers_coordinator;
+DROP TABLE IF EXISTS tailnet_peers;
+
+DROP TYPE IF EXISTS tailnet_status;
+
+COMMIT;

coderd/database/migrations/000168_pg_coord_tailnet_v2_api.up.sql

@@ -0,0 +1,72 @@
+BEGIN;
+
+CREATE TYPE tailnet_status AS ENUM (
+	'ok',
+	'lost'
+);
+
+CREATE TABLE tailnet_peers (
+	id uuid NOT NULL,
+	coordinator_id uuid NOT NULL,
+	updated_at timestamp with time zone NOT NULL,
+	node bytea NOT NULL,
+	status tailnet_status DEFAULT 'ok'::tailnet_status NOT NULL,
+	PRIMARY KEY (id, coordinator_id),
+	FOREIGN KEY (coordinator_id) REFERENCES tailnet_coordinators(id) ON DELETE CASCADE
+);
+
+-- For shutting down / GC a coordinator
+CREATE INDEX idx_tailnet_peers_coordinator ON tailnet_peers (coordinator_id);
+
+-- Any time tailnet_peers table changes, send an update with the affected peer ID.
+CREATE FUNCTION tailnet_notify_peer_change() RETURNS trigger
+	LANGUAGE plpgsql
+AS $$
+BEGIN
+	IF (OLD IS NOT NULL) THEN
+		PERFORM pg_notify('tailnet_peer_update', OLD.id::text);
+		RETURN NULL;
+	END IF;
+	IF (NEW IS NOT NULL) THEN
+		PERFORM pg_notify('tailnet_peer_update', NEW.id::text);
+		RETURN NULL;
+	END IF;
+END;
+$$;
+
+CREATE TRIGGER tailnet_notify_peer_change
+	AFTER INSERT OR UPDATE OR DELETE ON tailnet_peers
+	FOR EACH ROW
+EXECUTE PROCEDURE tailnet_notify_peer_change();
+
+CREATE TABLE tailnet_tunnels (
+	coordinator_id uuid NOT NULL,
+	-- we don't keep foreign keys for src_id and dst_id because the coordinator doesn't
+	-- strictly order creating the peers and creating the tunnels
+	src_id uuid NOT NULL,
+	dst_id uuid NOT NULL,
+	updated_at timestamp with time zone NOT NULL,
+	PRIMARY KEY (coordinator_id, src_id, dst_id),
+	FOREIGN KEY (coordinator_id)  REFERENCES tailnet_coordinators (id) ON DELETE CASCADE
+);
+
+CREATE FUNCTION tailnet_notify_tunnel_change() RETURNS trigger
+	LANGUAGE plpgsql
+AS $$
+BEGIN
+	IF (NEW IS NOT NULL) THEN
+		PERFORM pg_notify('tailnet_tunnel_update', NEW.src_id || ',' || NEW.dst_id);
+		RETURN NULL;
+	ELSIF (OLD IS NOT NULL) THEN
+		PERFORM pg_notify('tailnet_tunnel_update', OLD.src_id || ',' || OLD.dst_id);
+		RETURN NULL;
+	END IF;
+END;
+$$;
+
+CREATE TRIGGER tailnet_notify_tunnel_change
+	AFTER INSERT OR UPDATE OR DELETE ON tailnet_tunnels
+	FOR EACH ROW
+EXECUTE PROCEDURE tailnet_notify_tunnel_change();
+
+COMMIT;

coderd/database/migrations/testdata/fixtures/000168_pg_coord_tailnet_v2_api.up.sql

@@ -0,0 +1,18 @@
+INSERT INTO tailnet_peers
+	(id, coordinator_id, updated_at, node, status)
+VALUES (
+	'c0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
+	'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
+	'2023-06-15 10:23:54+00',
+	'a fake protobuf byte string',
+	'ok'
+);
+
+INSERT INTO tailnet_tunnels
+	(coordinator_id, src_id, dst_id, updated_at)
+VALUES (
+	'a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
+	'c0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
+	'b0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11',
+	'2023-06-15 10:23:54+00'
+);