Added Unix socket support for the Prometheus metrics server.

tests/test_cli.py

@@ -33,6 +33,7 @@ from crabstero.__main__ import (
     _watchdog_interval,
     _watchdog_loop,
 )
+from crabstero.metrics import TcpMetricsAddress, UnixMetricsAddress
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Coroutine
@@ -141,7 +142,7 @@ class TestParseArgs:
     def test_listen_metrics_parses_address(self) -> None:
         """--listen-metrics HOST:PORT sets listen_metrics to (host, port)."""
         args = _parse_args(["--token", "test", "--listen-metrics", "127.0.0.1:9090"])
-        assert args.listen_metrics == ("127.0.0.1", 9090)
+        assert args.listen_metrics == TcpMetricsAddress("127.0.0.1", 9090)
 
     def test_listen_metrics_default_none(self, monkeypatch: pytest.MonkeyPatch) -> None:
         """Omitting --listen-metrics defaults to None."""
@@ -152,13 +153,29 @@ class TestParseArgs:
     def test_listen_metrics_ipv6(self) -> None:
         """--listen-metrics [::1]:PORT parses IPv6 address correctly."""
         args = _parse_args(["--token", "test", "--listen-metrics", "[::1]:9090"])
-        assert args.listen_metrics == ("[::1]", 9090)
+        assert args.listen_metrics == TcpMetricsAddress("[::1]", 9090)
 
     def test_listen_metrics_from_env(self, monkeypatch: pytest.MonkeyPatch) -> None:
         """LISTEN_METRICS env var is used when --listen-metrics is omitted."""
         monkeypatch.setenv("LISTEN_METRICS", "127.0.0.1:8080")
         args = _parse_args(["--token", "test"])
-        assert args.listen_metrics == ("127.0.0.1", 8080)
+        assert args.listen_metrics == TcpMetricsAddress("127.0.0.1", 8080)
+
+    def test_listen_metrics_unix_socket(self) -> None:
+        """--listen-metrics unix:/path sets listen_metrics to a Unix socket."""
+        args = _parse_args(
+            ["--token", "test", "--listen-metrics", "unix:/run/crabstero.sock"],
+        )
+        assert args.listen_metrics == UnixMetricsAddress("/run/crabstero.sock")
+
+    def test_listen_metrics_unix_socket_from_env(
+        self,
+        monkeypatch: pytest.MonkeyPatch,
+    ) -> None:
+        """LISTEN_METRICS can enable metrics on a Unix socket."""
+        monkeypatch.setenv("LISTEN_METRICS", "unix:/run/crabstero.sock")
+        args = _parse_args(["--token", "test"])
+        assert args.listen_metrics == UnixMetricsAddress("/run/crabstero.sock")
 
     def test_listen_metrics_invalid_format(self) -> None:
         """--listen-metrics with no colon raises SystemExit."""
@@ -170,6 +187,11 @@ class TestParseArgs:
         with pytest.raises(SystemExit):
             _parse_args(["--token", "test", "--listen-metrics", "127.0.0.1:abc"])
 
+    def test_listen_metrics_empty_unix_socket_path(self) -> None:
+        """--listen-metrics unix: with no path raises SystemExit."""
+        with pytest.raises(SystemExit):
+            _parse_args(["--token", "test", "--listen-metrics", "unix:"])
+
     def test_missing_token_exits(self, monkeypatch: pytest.MonkeyPatch) -> None:
         """Missing token causes SystemExit."""
         monkeypatch.delenv("TOKEN", raising=False)