fix: expose port 10022, wait for service before ActiveStatus (#11)

* fix: expose port 10022

* chore: prefer return over break

* test: test for open port

src-docs/tmate.py.md

@@ -16,7 +16,7 @@ Configurations and functions to operate tmate-ssh-server.
 
 ---
 
-<a href="../src/tmate.py#L99"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/tmate.py#L102"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ## <kbd>function</kbd> `install_dependencies`
 
@@ -41,7 +41,7 @@ Install dependenciese required to start tmate-ssh-server container.
 
 ---
 
-<a href="../src/tmate.py#L116"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/tmate.py#L119"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ## <kbd>function</kbd> `install_keys`
 
@@ -66,7 +66,7 @@ Install key creation script and generate keys.
 
 ---
 
-<a href="../src/tmate.py#L141"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/tmate.py#L169"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ## <kbd>function</kbd> `start_daemon`
 
@@ -91,7 +91,7 @@ Install unit files and start daemon.
 
 ---
 
-<a href="../src/tmate.py#L192"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/tmate.py#L223"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ## <kbd>function</kbd> `get_fingerprints`
 
@@ -115,7 +115,7 @@ Get fingerprint from generated keys.
 
 ---
 
-<a href="../src/tmate.py#L216"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
+<a href="../src/tmate.py#L247"><img align="right" style="float:right;" src="https://img.shields.io/badge/-source-cccccc?style=flat-square"></a>
 
 ## <kbd>function</kbd> `generate_tmate_conf`
 

src/charm.py

@@ -78,6 +78,7 @@ def _on_install(self, event: ops.InstallEvent) -> None:
             logger.error("Something went wrong initializing keys, %s.", exc)
             raise
 
+        self.unit.open_port("tcp", tmate.PORT)
         self.sshdebug.update_relation_data(host=str(self.state.ip_addr), fingerprints=fingerprints)
         self.unit.status = ops.ActiveStatus()
 

src/tmate.py

@@ -14,7 +14,10 @@
 import subprocess  # nosec
 import textwrap
 import typing
+from datetime import datetime, timedelta
+from functools import partial
 from pathlib import Path
+from time import sleep
 
 import jinja2
 from charms.operator_libs_linux.v0 import apt, passwd
@@ -138,6 +141,31 @@ def install_keys(host_ip: typing.Union[ipaddress.IPv4Address, ipaddress.IPv6Addr
         raise KeyInstallError from exc
 
 
+def _wait_for(
+    func: typing.Callable[[], typing.Any], timeout: int = 300, check_interval: int = 10
+) -> None:
+    """Wait for function execution to become truthy.
+
+    Args:
+        func: A callback function to wait to return a truthy value.
+        timeout: Time in seconds to wait for function result to become truthy.
+        check_interval: Time in seconds to wait between ready checks.
+
+    Raises:
+        TimeoutError: if the callback function did not return a truthy value within timeout.
+    """
+    start_time = now = datetime.now()
+    min_wait_seconds = timedelta(seconds=timeout)
+    while now - start_time < min_wait_seconds:
+        if func():
+            return
+        now = datetime.now()
+        sleep(check_interval)
+    if func():
+        return
+    raise TimeoutError()
+
+
 def start_daemon(address: str) -> None:
     """Install unit files and start daemon.
 
@@ -158,8 +186,11 @@ def start_daemon(address: str) -> None:
     try:
         systemd.daemon_reload()
         systemd.service_start(TMATE_SERVICE_NAME)
+        _wait_for(partial(systemd.service_running, TMATE_SERVICE_NAME), timeout=60 * 10)
     except systemd.SystemdError as exc:
         raise DaemonStartError("Failed to start tmate-ssh-server daemon.") from exc
+    except TimeoutError as exc:
+        raise DaemonStartError("Timed out waiting for tmate service to start.") from exc
 
 
 @dataclasses.dataclass

tests/unit/test_charm.py

@@ -122,7 +122,7 @@ def test__on_install(
     """
     arrange: given a monkeypatched tmate installation function calls.
     act: when _on_install is called.
-    assert: the unit is in active status.
+    assert: the unit is in active status and tmate ssh server port is opened.
     """
     monkeypatch.setattr(tmate, "install_dependencies", MagicMock(spec=tmate.install_dependencies))
     monkeypatch.setattr(tmate, "install_keys", MagicMock(spec=tmate.install_keys))
@@ -132,4 +132,5 @@ def test__on_install(
     mock_event = MagicMock(spec=ops.InstallEvent)
     charm._on_install(mock_event)
 
+    assert ops.Port(protocol="tcp", port=tmate.PORT) in charm.unit.opened_ports()
     assert charm.unit.status.name == "active"

tests/unit/test_tmate.py

@@ -138,9 +138,45 @@ def test_install_keys(monkeypatch: pytest.MonkeyPatch):
     tmate.install_keys(MagicMock())
 
 
+def test__wait_for_timeout_error(monkeypatch: pytest.MonkeyPatch):
+    """
+    arrange: given a mock function that returns Falsy value.
+    act: when _wait_for function is called.
+    assert: TimeoutError is raised.
+    """
+    monkeypatch.setattr(tmate, "sleep", MagicMock(spec=tmate.sleep))  # to speed up testing
+    mock_func = MagicMock(return_value=False)
+
+    with pytest.raises(TimeoutError):
+        tmate._wait_for(mock_func, timeout=2, check_interval=1)
+
+
+@pytest.mark.parametrize(
+    "timeout, interval",
+    [
+        pytest.param(
+            3,
+            1,
+            id="within interval",
+        ),
+        pytest.param(0, 1, id="last check"),
+    ],
+)
+def test__wait_for(monkeypatch: pytest.MonkeyPatch, timeout: int, interval: int):
+    """
+    arrange: given a mock function that returns Truthy value.
+    act: when _wait_for function is called.
+    assert: the function returns without raising an error.
+    """
+    monkeypatch.setattr(tmate, "sleep", MagicMock(spec=tmate.sleep))  # to speed up testing
+    mock_func = MagicMock(return_value=True)
+
+    tmate._wait_for(mock_func, timeout=timeout, check_interval=interval)
+
+
 def test_start_daemon_daemon_reload_error(monkeypatch: pytest.MonkeyPatch):
     """
-    arrange: given a monkeypatched subprocess call that raises CalledProcessError.
+    arrange: given a monkeypatched systemd call that raises SystemdError.
     act: when start_daemon is called.
     assert: DaemonStartError is raised.
     """
@@ -159,9 +195,43 @@ def test_start_daemon_daemon_reload_error(monkeypatch: pytest.MonkeyPatch):
         ),
     )
 
-    with pytest.raises(tmate.DaemonStartError):
+    with pytest.raises(tmate.DaemonStartError) as exc:
+        tmate.start_daemon(address="test")
+
+    assert "Failed to start tmate-ssh-server daemon." in str(exc.value)
+
+
+def test_start_daemon_service_timeout_error(monkeypatch: pytest.MonkeyPatch):
+    """
+    arrange: given a monkeypatched _wait_for systemd service all that raises a timeout error.
+    act: when start_daemon is called.
+    assert: DaemonStartError is raised.
+    """
+    monkeypatch.setattr(tmate, "WORK_DIR", MagicMock(spec=Path))
+    monkeypatch.setattr(tmate, "KEYS_DIR", MagicMock(spec=Path))
+    monkeypatch.setattr(tmate, "CREATE_KEYS_SCRIPT_PATH", MagicMock(spec=Path))
+    monkeypatch.setattr(tmate, "TMATE_SSH_SERVER_SERVICE_PATH", MagicMock(spec=Path))
+    monkeypatch.setattr(
+        tmate.systemd,
+        "daemon_reload",
+        MagicMock(spec=tmate.systemd.daemon_reload),
+    )
+    monkeypatch.setattr(
+        tmate.systemd,
+        "service_start",
+        MagicMock(spec=tmate.systemd.service_start),
+    )
+    monkeypatch.setattr(
+        tmate,
+        "_wait_for",
+        MagicMock(spec=tmate._wait_for, side_effect=TimeoutError),
+    )
+
+    with pytest.raises(tmate.DaemonStartError) as exc:
         tmate.start_daemon(address="test")
 
+    assert "Timed out waiting for tmate service to start." in str(exc.value)
+
 
 def test_start_daemon_service_start_error(monkeypatch: pytest.MonkeyPatch):
     """