feat: Stage 4 — fail2ban connection and server status

This commit is contained in:
2026-02-28 21:48:03 +01:00
parent a41a99dad4
commit 60683da3ca
13 changed files with 1085 additions and 18 deletions

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@@ -33,7 +33,8 @@ from starlette.middleware.base import BaseHTTPMiddleware
from app.config import Settings, get_settings
from app.db import init_db
from app.routers import auth, health, setup
from app.routers import auth, dashboard, health, setup
from app.tasks import health_check
# ---------------------------------------------------------------------------
# Ensure the bundled fail2ban package is importable from fail2ban-master/
@@ -114,6 +115,9 @@ async def _lifespan(app: FastAPI) -> AsyncGenerator[None, None]:
scheduler.start()
app.state.scheduler = scheduler
# --- Health-check background probe ---
health_check.register(app)
log.info("bangui_started")
try:
@@ -268,5 +272,6 @@ def create_app(settings: Settings | None = None) -> FastAPI:
app.include_router(health.router)
app.include_router(setup.router)
app.include_router(auth.router)
app.include_router(dashboard.router)
return app

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@@ -0,0 +1,46 @@
"""Dashboard router.
Provides the ``GET /api/dashboard/status`` endpoint that returns the cached
fail2ban server health snapshot. The snapshot is maintained by the
background health-check task and refreshed every 30 seconds.
"""
from __future__ import annotations
from fastapi import APIRouter, Request
from app.dependencies import AuthDep
from app.models.server import ServerStatus, ServerStatusResponse
router: APIRouter = APIRouter(prefix="/api/dashboard", tags=["Dashboard"])
@router.get(
"/status",
response_model=ServerStatusResponse,
summary="Return the cached fail2ban server status",
)
async def get_server_status(
request: Request,
_auth: AuthDep,
) -> ServerStatusResponse:
"""Return the most recent fail2ban health snapshot.
The snapshot is populated by a background task that runs every 30 seconds.
If the task has not yet executed a placeholder ``online=False`` status is
returned so the response is always well-formed.
Args:
request: The incoming request (used to access ``app.state``).
_auth: Validated session — enforces authentication on this endpoint.
Returns:
:class:`~app.models.server.ServerStatusResponse` containing the
current health snapshot.
"""
cached: ServerStatus = getattr(
request.app.state,
"server_status",
ServerStatus(online=False),
)
return ServerStatusResponse(status=cached)

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@@ -0,0 +1,171 @@
"""Health service.
Probes the fail2ban socket to determine whether the daemon is reachable and
collects aggregated server statistics (version, jail count, ban counts).
The probe is intentionally lightweight — it is meant to be called every 30
seconds by the background health-check task, not on every HTTP request.
"""
from __future__ import annotations
from typing import Any
import structlog
from app.models.server import ServerStatus
from app.utils.fail2ban_client import Fail2BanClient, Fail2BanConnectionError, Fail2BanProtocolError
log: structlog.stdlib.BoundLogger = structlog.get_logger()
# ---------------------------------------------------------------------------
# Internal helpers
# ---------------------------------------------------------------------------
_SOCKET_TIMEOUT: float = 5.0
def _ok(response: Any) -> Any:
"""Extract the payload from a fail2ban ``(return_code, data)`` response.
fail2ban wraps every response in a ``(0, data)`` success tuple or
a ``(1, exception)`` error tuple. This helper returns ``data`` for
successful responses or raises :class:`ValueError` for error responses.
Args:
response: Raw value returned by :meth:`~Fail2BanClient.send`.
Returns:
The payload ``data`` portion of the response.
Raises:
ValueError: If the response indicates an error (return code ≠ 0).
"""
try:
code, data = response
except (TypeError, ValueError) as exc:
raise ValueError(f"Unexpected fail2ban response shape: {response!r}") from exc
if code != 0:
raise ValueError(f"fail2ban returned error code {code}: {data!r}")
return data
def _to_dict(pairs: Any) -> dict[str, Any]:
"""Convert a list of ``(key, value)`` pairs to a plain dict.
fail2ban returns structured data as lists of 2-tuples rather than dicts.
This helper converts them safely, ignoring non-pair items.
Args:
pairs: A list of ``(key, value)`` pairs (or any iterable thereof).
Returns:
A :class:`dict` with the keys and values from *pairs*.
"""
if not isinstance(pairs, (list, tuple)):
return {}
result: dict[str, Any] = {}
for item in pairs:
try:
k, v = item
result[str(k)] = v
except (TypeError, ValueError):
pass
return result
# ---------------------------------------------------------------------------
# Public interface
# ---------------------------------------------------------------------------
async def probe(socket_path: str, timeout: float = _SOCKET_TIMEOUT) -> ServerStatus:
"""Probe the fail2ban daemon and return a :class:`~app.models.server.ServerStatus`.
Sends ``ping``, ``version``, ``status``, and per-jail ``status <jail>``
commands. Any socket or protocol error is caught and results in an
``online=False`` status so the dashboard can always return a safe default.
Args:
socket_path: Path to the fail2ban Unix domain socket.
timeout: Per-command socket timeout in seconds.
Returns:
A :class:`~app.models.server.ServerStatus` snapshot. ``online`` is
``True`` when the daemon is reachable, ``False`` otherwise.
"""
client = Fail2BanClient(socket_path=socket_path, timeout=timeout)
try:
# ------------------------------------------------------------------ #
# 1. Connectivity check #
# ------------------------------------------------------------------ #
ping_data = _ok(await client.send(["ping"]))
if ping_data != "pong":
log.warning("fail2ban_unexpected_ping_response", response=ping_data)
return ServerStatus(online=False)
# ------------------------------------------------------------------ #
# 2. Version #
# ------------------------------------------------------------------ #
try:
version: str | None = str(_ok(await client.send(["version"])))
except (ValueError, TypeError):
version = None
# ------------------------------------------------------------------ #
# 3. Global status — jail count and names #
# ------------------------------------------------------------------ #
status_data = _to_dict(_ok(await client.send(["status"])))
active_jails: int = int(status_data.get("Number of jail", 0) or 0)
jail_list_raw: str = str(status_data.get("Jail list", "") or "").strip()
jail_names: list[str] = (
[j.strip() for j in jail_list_raw.split(",") if j.strip()]
if jail_list_raw
else []
)
# ------------------------------------------------------------------ #
# 4. Per-jail aggregation #
# ------------------------------------------------------------------ #
total_bans: int = 0
total_failures: int = 0
for jail_name in jail_names:
try:
jail_resp = _to_dict(_ok(await client.send(["status", jail_name])))
filter_stats = _to_dict(jail_resp.get("Filter") or [])
action_stats = _to_dict(jail_resp.get("Actions") or [])
total_failures += int(filter_stats.get("Currently failed", 0) or 0)
total_bans += int(action_stats.get("Currently banned", 0) or 0)
except (ValueError, TypeError, KeyError) as exc:
log.warning(
"fail2ban_jail_status_parse_error",
jail=jail_name,
error=str(exc),
)
log.debug(
"fail2ban_probe_ok",
version=version,
active_jails=active_jails,
total_bans=total_bans,
total_failures=total_failures,
)
return ServerStatus(
online=True,
version=version,
active_jails=active_jails,
total_bans=total_bans,
total_failures=total_failures,
)
except (Fail2BanConnectionError, Fail2BanProtocolError) as exc:
log.warning("fail2ban_probe_failed", error=str(exc))
return ServerStatus(online=False)
except ValueError as exc:
log.error("fail2ban_probe_parse_error", error=str(exc))
return ServerStatus(online=False)

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@@ -0,0 +1,79 @@
"""Health-check background task.
Registers an APScheduler job that probes the fail2ban socket every 30 seconds
and stores the result on ``app.state.server_status``. The dashboard endpoint
reads from this cache, keeping HTTP responses fast and the daemon connection
decoupled from user-facing requests.
"""
from __future__ import annotations
from typing import TYPE_CHECKING, Any
import structlog
from app.models.server import ServerStatus
from app.services import health_service
if TYPE_CHECKING: # pragma: no cover
from fastapi import FastAPI
log: structlog.stdlib.BoundLogger = structlog.get_logger()
#: How often the probe fires (seconds).
HEALTH_CHECK_INTERVAL: int = 30
async def _run_probe(app: Any) -> None:
"""Probe fail2ban and cache the result on *app.state*.
This is the APScheduler job callback. It reads ``fail2ban_socket`` from
``app.state.settings``, runs the health probe, and writes the result to
``app.state.server_status``.
Args:
app: The :class:`fastapi.FastAPI` application instance passed by the
scheduler via the ``kwargs`` mechanism.
"""
socket_path: str = app.state.settings.fail2ban_socket
status: ServerStatus = await health_service.probe(socket_path)
app.state.server_status = status
log.debug(
"health_check_complete",
online=status.online,
version=status.version,
active_jails=status.active_jails,
)
def register(app: FastAPI) -> None:
"""Add the health-check job to the application scheduler.
Must be called after the scheduler has been started (i.e., inside the
lifespan handler, after ``scheduler.start()``).
Args:
app: The :class:`fastapi.FastAPI` application instance whose
``app.state.scheduler`` will receive the job.
"""
# Initialise the cache with an offline placeholder so the dashboard
# endpoint is always able to return a valid response even before the
# first probe fires.
app.state.server_status = ServerStatus(online=False)
app.state.scheduler.add_job(
_run_probe,
trigger="interval",
seconds=HEALTH_CHECK_INTERVAL,
kwargs={"app": app},
id="health_check",
replace_existing=True,
# Fire immediately on startup too, so the UI isn't dark for 30 s.
next_run_time=__import__("datetime").datetime.now(
tz=__import__("datetime").timezone.utc
),
)
log.info(
"health_check_scheduled",
interval_seconds=HEALTH_CHECK_INTERVAL,
)

View File

@@ -43,8 +43,8 @@ ignore = ["B008"] # FastAPI uses function calls in default arguments (Depends)
[tool.ruff.lint.per-file-ignores]
# sys.path manipulation before stdlib imports is intentional in test helpers
# pytest evaluates fixture type annotations at runtime, so TC002/TC003 are false-positives
"tests/**" = ["E402", "TC002", "TC003"]
# pytest evaluates fixture type annotations at runtime, so TC001/TC002/TC003 are false-positives
"tests/**" = ["E402", "TC001", "TC002", "TC003"]
"app/routers/**" = ["TC001"] # FastAPI evaluates Depends() type aliases at runtime via get_type_hints()
[tool.ruff.format]

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@@ -0,0 +1,194 @@
"""Tests for the dashboard router (GET /api/dashboard/status)."""
from __future__ import annotations
from pathlib import Path
import aiosqlite
import pytest
from httpx import ASGITransport, AsyncClient
from app.config import Settings
from app.db import init_db
from app.main import create_app
from app.models.server import ServerStatus
# ---------------------------------------------------------------------------
# Fixtures
# ---------------------------------------------------------------------------
_SETUP_PAYLOAD = {
"master_password": "testpassword1",
"database_path": "bangui.db",
"fail2ban_socket": "/var/run/fail2ban/fail2ban.sock",
"timezone": "UTC",
"session_duration_minutes": 60,
}
@pytest.fixture
async def dashboard_client(tmp_path: Path) -> AsyncClient: # type: ignore[misc]
"""Provide an authenticated ``AsyncClient`` with a pre-seeded server status.
Unlike the shared ``client`` fixture this one also exposes access to
``app.state`` via the app instance so we can seed the status cache.
"""
settings = Settings(
database_path=str(tmp_path / "dashboard_test.db"),
fail2ban_socket="/tmp/fake_fail2ban.sock",
session_secret="test-dashboard-secret",
session_duration_minutes=60,
timezone="UTC",
log_level="debug",
)
app = create_app(settings=settings)
db: aiosqlite.Connection = await aiosqlite.connect(settings.database_path)
db.row_factory = aiosqlite.Row
await init_db(db)
app.state.db = db
# Pre-seed a server status so the endpoint has something to return.
app.state.server_status = ServerStatus(
online=True,
version="1.0.2",
active_jails=2,
total_bans=10,
total_failures=5,
)
transport = ASGITransport(app=app)
async with AsyncClient(transport=transport, base_url="http://test") as ac:
# Complete setup so the middleware doesn't redirect.
resp = await ac.post("/api/setup", json=_SETUP_PAYLOAD)
assert resp.status_code == 201
# Login to get a session cookie.
login_resp = await ac.post(
"/api/auth/login",
json={"password": _SETUP_PAYLOAD["master_password"]},
)
assert login_resp.status_code == 200
yield ac
await db.close()
@pytest.fixture
async def offline_dashboard_client(tmp_path: Path) -> AsyncClient: # type: ignore[misc]
"""Like ``dashboard_client`` but with an offline server status."""
settings = Settings(
database_path=str(tmp_path / "dashboard_offline_test.db"),
fail2ban_socket="/tmp/fake_fail2ban.sock",
session_secret="test-dashboard-offline-secret",
session_duration_minutes=60,
timezone="UTC",
log_level="debug",
)
app = create_app(settings=settings)
db: aiosqlite.Connection = await aiosqlite.connect(settings.database_path)
db.row_factory = aiosqlite.Row
await init_db(db)
app.state.db = db
app.state.server_status = ServerStatus(online=False)
transport = ASGITransport(app=app)
async with AsyncClient(transport=transport, base_url="http://test") as ac:
resp = await ac.post("/api/setup", json=_SETUP_PAYLOAD)
assert resp.status_code == 201
login_resp = await ac.post(
"/api/auth/login",
json={"password": _SETUP_PAYLOAD["master_password"]},
)
assert login_resp.status_code == 200
yield ac
await db.close()
# ---------------------------------------------------------------------------
# Tests
# ---------------------------------------------------------------------------
class TestDashboardStatus:
"""GET /api/dashboard/status."""
async def test_returns_200_when_authenticated(
self, dashboard_client: AsyncClient
) -> None:
"""Authenticated request returns HTTP 200."""
response = await dashboard_client.get("/api/dashboard/status")
assert response.status_code == 200
async def test_returns_401_when_unauthenticated(
self, client: AsyncClient
) -> None:
"""Unauthenticated request returns HTTP 401."""
# Complete setup so the middleware allows the request through.
await client.post("/api/setup", json=_SETUP_PAYLOAD)
response = await client.get("/api/dashboard/status")
assert response.status_code == 401
async def test_response_shape_when_online(
self, dashboard_client: AsyncClient
) -> None:
"""Response contains the expected ``status`` object shape."""
response = await dashboard_client.get("/api/dashboard/status")
body = response.json()
assert "status" in body
status = body["status"]
assert "online" in status
assert "version" in status
assert "active_jails" in status
assert "total_bans" in status
assert "total_failures" in status
async def test_cached_values_returned_when_online(
self, dashboard_client: AsyncClient
) -> None:
"""Endpoint returns the exact values from ``app.state.server_status``."""
response = await dashboard_client.get("/api/dashboard/status")
status = response.json()["status"]
assert status["online"] is True
assert status["version"] == "1.0.2"
assert status["active_jails"] == 2
assert status["total_bans"] == 10
assert status["total_failures"] == 5
async def test_offline_status_returned_correctly(
self, offline_dashboard_client: AsyncClient
) -> None:
"""Endpoint returns online=False when the cache holds an offline snapshot."""
response = await offline_dashboard_client.get("/api/dashboard/status")
assert response.status_code == 200
status = response.json()["status"]
assert status["online"] is False
assert status["version"] is None
assert status["active_jails"] == 0
assert status["total_bans"] == 0
assert status["total_failures"] == 0
async def test_returns_offline_when_state_not_initialised(
self, client: AsyncClient
) -> None:
"""Endpoint returns online=False as a safe default if the cache is absent."""
# Setup + login so the endpoint is reachable.
await client.post("/api/setup", json=_SETUP_PAYLOAD)
await client.post(
"/api/auth/login",
json={"password": _SETUP_PAYLOAD["master_password"]},
)
# server_status is not set on app.state in the shared `client` fixture.
response = await client.get("/api/dashboard/status")
assert response.status_code == 200
status = response.json()["status"]
assert status["online"] is False

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@@ -0,0 +1,263 @@
"""Tests for health_service.probe()."""
from __future__ import annotations
from typing import Any
from unittest.mock import AsyncMock, patch
import pytest
from app.models.server import ServerStatus
from app.services import health_service
from app.utils.fail2ban_client import Fail2BanConnectionError, Fail2BanProtocolError
# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------
_SOCKET = "/fake/fail2ban.sock"
def _make_send(responses: dict[str, Any]) -> AsyncMock:
"""Build an ``AsyncMock`` for ``Fail2BanClient.send`` keyed by command[0].
For the ``["status", jail_name]`` command the key is
``"status:<jail_name>"``.
"""
async def _side_effect(command: list[str]) -> Any:
key = f"status:{command[1]}" if len(command) >= 2 and command[0] == "status" else command[0]
if key not in responses:
raise KeyError(f"Unexpected command key {key!r} in mock")
return responses[key]
mock = AsyncMock(side_effect=_side_effect)
return mock
# ---------------------------------------------------------------------------
# Happy path
# ---------------------------------------------------------------------------
class TestProbeOnline:
"""Verify probe() correctly parses a healthy fail2ban response."""
async def test_online_flag_is_true(self) -> None:
"""status.online is True when ping succeeds."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.0.2"),
"status": (0, [("Number of jail", 0), ("Jail list", "")]),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result: ServerStatus = await health_service.probe(_SOCKET)
assert result.online is True
async def test_version_parsed(self) -> None:
"""status.version contains the version string returned by fail2ban."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.1.0"),
"status": (0, [("Number of jail", 0), ("Jail list", "")]),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.version == "1.1.0"
async def test_active_jails_count(self) -> None:
"""status.active_jails reflects the jail count from the status command."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.0.2"),
"status": (0, [("Number of jail", 2), ("Jail list", "sshd, nginx")]),
"status:sshd": (
0,
[
("Filter", [("Currently failed", 3), ("Total failed", 100)]),
("Actions", [("Currently banned", 1), ("Total banned", 50)]),
],
),
"status:nginx": (
0,
[
("Filter", [("Currently failed", 2), ("Total failed", 50)]),
("Actions", [("Currently banned", 0), ("Total banned", 10)]),
],
),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.active_jails == 2
async def test_total_bans_aggregated(self) -> None:
"""status.total_bans sums 'Currently banned' across all jails."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.0.2"),
"status": (0, [("Number of jail", 2), ("Jail list", "sshd, nginx")]),
"status:sshd": (
0,
[
("Filter", [("Currently failed", 3), ("Total failed", 100)]),
("Actions", [("Currently banned", 4), ("Total banned", 50)]),
],
),
"status:nginx": (
0,
[
("Filter", [("Currently failed", 1), ("Total failed", 20)]),
("Actions", [("Currently banned", 2), ("Total banned", 15)]),
],
),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.total_bans == 6 # 4 + 2
async def test_total_failures_aggregated(self) -> None:
"""status.total_failures sums 'Currently failed' across all jails."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.0.2"),
"status": (0, [("Number of jail", 2), ("Jail list", "sshd, nginx")]),
"status:sshd": (
0,
[
("Filter", [("Currently failed", 3), ("Total failed", 100)]),
("Actions", [("Currently banned", 1), ("Total banned", 50)]),
],
),
"status:nginx": (
0,
[
("Filter", [("Currently failed", 2), ("Total failed", 20)]),
("Actions", [("Currently banned", 0), ("Total banned", 10)]),
],
),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.total_failures == 5 # 3 + 2
async def test_empty_jail_list(self) -> None:
"""Probe succeeds with zero jails — no per-jail queries are made."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.0.2"),
"status": (0, [("Number of jail", 0), ("Jail list", "")]),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.online is True
assert result.active_jails == 0
assert result.total_bans == 0
assert result.total_failures == 0
# ---------------------------------------------------------------------------
# Error handling
# ---------------------------------------------------------------------------
class TestProbeOffline:
"""Verify probe() returns online=False when the daemon is unreachable."""
async def test_connection_error_returns_offline(self) -> None:
"""Fail2BanConnectionError → online=False."""
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = AsyncMock(
side_effect=Fail2BanConnectionError("socket not found", _SOCKET)
)
result = await health_service.probe(_SOCKET)
assert result.online is False
assert result.version is None
async def test_protocol_error_returns_offline(self) -> None:
"""Fail2BanProtocolError → online=False."""
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = AsyncMock(
side_effect=Fail2BanProtocolError("bad pickle")
)
result = await health_service.probe(_SOCKET)
assert result.online is False
async def test_bad_ping_response_returns_offline(self) -> None:
"""An unexpected ping response → online=False (defensive guard)."""
send = _make_send({"ping": (0, "NOTPONG")})
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.online is False
async def test_error_code_in_ping_returns_offline(self) -> None:
"""An error return code in the ping response → online=False."""
send = _make_send({"ping": (1, "ERROR")})
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.online is False
async def test_per_jail_error_is_tolerated(self) -> None:
"""A parse error on an individual jail's status does not break the probe."""
send = _make_send(
{
"ping": (0, "pong"),
"version": (0, "1.0.2"),
"status": (0, [("Number of jail", 1), ("Jail list", "sshd")]),
# Return garbage to trigger parse tolerance.
"status:sshd": (0, "INVALID"),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
# The service should still be online even if per-jail parsing fails.
assert result.online is True
assert result.total_bans == 0
assert result.total_failures == 0
@pytest.mark.parametrize("version_return", [(1, "ERROR"), (0, None)])
async def test_version_failure_is_tolerated(self, version_return: tuple[int, Any]) -> None:
"""A failed or null version response does not prevent a successful probe."""
send = _make_send(
{
"ping": (0, "pong"),
"version": version_return,
"status": (0, [("Number of jail", 0), ("Jail list", "")]),
}
)
with patch("app.services.health_service.Fail2BanClient") as mock_client:
mock_client.return_value.send = send
result = await health_service.probe(_SOCKET)
assert result.online is True