decomposer: generate deliverable files for Define the service contract and project architecture for the FastAPI endpoint monitoring service.; Implement the typed monitor CRUD API and concurrency-safe in-memory state according to the service design.; Implement secure on-demand endpoint checks with status updates, latency measurement, robust error handling, and redacted structured logs.; Add operational API endpoints and environment-driven runtime configuration to the monitoring service.; Create automated tests for the monitoring service.; Package the service with Docker and developer documentation.; Validate the complete project.

tests/test_checker.py

@@ -1,92 +1,71 @@
-import json
 import logging
 
 import httpx
 import pytest
-from fastapi.testclient import TestClient
 
-from app.checker import EndpointChecker
+from endpoint_monitor.checker import EndpointChecker, TargetBlockedError, validate_target
-from app.config import Settings
+from endpoint_monitor.logging import JsonFormatter, redact_url
-from app.logging import JsonFormatter
-from app.main import app
-from app.models import State
-from app.security import DestinationRejected, redacted_url
 
 
 async def public_resolver(host: str, port: int) -> list[str]:
     return ["93.184.216.34"]
 
 
-async def private_resolver(host: str, port: int) -> list[str]:
+@pytest.mark.parametrize("address", ["127.0.0.1", "10.0.0.1", "169.254.169.254", "::1", "fc00::1"])
-    return ["127.0.0.1"]
+async def test_dns_answers_block_non_public(address):
+    async def resolver(host: str, port: int) -> list[str]:
+        return [address]
+
+    with pytest.raises(TargetBlockedError, match="non-public"):
+        await validate_target("http://attacker.example/path", resolver)
 
 
-@pytest.mark.asyncio
+async def test_any_unsafe_dns_answer_blocks_target():
-async def test_success_down_and_transport_error() -> None:
+    async def resolver(host: str, port: int) -> list[str]:
-    async def handler(request: httpx.Request) -> httpx.Response:
+        return ["93.184.216.34", "127.0.0.1"]
-        if request.url.path == "/ok":
-            return httpx.Response(204)
-        if request.url.path == "/down":
-            return httpx.Response(503)
-        raise httpx.ConnectError("secret host detail", request=request)
 
-    worker = EndpointChecker(Settings(), public_resolver, httpx.MockTransport(handler))
+    with pytest.raises(TargetBlockedError):
-    assert (await worker.check("1", "https://example.com/ok?token=x")).state is State.UP
+        await validate_target("https://mixed.example", resolver)
-    assert (await worker.check("1", "https://example.com/down")).state is State.DOWN
-    failed = await worker.check("1", "https://example.com/fail")
-    assert failed.state is State.ERROR
-    assert failed.error == "outbound request failed: ConnectError"
 
 
-@pytest.mark.asyncio
+async def test_redirect_hop_is_resolved_and_blocked():
-async def test_private_dns_and_private_redirect_are_blocked() -> None:
+    seen = []
-    worker = EndpointChecker(Settings(), private_resolver, httpx.MockTransport(lambda r: httpx.Response(200)))
-    with pytest.raises(DestinationRejected):
-        await worker.check("1", "http://example.com")
 
-    calls = 0
+    async def resolver(host: str, port: int) -> list[str]:
+        seen.append(host)
+        return ["127.0.0.1"] if host == "internal.example" else ["93.184.216.34"]
 
-    async def changing_resolver(host: str, port: int) -> list[str]:
+    def handler(request: httpx.Request) -> httpx.Response:
-        return ["127.0.0.1"] if host == "internal.test" else ["93.184.216.34"]
+        return httpx.Response(302, headers={"location": "http://internal.example/admin"})
 
-    async def redirect(request: httpx.Request) -> httpx.Response:
+    checker = EndpointChecker(1, 3, resolver, httpx.MockTransport(handler))
-        nonlocal calls
+    with pytest.raises(TargetBlockedError):
-        calls += 1
+        await checker.check("https://public.example/start", "id")
-        return httpx.Response(302, headers={"location": "http://internal.test/admin"})
+    assert seen == ["public.example", "internal.example"]
-
-    worker = EndpointChecker(Settings(), changing_resolver, httpx.MockTransport(redirect))
-    with pytest.raises(DestinationRejected):
-        await worker.check("1", "https://example.com/start")
-    assert calls == 1
 
 
-def test_api_check_updates_status_and_rejection(client: TestClient) -> None:
+async def test_success_latency_status_and_redaction(caplog):
-    created = client.post(
+    def handler(request: httpx.Request) -> httpx.Response:
-        "/v1/monitors", json={"name": "site", "url": "https://example.com/ok"}
+        return httpx.Response(503)
-    ).json()
-    app.state.checker = EndpointChecker(
-        Settings(), public_resolver, httpx.MockTransport(lambda r: httpx.Response(200))
-    )
-    response = client.post(f"/v1/monitors/{created['id']}/check")
-    assert response.status_code == 200
-    assert response.json()["state"] == "up"
-    assert client.get(f"/v1/monitors/{created['id']}/status").json()["status_code"] == 200
 
-    app.state.checker = EndpointChecker(
+    checker = EndpointChecker(1, 1, public_resolver, httpx.MockTransport(handler))
-        Settings(), private_resolver, httpx.MockTransport(lambda r: httpx.Response(200))
+    with caplog.at_level(logging.INFO):
-    )
+        result = await checker.check("https://example.com/path?token=supersecret#fragment", "abc")
-    response = client.post(f"/v1/monitors/{created['id']}/check")
+    assert result.status.value == "down"
-    assert response.status_code == 400
+    assert result.http_status == 503
-    assert client.get(f"/v1/monitors/{created['id']}/status").json()["state"] == "error"
+    assert result.latency_ms >= 0
+    assert result.final_url == "https://example.com/path"
+    assert "supersecret" not in caplog.text
+    assert "fragment" not in caplog.text
 
 
-def test_url_and_json_log_redaction() -> None:
+def test_redact_url_removes_credentials_query_fragment():
-    safe = redacted_url("https://user:pass@example.com/a?token=secret#fragment")
+    assert redact_url("https://user:pass@example.com:8443/a?q=secret#x") == "https://example.com:8443/a"
-    assert safe == "https://example.com/a?<redacted>"
+
-    record = logging.LogRecord("x", logging.INFO, "", 0, "done", (), None)
+
-    record.url = safe
+def test_json_formatter_is_structured_and_does_not_add_message_secrets():
-    payload = json.loads(JsonFormatter().format(record))
+    record = logging.LogRecord("x", logging.INFO, __file__, 1, "event", (), None)
-    serialized = json.dumps(payload)
+    record.url = redact_url("https://example.com/?api_key=secret")
-    assert "secret" not in serialized
+    rendered = JsonFormatter().format(record)
-    assert "pass" not in serialized
+    assert '"event":"event"' in rendered
-    assert payload["url"].endswith("?<redacted>")
+    assert "secret" not in rendered