Add remote autoscaler daemon endpoint support

agent/nix_builder_autoscaler/__main__.py

@@ -218,16 +218,23 @@ def main() -> None:
     reconciler_thread.start()
     metrics_thread.start()
 
-    socket_path = Path(config.server.socket_path)
-    socket_path.parent.mkdir(parents=True, exist_ok=True)
-    if socket_path.exists():
-        socket_path.unlink()
-
-    uvicorn_config = uvicorn.Config(
-        app=app,
-        uds=config.server.socket_path,
-        log_level=config.server.log_level.lower(),
-    )
+    if config.server.listen_port > 0:
+        uvicorn_config = uvicorn.Config(
+            app=app,
+            host=config.server.listen_host,
+            port=config.server.listen_port,
+            log_level=config.server.log_level.lower(),
+        )
+    else:
+        socket_path = Path(config.server.socket_path)
+        socket_path.parent.mkdir(parents=True, exist_ok=True)
+        if socket_path.exists():
+            socket_path.unlink()
+        uvicorn_config = uvicorn.Config(
+            app=app,
+            uds=config.server.socket_path,
+            log_level=config.server.log_level.lower(),
+        )
     server = uvicorn.Server(uvicorn_config)
 
     def _handle_signal(signum: int, _: FrameType | None) -> None:

agent/nix_builder_autoscaler/api.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import hmac
 import logging
 import uuid
 from collections.abc import Callable
@@ -118,6 +119,8 @@ def create_app(
     app.state.runtime = runtime
     app.state.haproxy = haproxy
 
+    auth_token = config.server.auth_token.strip()
+
     @app.middleware("http")
     async def request_id_middleware(request: Request, call_next: Callable) -> Response:
         request.state.request_id = str(uuid.uuid4())
@@ -125,6 +128,25 @@ def create_app(
         response.headers["x-request-id"] = request.state.request_id
         return response
 
+    @app.middleware("http")
+    async def auth_middleware(request: Request, call_next: Callable) -> Response:
+        path = request.url.path
+        if auth_token != "" and (path.startswith("/v1/") or path == "/metrics"):
+            expected = f"Bearer {auth_token}"
+            provided = request.headers.get("authorization", "")
+            if not hmac.compare_digest(provided, expected):
+                request_id = getattr(request.state, "request_id", str(uuid.uuid4()))
+                payload = ErrorResponse(
+                    error=ErrorDetail(
+                        code="unauthorized",
+                        message="Missing or invalid bearer token",
+                        retryable=False,
+                    ),
+                    request_id=request_id,
+                )
+                return JSONResponse(status_code=401, content=payload.model_dump(mode="json"))
+        return await call_next(request)
+
     @app.exception_handler(HTTPException)
     async def http_exception_handler(request: Request, exc: HTTPException) -> JSONResponse:
         detail = exc.detail

agent/nix_builder_autoscaler/config.py

@@ -13,6 +13,9 @@ class ServerConfig:
     """[server] section."""
 
     socket_path: str = "/run/nix-builder-autoscaler/daemon.sock"
+    listen_host: str = "127.0.0.1"
+    listen_port: int = 0
+    auth_token: str = ""
     log_level: str = "info"
     db_path: str = "/var/lib/nix-builder-autoscaler/state.db"
 

agent/nix_builder_autoscaler/tests/test_reservations_api.py

@@ -8,7 +8,7 @@ from typing import Any
 from fastapi.testclient import TestClient
 
 from nix_builder_autoscaler.api import create_app
-from nix_builder_autoscaler.config import AppConfig, CapacityConfig
+from nix_builder_autoscaler.config import AppConfig, CapacityConfig, ServerConfig
 from nix_builder_autoscaler.metrics import MetricsRegistry
 from nix_builder_autoscaler.models import SlotState
 from nix_builder_autoscaler.providers.clock import FakeClock
@@ -18,12 +18,16 @@ from nix_builder_autoscaler.state_db import StateDB
 def _make_client(
     *,
     reconcile_now: Any = None,  # noqa: ANN401
+    auth_token: str = "",
 ) -> tuple[TestClient, StateDB, FakeClock, MetricsRegistry]:
     clock = FakeClock()
     db = StateDB(":memory:", clock=clock)
     db.init_schema()
     db.init_slots("slot", 3, "x86_64-linux", "all")
-    config = AppConfig(capacity=CapacityConfig(reservation_ttl_seconds=1200))
+    config = AppConfig(
+        server=ServerConfig(auth_token=auth_token),
+        capacity=CapacityConfig(reservation_ttl_seconds=1200),
+    )
     metrics = MetricsRegistry()
     app = create_app(db, config, clock, metrics, reconcile_now=reconcile_now)
     return TestClient(app), db, clock, metrics
@@ -245,3 +249,20 @@ def test_admin_reconcile_now_success() -> None:
     assert response.json()["status"] == "accepted"
     assert response.json()["triggered"] is True
     assert called["value"] is True
+
+
+def test_auth_token_required_for_v1_when_configured() -> None:
+    client, _, _, _ = _make_client(auth_token="test-token")
+    response = client.post("/v1/reservations", json={"system": "x86_64-linux", "reason": "test"})
+    assert response.status_code == 401
+    assert response.json()["error"]["code"] == "unauthorized"
+
+
+def test_auth_token_allows_v1_when_header_matches() -> None:
+    client, _, _, _ = _make_client(auth_token="test-token")
+    response = client.post(
+        "/v1/reservations",
+        json={"system": "x86_64-linux", "reason": "test"},
+        headers={"Authorization": "Bearer test-token"},
+    )
+    assert response.status_code == 200

buildbot-ext/buildbot_autoscale_ext/client.py

@@ -7,6 +7,7 @@ import socket
 import time
 from dataclasses import dataclass
 from typing import Any
+from urllib.parse import urlparse
 
 
 @dataclass(frozen=True)
@@ -45,10 +46,39 @@ class UnixSocketHTTPConnection(http.client.HTTPConnection):
 
 
 class DaemonClient:
-    def __init__(self, socket_path: str, retry_policy: RetryPolicy) -> None:
+    def __init__(
+        self,
+        *,
+        retry_policy: RetryPolicy,
+        socket_path: str | None = None,
+        base_url: str | None = None,
+        auth_token: str | None = None,
+    ) -> None:
+        if (socket_path is None) == (base_url is None):
+            raise ValueError("exactly one of socket_path or base_url must be set")
         self._socket_path = socket_path
+        self._base_url = base_url
+        self._auth_token = auth_token.strip() if auth_token is not None else None
         self._retry = retry_policy
 
+        self._base_path = ""
+        self._http_scheme = "http"
+        self._http_host = "localhost"
+        self._http_port = 80
+        if base_url is not None:
+            parsed = urlparse(base_url)
+            if parsed.scheme not in {"http", "https"}:
+                raise ValueError("base_url must use http or https scheme")
+            if parsed.hostname is None:
+                raise ValueError("base_url must include a hostname")
+            self._http_scheme = parsed.scheme
+            self._http_host = parsed.hostname
+            if parsed.port is not None:
+                self._http_port = parsed.port
+            elif parsed.scheme == "https":
+                self._http_port = 443
+            self._base_path = parsed.path.rstrip("/")
+
     def post_json(
         self,
         path: str,
@@ -136,12 +166,31 @@ class DaemonClient:
         timeout_seconds: float,
         payload: bytes | None,
     ) -> tuple[bytes, int]:
-        conn = UnixSocketHTTPConnection(self._socket_path, timeout=timeout_seconds)
+        request_path = path if path.startswith("/") else f"/{path}"
+        if self._base_path != "":
+            request_path = f"{self._base_path}{request_path}"
+
         headers = {"Accept": "application/json"}
         if payload is not None:
             headers["Content-Type"] = "application/json"
+        if self._auth_token is not None:
+            headers["Authorization"] = f"Bearer {self._auth_token}"
+
+        conn: http.client.HTTPConnection
+        if self._socket_path is not None:
+            conn = UnixSocketHTTPConnection(self._socket_path, timeout=timeout_seconds)
+        else:
+            conn = (
+                http.client.HTTPSConnection(
+                    self._http_host, self._http_port, timeout=timeout_seconds
+                )
+                if self._http_scheme == "https"
+                else http.client.HTTPConnection(
+                    self._http_host, self._http_port, timeout=timeout_seconds
+                )
+            )
         try:
-            conn.request(method=method, url=path, body=payload, headers=headers)
+            conn.request(method=method, url=request_path, body=payload, headers=headers)
             response = conn.getresponse()
             data = response.read()
             return data, response.status

buildbot-ext/buildbot_autoscale_ext/configurator.py

@@ -34,6 +34,8 @@ class AutoscaleConfigurator(ConfiguratorBase):
             gate = CapacityGateStep(
                 name="Ensure remote builder capacity",
                 daemon_socket=self.settings.daemon_socket,
+                daemon_url=self.settings.daemon_url,
+                daemon_auth_token=self.settings.daemon_auth_token,
                 system_property=self.settings.system_property,
                 default_system=self.settings.default_system,
                 reserve_timeout_seconds=self.settings.reserve_timeout_seconds,
@@ -52,6 +54,8 @@ class AutoscaleConfigurator(ConfiguratorBase):
                     CapacityReleaseStep(
                         name="Release autoscaler reservation",
                         daemon_socket=self.settings.daemon_socket,
+                        daemon_url=self.settings.daemon_url,
+                        daemon_auth_token=self.settings.daemon_auth_token,
                         retry_max_attempts=self.settings.retry_max_attempts,
                         retry_base_seconds=self.settings.retry_base_seconds,
                         retry_max_seconds=self.settings.retry_max_seconds,

buildbot-ext/buildbot_autoscale_ext/settings.py

@@ -3,7 +3,9 @@ from dataclasses import dataclass
 
 @dataclass(frozen=True)
 class AutoscaleSettings:
-    daemon_socket: str
+    daemon_socket: str | None = "/run/nix-builder-autoscaler/daemon.sock"
+    daemon_url: str | None = None
+    daemon_auth_token: str | None = None
     system_property: str = "system"
     default_system: str = "x86_64-linux"
     reserve_timeout_seconds: int = 900

buildbot-ext/buildbot_autoscale_ext/steps.py

@@ -20,7 +20,9 @@ class CapacityGateStep(buildstep.BuildStep):
     def __init__(
         self,
         *,
-        daemon_socket: str,
+        daemon_socket: str | None = None,
+        daemon_url: str | None = None,
+        daemon_auth_token: str | None = None,
         system_property: str,
         default_system: str,
         reserve_timeout_seconds: int,
@@ -36,12 +38,14 @@ class CapacityGateStep(buildstep.BuildStep):
         self._reserve_timeout_seconds = reserve_timeout_seconds
         self._poll_interval_seconds = poll_interval_seconds
         self._client = DaemonClient(
-            socket_path=daemon_socket,
             retry_policy=RetryPolicy(
                 max_attempts=retry_max_attempts,
                 base_seconds=retry_base_seconds,
                 max_seconds=retry_max_seconds,
             ),
+            socket_path=daemon_socket,
+            base_url=daemon_url,
+            auth_token=daemon_auth_token,
         )
 
     def _determine_system(self) -> str:
@@ -155,7 +159,9 @@ class CapacityReleaseStep(buildstep.BuildStep):
     def __init__(
         self,
         *,
-        daemon_socket: str,
+        daemon_socket: str | None = None,
+        daemon_url: str | None = None,
+        daemon_auth_token: str | None = None,
         retry_max_attempts: int,
         retry_base_seconds: float,
         retry_max_seconds: float = 5.0,
@@ -163,12 +169,14 @@ class CapacityReleaseStep(buildstep.BuildStep):
     ) -> None:
         super().__init__(**kwargs)
         self._client = DaemonClient(
-            socket_path=daemon_socket,
             retry_policy=RetryPolicy(
                 max_attempts=retry_max_attempts,
                 base_seconds=retry_base_seconds,
                 max_seconds=retry_max_seconds,
             ),
+            socket_path=daemon_socket,
+            base_url=daemon_url,
+            auth_token=daemon_auth_token,
         )
 
     def run(self) -> defer.Deferred[int]:

buildbot-ext/buildbot_autoscale_ext/tests/test_client.py

@@ -9,7 +9,7 @@ from collections.abc import Callable
 from contextlib import suppress
 from dataclasses import dataclass
 from http import HTTPStatus
-from http.server import BaseHTTPRequestHandler
+from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
 from pathlib import Path
 from typing import Any
 
@@ -95,6 +95,87 @@ class FakeDaemon:
             os.unlink(self._socket_path)
 
 
+class _TCPHTTPServer(ThreadingHTTPServer):
+    def __init__(
+        self,
+        *,
+        on_get: Callable[[str, int], tuple[int, dict[str, Any]]],
+        on_post: Callable[[str, dict[str, Any], int], tuple[int, dict[str, Any]]],
+        expected_auth: str | None = None,
+    ) -> None:
+        self.on_get = on_get
+        self.on_post = on_post
+        self.expected_auth = expected_auth
+        self.state = ServerState()
+        super().__init__(("127.0.0.1", 0), _TCPHandler)
+
+
+class _TCPHandler(BaseHTTPRequestHandler):
+    server: _TCPHTTPServer
+
+    def _authorize(self) -> bool:
+        expected = self.server.expected_auth
+        if expected is None:
+            return True
+        return self.headers.get("Authorization") == f"Bearer {expected}"
+
+    def do_GET(self) -> None:  # noqa: N802
+        if not self._authorize():
+            self._send(HTTPStatus.UNAUTHORIZED, {"error": "unauthorized"})
+            return
+        self.server.state.get_count += 1
+        status, body = self.server.on_get(self.path, self.server.state.get_count)
+        self._send(status, body)
+
+    def do_POST(self) -> None:  # noqa: N802
+        if not self._authorize():
+            self._send(HTTPStatus.UNAUTHORIZED, {"error": "unauthorized"})
+            return
+        self.server.state.post_count += 1
+        size = int(self.headers.get("Content-Length", "0"))
+        raw = self.rfile.read(size) if size else b"{}"
+        payload = json.loads(raw.decode("utf-8"))
+        status, body = self.server.on_post(self.path, payload, self.server.state.post_count)
+        self._send(status, body)
+
+    def log_message(self, format: str, *args: object) -> None:
+        del format, args
+
+    def _send(self, status: int, body: dict[str, Any]) -> None:
+        encoded = json.dumps(body).encode("utf-8")
+        self.send_response(status)
+        self.send_header("Content-Type", "application/json")
+        self.send_header("Content-Length", str(len(encoded)))
+        self.end_headers()
+        self.wfile.write(encoded)
+
+
+class FakeTCPDaemon:
+    def __init__(
+        self,
+        *,
+        on_get: Callable[[str, int], tuple[int, dict[str, Any]]],
+        on_post: Callable[[str, dict[str, Any], int], tuple[int, dict[str, Any]]],
+        expected_auth: str | None = None,
+    ) -> None:
+        self._server = _TCPHTTPServer(on_get=on_get, on_post=on_post, expected_auth=expected_auth)
+        self._thread = threading.Thread(target=self._server.serve_forever, daemon=True)
+
+    @property
+    def base_url(self) -> str:
+        host, port = self._server.server_address
+        return f"http://{host}:{port}"
+
+    def __enter__(self) -> FakeTCPDaemon:
+        self._thread.start()
+        return self
+
+    def __exit__(self, exc_type: object, exc: object, tb: object) -> None:
+        del exc_type, exc, tb
+        self._server.shutdown()
+        self._server.server_close()
+
+
 @pytest.fixture
 def socket_path() -> str:
     with tempfile.TemporaryDirectory() as tmp:
@@ -210,3 +291,23 @@ def test_backoff_attempts_at_least_two(socket_path: str) -> None:
         )
 
     assert daemon._server.state.get_count >= 2
+
+
+def test_get_json_success_over_http_with_auth() -> None:
+    with FakeTCPDaemon(
+        on_get=lambda _p, _a: (HTTPStatus.OK, {"phase": "ready"}),
+        on_post=lambda _p, _payload, _a: (HTTPStatus.OK, {}),
+        expected_auth="test-token",
+    ) as daemon:
+        client = DaemonClient(
+            base_url=daemon.base_url,
+            auth_token="test-token",
+            retry_policy=RetryPolicy(max_attempts=2, base_seconds=0.001, max_seconds=0.01),
+        )
+        response = client.get_json(
+            "/v1/reservations/r1",
+            timeout_seconds=1.0,
+            retryable_statuses={429, 500, 503},
+        )
+
+    assert response == {"phase": "ready"}

nix/modules/nixos/services/buildbot-nix-autoscaler.nix

@@ -25,6 +25,18 @@ in
       description = "Autoscaler daemon Unix socket path for Buildbot gate/release steps.";
     };
 
+    daemonUrl = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = "Optional autoscaler daemon HTTP(S) endpoint URL for remote gate/release calls.";
+    };
+
+    daemonAuthTokenFile = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = "Optional file containing bearer token for authenticated daemon API calls.";
+    };
+
     defaultSystem = lib.mkOption {
       type = lib.types.str;
       default = "x86_64-linux";
@@ -131,6 +143,10 @@ in
         assertion = cfg.builderClusterHost != null;
         message = "services.buildbot-nix.nix-build-autoscaler.builderClusterHost must be set.";
       }
+      {
+        assertion = cfg.daemonUrl != null || cfg.daemonSocket != "";
+        message = "services.buildbot-nix.nix-build-autoscaler requires either daemonUrl or daemonSocket.";
+      }
     ];
 
     services.buildbot-master.pythonPackages = ps: [
@@ -149,6 +165,7 @@ in
     ];
 
     services.buildbot-master.extraImports = ''
+      import pathlib
       from buildbot_autoscale_ext.configurator import AutoscaleConfigurator
       from buildbot_autoscale_ext.settings import AutoscaleSettings
     '';
@@ -157,7 +174,14 @@ in
       ''
         AutoscaleConfigurator(
           AutoscaleSettings(
-            daemon_socket="${cfg.daemonSocket}",
+            daemon_socket=${if cfg.daemonUrl == null then ''"${cfg.daemonSocket}"'' else "None"},
+            daemon_url=${if cfg.daemonUrl != null then ''"${cfg.daemonUrl}"'' else "None"},
+            daemon_auth_token=${
+              if cfg.daemonAuthTokenFile != null then
+                ''pathlib.Path("${cfg.daemonAuthTokenFile}").read_text(encoding="utf-8").strip()''
+              else
+                "None"
+            },
             default_system="${cfg.defaultSystem}",
             reserve_timeout_seconds=${toString cfg.reserveTimeoutSeconds},
             poll_interval_seconds=${toString cfg.pollIntervalSeconds},

nix/modules/nixos/services/nix-builder-autoscaler.nix

@@ -45,6 +45,24 @@ in
       description = "Unix socket path exposed by the autoscaler API server.";
     };
 
+    listenHost = lib.mkOption {
+      type = lib.types.str;
+      default = "127.0.0.1";
+      description = "TCP listen host for the autoscaler API server when listenPort is set.";
+    };
+
+    listenPort = lib.mkOption {
+      type = lib.types.nullOr lib.types.int;
+      default = null;
+      description = "Optional TCP listen port for the autoscaler API server. Null keeps Unix socket mode.";
+    };
+
+    authTokenFile = lib.mkOption {
+      type = lib.types.nullOr lib.types.str;
+      default = null;
+      description = "Optional file containing bearer token required for /v1 and /metrics API requests.";
+    };
+
     logLevel = lib.mkOption {
       type = lib.types.str;
       default = "info";
@@ -287,6 +305,10 @@ in
         assertion = !cfg.capacity.nestedVirtualization || cfg.aws.onDemandLaunchTemplateIdFile != null;
         message = "services.nix-builder-autoscaler.aws.onDemandLaunchTemplateIdFile must be set when capacity.nestedVirtualization is true.";
       }
+      {
+        assertion = cfg.listenPort == null || (cfg.listenPort >= 1 && cfg.listenPort <= 65535);
+        message = "services.nix-builder-autoscaler.listenPort must be null or a TCP port between 1 and 65535.";
+      }
     ];
 
     environment.systemPackages = [ cfg.package ];
@@ -338,10 +360,16 @@ in
                 ${lib.optionalString (cfg.aws.assumeRoleArnFile != null) ''
                   assume_role_arn="$(tr -d '\n' < ${lib.escapeShellArg cfg.aws.assumeRoleArnFile})"
                 ''}
+                ${lib.optionalString (cfg.authTokenFile != null) ''
+                  auth_token="$(tr -d '\n' < ${lib.escapeShellArg cfg.authTokenFile})"
+                ''}
 
                 cat > ${generatedConfigPath} <<EOF
         [server]
         socket_path = "${cfg.socketPath}"
+        listen_host = "${cfg.listenHost}"
+        listen_port = ${toString (if cfg.listenPort != null then cfg.listenPort else 0)}
+        ${lib.optionalString (cfg.authTokenFile != null) ''auth_token = "$auth_token"''}
         log_level = "${cfg.logLevel}"
         db_path = "${cfg.dbPath}"