feat: add support of openmetrics (#144)

* feat: add openmetrics support & endpoint

* add support of named resources

* update docstrings

* generate docs

* add another test for http api

src/ahriman/web/middlewares/metrics_handler.py

@@ -0,0 +1,69 @@
+#
+# Copyright (c) 2021-2025 ahriman team.
+#
+# This file is part of ahriman
+# (see https://github.com/arcan1s/ahriman).
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+try:
+    import aiohttp_openmetrics
+except ImportError:
+    aiohttp_openmetrics = None  # type: ignore[assignment]
+
+from aiohttp.typedefs import Middleware
+from aiohttp.web import HTTPNotFound, Request, Response, StreamResponse, middleware
+
+from ahriman.web.middlewares import HandlerType
+
+
+__all__ = [
+    "metrics",
+    "metrics_handler",
+]
+
+
+async def metrics(request: Request) -> Response:
+    """
+    handler for returning metrics
+
+    Args:
+        request(Request): request object
+
+    Returns:
+        Response: response object
+
+    Raises:
+        HTTPNotFound: endpoint is disabled
+    """
+    if aiohttp_openmetrics is None:
+        raise HTTPNotFound
+    return await aiohttp_openmetrics.metrics(request)
+
+
+def metrics_handler() -> Middleware:
+    """
+    middleware for metrics support
+
+    Returns:
+        Middleware: middleware function to handle server metrics
+    """
+    if aiohttp_openmetrics is not None:
+        return aiohttp_openmetrics.metrics_middleware
+
+    @middleware
+    async def handle(request: Request, handler: HandlerType) -> StreamResponse:
+        return await handler(request)
+
+    return handle

src/ahriman/web/routes.py

@@ -17,6 +17,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 #
+import re
+
 from aiohttp.web import Application, View
 from collections.abc import Generator
 
@@ -45,6 +47,23 @@ def _dynamic_routes(configuration: Configuration) -> Generator[tuple[str, type[V
             yield route, view
 
 
+def _identifier(route: str) -> str:
+    """
+    extract valid route identifier (aka name) for the route. This method replaces curly brackets by single colon
+    and replaces other special symbols (including slashes) by underscore
+
+    Args:
+        route(str): source route
+
+    Returns:
+        str: route with special symbols being replaced
+    """
+    # replace special symbols
+    alphanum = re.sub(r"[^A-Za-z\d\-{}]", "_", route)
+    # finally replace curly brackets
+    return alphanum.replace("{", ":").replace("}", "")
+
+
 def setup_routes(application: Application, configuration: Configuration) -> None:
     """
     setup all defined routes
@@ -53,7 +72,8 @@ def setup_routes(application: Application, configuration: Configuration) -> None
         application(Application): web application instance
         configuration(Configuration): configuration instance
     """
-    application.router.add_static("/static", configuration.getpath("web", "static_path"), follow_symlinks=True)
+    application.router.add_static("/static", configuration.getpath("web", "static_path"), name="_static",
+                                  follow_symlinks=True)
 
     for route, view in _dynamic_routes(configuration):
-        application.router.add_view(route, view)
+        application.router.add_view(route, view, name=_identifier(route))

src/ahriman/web/schemas/__init__.py

@@ -17,6 +17,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program. If not, see <http://www.gnu.org/licenses/>.
 #
+from ahriman.web.schemas.any_schema import AnySchema
 from ahriman.web.schemas.aur_package_schema import AURPackageSchema
 from ahriman.web.schemas.auth_schema import AuthSchema
 from ahriman.web.schemas.build_options_schema import BuildOptionsSchema

src/ahriman/web/schemas/any_schema.py

@@ -0,0 +1,26 @@
+#
+# Copyright (c) 2021-2025 ahriman team.
+#
+# This file is part of ahriman
+# (see https://github.com/arcan1s/ahriman).
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+from ahriman.web.apispec import Schema
+
+
+class AnySchema(Schema):
+    """
+    response dummy schema
+    """

src/ahriman/web/views/base.py

@@ -167,6 +167,9 @@ class BaseView(View, CorsViewMixin):
         """
         HEAD method implementation based on the result of GET method
 
+        Returns:
+            StreamResponse: generated response for the request
+
         Raises:
             HTTPMethodNotAllowed: in case if there is no GET method implemented
         """

src/ahriman/web/views/v1/packages/packages.py

@@ -46,7 +46,7 @@ class PackagesView(StatusViewGuard, BaseView):
     ROUTES = ["/api/v1/packages"]
 
     @apidocs(
-        tags=["packages"],
+        tags=["Packages"],
         summary="Get packages list",
         description="Retrieve packages and their descriptors",
         permission=GET_PERMISSION,

src/ahriman/web/views/v1/status/metrics.py

@@ -0,0 +1,56 @@
+#
+# Copyright (c) 2021-2025 ahriman team.
+#
+# This file is part of ahriman
+# (see https://github.com/arcan1s/ahriman).
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+from aiohttp.web import Response
+from typing import ClassVar
+
+from ahriman.models.user_access import UserAccess
+from ahriman.web.apispec.decorators import apidocs
+from ahriman.web.middlewares.metrics_handler import metrics
+from ahriman.web.schemas import AnySchema
+from ahriman.web.views.base import BaseView
+
+
+class MetricsView(BaseView):
+    """
+    open metrics endpoints
+
+    Attributes:
+        GET_PERMISSION(UserAccess): (class attribute) get permissions of self
+    """
+
+    GET_PERMISSION: ClassVar[UserAccess] = UserAccess.Unauthorized
+    ROUTES = ["/api/v1/metrics"]
+
+    @apidocs(
+        tags=["Status"],
+        summary="OpenMetrics endpoint",
+        description="Get service metrics in OpenMetrics format",
+        permission=GET_PERMISSION,
+        error_404_description="Endpoint is disabled",
+        schema=AnySchema,
+    )
+    async def get(self) -> Response:
+        """
+        get service HTTP metrics
+
+        Returns:
+            Response: 200 with service metrics as generated by the library
+        """
+        return await metrics(self.request)

src/ahriman/web/web.py

@@ -37,6 +37,7 @@ from ahriman.web.apispec.info import setup_apispec
 from ahriman.web.cors import setup_cors
 from ahriman.web.keys import AuthKey, ConfigurationKey, SpawnKey, WatcherKey, WorkersKey
 from ahriman.web.middlewares.exception_handler import exception_handler
+from ahriman.web.middlewares.metrics_handler import metrics_handler
 from ahriman.web.routes import setup_routes
 
 
@@ -146,6 +147,7 @@ def setup_server(configuration: Configuration, spawner: Spawn, repositories: lis
 
     application.middlewares.append(normalize_path_middleware(append_slash=False, remove_slash=True))
     application.middlewares.append(exception_handler(application.logger))
+    application.middlewares.append(metrics_handler())
 
     application.logger.info("setup routes")
     setup_routes(application, configuration)