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

docker/Dockerfile

@@ -40,6 +40,7 @@ RUN pacman -S --noconfirm --asdeps \
     pacman -S --noconfirm --asdeps \
         git \
         python-aiohttp \
+        python-aiohttp-openmetrics \
         python-boto3 \
         python-cerberus \
         python-cryptography \
@@ -112,6 +113,7 @@ RUN pacman -S --noconfirm ahriman
 RUN pacman -S --noconfirm --asdeps \
         python-aioauth-client \
         python-aiohttp-apispec-git \
+        python-aiohttp-openmetrics \
         python-aiohttp-security \
         python-aiohttp-session \
         python-boto3 \

docs/ahriman.web.middlewares.rst

@@ -20,6 +20,14 @@ ahriman.web.middlewares.exception\_handler module
    :no-undoc-members:
    :show-inheritance:
 
+ahriman.web.middlewares.metrics\_handler module
+-----------------------------------------------
+
+.. automodule:: ahriman.web.middlewares.metrics_handler
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+
 Module contents
 ---------------
 

docs/ahriman.web.schemas.rst

@@ -4,6 +4,14 @@ ahriman.web.schemas package
 Submodules
 ----------
 
+ahriman.web.schemas.any\_schema module
+--------------------------------------
+
+.. automodule:: ahriman.web.schemas.any_schema
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+
 ahriman.web.schemas.aur\_package\_schema module
 -----------------------------------------------
 

docs/ahriman.web.views.v1.status.rst

@@ -12,6 +12,14 @@ ahriman.web.views.v1.status.info module
    :no-undoc-members:
    :show-inheritance:
 
+ahriman.web.views.v1.status.metrics module
+------------------------------------------
+
+.. automodule:: ahriman.web.views.v1.status.metrics
+   :members:
+   :no-undoc-members:
+   :show-inheritance:
+
 ahriman.web.views.v1.status.repositories module
 -----------------------------------------------
 

package/archlinux/PKGBUILD

@@ -75,6 +75,7 @@ package_ahriman-web() {
     depends=("$pkgbase-core=$pkgver" 'python-aiohttp-cors' 'python-aiohttp-jinja2')
     optdepends=('python-aioauth-client: OAuth2 authorization support'
                 'python-aiohttp-apispec>=3.0.0: autogenerated API documentation'
+                'python-aiohttp-openmetrics: HTTP metrics support'
                 'python-aiohttp-security: authorization support'
                 'python-aiohttp-session: authorization support'
                 'python-cryptography: authorization support')

pyproject.toml

@@ -69,6 +69,10 @@ web_auth = [
     "aiohttp_security",
     "cryptography",
 ]
+web_metrics = [
+    "ahriman[web]",
+    "aiohttp-openmetrics",
+]
 web_oauth2 = [
     "ahriman[web_auth]",
     "aioauth-client",

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)

tests/ahriman/web/middlewares/test_metrics_handler.py

@@ -0,0 +1,59 @@
+import importlib
+import pytest
+import sys
+
+from aiohttp.web import HTTPNotFound
+from pytest_mock import MockerFixture
+from unittest.mock import AsyncMock
+
+import ahriman.web.middlewares.metrics_handler as metrics_handler
+
+
+async def test_metrics(mocker: MockerFixture) -> None:
+    """
+    must return metrics methods if library is available
+    """
+    metrics_mock = AsyncMock()
+    mocker.patch.object(metrics_handler, "aiohttp_openmetrics", metrics_mock)
+
+    await metrics_handler.metrics(42)
+    metrics_mock.metrics.assert_called_once_with(42)
+
+
+async def test_metrics_dummy(mocker: MockerFixture) -> None:
+    """
+    must raise HTTPNotFound if no module found
+    """
+    mocker.patch.object(metrics_handler, "aiohttp_openmetrics", None)
+    with pytest.raises(HTTPNotFound):
+        await metrics_handler.metrics(None)
+
+
+async def test_metrics_handler() -> None:
+    """
+    must return metrics handler if library is available
+    """
+    assert metrics_handler.metrics_handler() == metrics_handler.aiohttp_openmetrics.metrics_middleware
+
+
+async def test_metrics_handler_dummy(mocker: MockerFixture) -> None:
+    """
+    must return dummy handler if no module found
+    """
+    mocker.patch.object(metrics_handler, "aiohttp_openmetrics", None)
+    handler = metrics_handler.metrics_handler()
+
+    async def handle(result: int) -> int:
+        return result
+
+    assert await handler(42, handle) == 42
+
+
+def test_import_openmetrics_missing(mocker: MockerFixture) -> None:
+    """
+    must correctly process missing module
+    """
+    mocker.patch.dict(sys.modules, {"aiohttp_openmetrics": None})
+    importlib.reload(metrics_handler)
+
+    assert metrics_handler.aiohttp_openmetrics is None

tests/ahriman/web/schemas/test_any_schema.py

@@ -0,0 +1 @@
+# schema testing goes in view class tests

tests/ahriman/web/test_routes.py

@@ -3,7 +3,7 @@ from pathlib import Path
 
 from ahriman.core.configuration import Configuration
 from ahriman.core.utils import walk
-from ahriman.web.routes import _dynamic_routes, setup_routes
+from ahriman.web.routes import _dynamic_routes, _identifier, setup_routes
 
 
 def test_dynamic_routes(resource_path_root: Path, configuration: Configuration) -> None:
@@ -22,9 +22,19 @@ def test_dynamic_routes(resource_path_root: Path, configuration: Configuration)
     assert len(set(routes.values())) == len(expected_views)
 
 
+def test_identifier() -> None:
+    """
+    must correctly extract route identifiers
+    """
+    assert _identifier("/") == "_"
+    assert _identifier("/api/v1/status") == "_api_v1_status"
+    assert _identifier("/api/v1/packages/{package}") == "_api_v1_packages_:package"
+
+
 def test_setup_routes(application: Application, configuration: Configuration) -> None:
     """
     must generate non-empty list of routes
     """
+    application.router._named_resources = {}
     setup_routes(application, configuration)
     assert application.router.routes()

tests/ahriman/web/views/v1/status/test_view_v1_status_metrics.py

@@ -0,0 +1,50 @@
+import pytest
+
+from aiohttp.test_utils import TestClient
+from aiohttp.web import Response
+from pytest_mock import MockerFixture
+
+import ahriman.web.middlewares.metrics_handler as metrics_handler
+
+from ahriman.models.user_access import UserAccess
+from ahriman.web.views.v1.status.metrics import MetricsView
+
+
+async def test_get_permission() -> None:
+    """
+    must return correct permission for the request
+    """
+    for method in ("GET",):
+        request = pytest.helpers.request("", "", method)
+        assert await MetricsView.get_permission(request) == UserAccess.Unauthorized
+
+
+def test_routes() -> None:
+    """
+    must return correct routes
+    """
+    assert MetricsView.ROUTES == ["/api/v1/metrics"]
+
+
+async def test_get(client: TestClient, mocker: MockerFixture) -> None:
+    """
+    must return service metrics
+    """
+    metrics_mock = mocker.patch("ahriman.web.views.v1.status.metrics.metrics", return_value=Response())
+
+    response = await client.get("/api/v1/metrics")
+    assert response.ok
+    # there is no response validation here, because it is free text, so we check call instead
+    metrics_mock.assert_called_once_with(pytest.helpers.anyvar(int))
+
+
+async def test_get_not_found(client: TestClient, mocker: MockerFixture) -> None:
+    """
+    must return 404 error if no module found
+    """
+    mocker.patch.object(metrics_handler, "aiohttp_openmetrics", None)
+    response_schema = pytest.helpers.schema_response(MetricsView.get, code=404)
+
+    response = await client.get("/api/v1/metrics")
+    assert response.status == 404
+    assert not response_schema.validate(await response.json())

tox.ini

@@ -3,7 +3,7 @@ envlist = check, tests
 isolated_build = true
 labels =
 	release = version, docs, publish
-dependencies = -e .[journald,pacman,reports,s3,shell,stats,unixsocket,validator,web,web_api-docs,web_auth,web_oauth2]
+dependencies = -e .[journald,pacman,reports,s3,shell,stats,unixsocket,validator,web,web_api-docs,web_auth,web_oauth2,web_metrics]
 project_name = ahriman
 
 [mypy]