Add integration for FastAPI (#81)

* Add tox config for FastAPI 100

* Add dockerflow router to package root

* Add request summary middleware

* Add version endpoint and tests

* Add initial heartbeat route, check mechanism, and tests

* Refactor package structure, names of things

- Define "router" in package init, register view functions defined in views
  module
- Add test for check with custom name
- use better name for check operations

* Leverage centralized checks (#85)

* Do not test on Python 3.7

* Add 'taskName' to excluded fields

* Test with python 3.12

* Improve test coverage of FastAPI

* Blackify

* FastAPI integration docs (#95)

* Add FastAPI documentation

* Update docs/fastapi.rst

Co-authored-by: grahamalama <graham.beckley@gmail.com>

* Mention APP_DIR for the version file

---------

Co-authored-by: grahamalama <graham.beckley@gmail.com>

* Update tox.ini

Co-authored-by: grahamalama <graham.beckley@gmail.com>

---------

Co-authored-by: Mathieu Leplatre <mathieu@mozilla.com>

docs/api/fastapi.rst

@@ -0,0 +1,11 @@
+FastAPI
+=======
+
+This documents the various FastAPI specific functionality but doesn't cover
+internals of the extension.
+
+Extension
+---------
+
+.. automodule:: dockerflow.fastapi
+   :members: router

docs/fastapi.rst

@@ -0,0 +1,325 @@
+FastAPI
+=======
+
+The package ``dockerflow.fastapi`` package implements various tools to support
+`FastAPI`_ based projects that want to follow the Dockerflow specs:
+
+- A Python logging formatter following the `mozlog`_ format.
+
+- A FastAPI extension implements:
+
+  - Emitting of `request.summary`_ log records based on request specific data.
+
+  - Views for health monitoring:
+
+    - ``/__version__`` - Serves a ``version.json`` file
+
+    - ``/__heartbeat__`` - Runs the configured Dockerflow checks
+
+    - ``/__lbheartbeat__`` - Retuns a HTTP 200 response
+
+  - Hooks to add custom Dockerflow checks.
+
+.. _`FastAPI`: https://fastapi.tiangolo.com
+.. _`mozlog`: https://github.com/mozilla-services/Dockerflow/blob/main/docs/mozlog.md
+.. _`request.summary`: https://github.com/mozilla-services/Dockerflow/blob/main/docs/mozlog.md#application-request-summary-type-requestsummary
+
+.. seealso::
+
+    For more information see the :doc:`API documentation <api/fastapi>` for
+    the ``dockerflow.fastapi`` module.
+
+Setup
+-----
+
+To install ``python-dockerflow``'s FastAPI support please follow these steps:
+
+#. In your code where your FastAPI application lives set up the dockerflow FastAPI
+   extension::
+
+     from fastapi import FastAPI
+     from dockerflow.fastapi import router
+     from dockerflow.fastapi.middleware import MozlogRequestSummaryLogger
+
+     app = FastAPI()
+     app.include_router(router)
+     app.add_middleware(MozlogRequestSummaryLogger)
+
+#. Make sure the app root path is set correctly as this will be used
+   to locate the ``version.json`` file that is generated by
+   your CI or another process during deployment.
+
+   .. seealso:: :ref:`fastapi-versions` for more information
+
+#. Configure logging to use the ``JsonLogFormatter`` logging formatter for the
+   ``request.summary`` logger (you may have to extend your existing logging
+   configuration), see :ref:`fastapi-logging` for more information.
+
+.. _fastapi-config:
+
+Configuration
+-------------
+
+.. epigraph::
+
+   Accept its configuration through environment variables.
+
+There are several options to handle configuration values through
+environment variables when configuring FastAPI.
+
+``pydantic-settings``
+~~~~~~~~~~~~~~~~~~~~~
+
+The simplest is to use `pydantic-settings`_ that will load settings from
+environment variables or secrets files, and turn them into model instance.
+
+.. code-block:: python
+
+    from pydantic_settings import BaseSettings
+
+    class Settings(BaseSettings):
+        port: int = 8000
+
+    settings = Settings()
+
+.. _pydantic-settings: https://docs.pydantic.dev/latest/concepts/pydantic_settings/
+
+.. _fastapi-serving:
+
+``PORT``
+--------
+
+.. epigraph::
+
+   Listen on environment variable ``$PORT`` for HTTP requests.
+
+Depending on which ASGI server you are using to run your Python application
+there are different ways to accept the :envvar:`PORT` as the port to launch
+your application with.
+
+It's recommended to use port ``8000`` by default.
+
+Uvicorn
+~~~~~~~
+
+.. code-block:: python
+
+    import uvicorn
+
+    from myapp import Settings
+
+    settings = Settings()
+
+    if __name__ == "__main__":
+        server = uvicorn.Server(
+            uvicorn.Config(
+                "myapp:app",
+                host=settings.host,
+                port=settings.port,
+                reload=settings.app_reload,
+                log_config=None,
+            )
+        )
+        server.run()
+
+.. _fastapi-versions:
+
+Versions
+--------
+
+.. epigraph::
+
+   Must have a JSON version object at /app/version.json.
+
+Dockerflow requires writing a `version object`_ to the file
+``/app/version.json`` as seen from the docker container to be served under
+the URL path ``/__version__``.
+
+.. note::
+
+    The default ``/app`` location can be customized using the ``APP_DIR``
+    environment variable.
+
+To facilitate this python-dockerflow comes with a FastAPI view to read the
+file under path the parent directory of the app root. See the
+:class:`FastAPI API docs <~fastapi.FastAPI>` for more information about the
+app root path.
+
+.. _version object: https://github.com/mozilla-services/Dockerflow/blob/main/docs/version_object.md
+
+.. _fastapi-health:
+
+Health monitoring
+-----------------
+
+Health monitoring happens via three different views following the Dockerflow_
+spec:
+
+.. http:get:: /__version__
+
+   The view that serves the :ref:`version information <fastapi-versions>`.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /__version__ HTTP/1.1
+      Host: example.com
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept-Encoding
+      Content-Type: application/json
+
+      {
+        "commit": "52ce614fbf99540a1bf6228e36be6cef63b4d73b",
+        "version": "2017.11.0",
+        "source": "https://github.com/mozilla/telemetry-analysis-service",
+        "build": "https://circleci.com/gh/mozilla/telemetry-analysis-service/2223"
+      }
+
+   :statuscode 200: no error
+   :statuscode 404: a version.json wasn't found
+
+.. http:get:: /__heartbeat__
+
+   The heartbeat view will go through the list of registered Dockerflow
+   checks, run each check and add their results to a JSON response.
+
+   The view will return HTTP responses with either an status code of 200 if
+   all checks ran successfully or 500 if there was one or more warnings or
+   errors returned by the checks.
+
+   Here's an example of a check that handles various levels of exceptions
+   from an external storage system with different check message::
+
+       from dockerflow import checks
+
+       @checks.register
+       def storage_reachable():
+           result = []
+           try:
+               acme.storage.ping()
+           except SlowConnectionException as exc:
+               result.append(checks.Warning(exc.msg, id='acme.health.0002'))
+           except StorageException as exc:
+               result.append(checks.Error(exc.msg, id='acme.health.0001'))
+           return result
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /__heartbeat__ HTTP/1.1
+      Host: example.com
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 500 Internal Server Error
+      Vary: Accept-Encoding
+      Content-Type: application/json
+
+      {
+        "status": "warning",
+        "checks": {
+          "check_debug": "ok",
+          "check_sts_preload": "warning"
+        },
+        "details": {
+          "check_sts_preload": {
+            "status": "warning",
+            "level": 30,
+            "messages": {
+              "security.W021": "You have not set the SECURE_HSTS_PRELOAD setting to True. Without this, your site cannot be submitted to the browser preload list."
+            }
+          }
+        }
+      }
+
+   :statuscode 200: no error
+   :statuscode 500: there was an error
+
+.. http:get:: /__lbheartbeat__
+
+   The view that simply returns a successful HTTP response so that a load
+   balancer in front of the application can check that the web application
+   has started up.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /__lbheartbeat__ HTTP/1.1
+      Host: example.com
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept-Encoding
+      Content-Type: application/json
+
+   :statuscode 200: no error
+
+.. _Dockerflow: https://github.com/mozilla-services/Dockerflow
+
+.. _fastapi-logging:
+
+Logging
+-------
+
+Dockerflow provides a :class:`~dockerflow.logging.JsonLogFormatter` Python
+logging formatter class.
+
+To use it, put something like this **BEFORE** your FastAPI app is initialized
+for at least the ``request.summary`` logger:
+
+.. code-block:: python
+
+    from logging.conf import dictConfig
+
+    dictConfig({
+        'version': 1,
+        'formatters': {
+            'json': {
+                '()': 'dockerflow.logging.JsonLogFormatter',
+                'logger_name': 'myproject'
+            }
+        },
+        'handlers': {
+            'console': {
+                'level': 'DEBUG',
+                'class': 'logging.StreamHandler',
+                'formatter': 'json'
+            },
+        },
+        'loggers': {
+            'request.summary': {
+                'handlers': ['console'],
+                'level': 'DEBUG',
+            },
+        }
+    })
+
+.. _fastapi-static:
+
+Static content
+--------------
+
+We recommend using default `FastAPI features <https://fastapi.tiangolo.com/reference/staticfiles/>`_ for static files:
+
+.. code-block:: python
+
+    from fastapi.staticfiles import StaticFiles
+
+    SRC_DIR = Path(__file__).parent
+
+    app = FastAPI()
+
+    app.mount("/static", StaticFiles(directory=SRC_DIR / "static"), name="static")

docs/index.rst

@@ -24,17 +24,17 @@ Features
    environment
 
       Accept its configuration through environment variables.
-      See: :ref:`Django <django-config>`, :ref:`Flask <flask-config>`, :ref:`Sanic <sanic-config>`
+      See: :ref:`Django <django-config>`, :ref:`FastAPI <fastapi-config>`, :ref:`Flask <flask-config>`, :ref:`Sanic <sanic-config>`
 
    port
 
       Listen on environment variable ``$PORT`` for HTTP requests.
-      See: :ref:`Django <django-serving>`, :ref:`Flask <flask-serving>`, :ref:`Sanic <sanic-serving>`
+      See: :ref:`Django <django-serving>`, :ref:`FastAPI <fastapi-serving>`, :ref:`Flask <flask-serving>`, :ref:`Sanic <sanic-serving>`
 
    version
 
       Must have a JSON version object at ``/app/version.json``.
-      See: :ref:`Django <django-versions>`, :ref:`Flask <flask-versions>`, :ref:`Sanic <sanic-versions>`
+      See: :ref:`Django <django-versions>`, :ref:`FastAPI <fastapi-versions>`, :ref:`Flask <flask-versions>`, :ref:`Sanic <sanic-versions>`
 
    health
 
@@ -44,18 +44,19 @@ Features
       * Respond to ``/__lbheartbeat__`` with an HTTP 200.
         This is for load balancer checks and should not check backing services.
 
-      See: :ref:`Django <django-health>`, :ref:`Flask <flask-health>`, :ref:`Sanic <sanic-health>`
+      See: :ref:`Django <django-health>`, :ref:`FastAPI <fastapi-health>`, :ref:`Flask <flask-health>`, :ref:`Sanic <sanic-health>`
 
    logging
 
       Send text logs to ``stdout`` or ``stderr``. See:
       :ref:`Generic <logging>`, :ref:`Django <django-logging>`,
+      :ref:`FastAPI <fastapi-logging>`,
       :ref:`Flask <flask-logging>`, :ref:`Sanic <sanic-logging>`
 
    static content
 
       Serve its own static content. See:
-      :ref:`Django <django-static>`, :ref:`Flask <flask-static>`, :ref:`Flask <sanic-static>`
+      :ref:`Django <django-static>`, logging:ref:`FastAPI <fastapi-static>`, :ref:`Flask <sanic-static>`
 
 Contents
 --------
@@ -69,6 +70,7 @@ Contents
    changelog
    logging
    django
+   fastapi
    flask
    sanic
    api/index

docs/requirements.txt

@@ -1,5 +1,6 @@
 -r ../tests/requirements/default.txt
 -r ../tests/requirements/docs.txt
 -r ../tests/requirements/django.txt
+-r ../tests/requirements/fastapi.txt
 -r ../tests/requirements/flask.txt
 -r ../tests/requirements/sanic.txt