feat(fcm) Add send_each_async and send_each_for_multicast_async for FCM async and HTTP/2 support

firebase_admin/_http_client.py

@@ -14,14 +14,23 @@
 
 """Internal HTTP client module.
 
- This module provides utilities for making HTTP calls using the requests library.
- """
-
-from google.auth import transport
-import requests
+This module provides utilities for making HTTP calls using the requests library.
+"""
+
+from __future__ import annotations
+import logging
+from typing import Any, Dict, Generator, Optional, Tuple, Union
+import httpx
+import requests.adapters
 from requests.packages.urllib3.util import retry # pylint: disable=import-error
+from google.auth import credentials
+from google.auth import transport
+from google.auth.transport import requests as google_auth_requests
 
 from firebase_admin import _utils
+from firebase_admin._retry import HttpxRetry, HttpxRetryTransport
+
+logger = logging.getLogger(__name__)
 
 if hasattr(retry.Retry.DEFAULT, 'allowed_methods'):
     _ANY_METHOD = {'allowed_methods': None}
@@ -34,6 +43,9 @@
     connect=1, read=1, status=4, status_forcelist=[500, 503],
     raise_on_status=False, backoff_factor=0.5, **_ANY_METHOD)
 
+DEFAULT_HTTPX_RETRY_CONFIG = HttpxRetry(
+    max_retries=4, status_forcelist=[500, 503], backoff_factor=0.5)
+
 
 DEFAULT_TIMEOUT_SECONDS = 120
 
@@ -144,7 +156,6 @@ def close(self):
         self._session.close()
         self._session = None
 
-
 class JsonHttpClient(HttpClient):
     """An HTTP client that parses response messages as JSON."""
 
@@ -153,3 +164,194 @@ def __init__(self, **kwargs):
 
     def parse_body(self, resp):
         return resp.json()
+
+class GoogleAuthCredentialFlow(httpx.Auth):
+    """Google Auth Credential Auth Flow"""
+    def __init__(self, credential: credentials.Credentials):
+        self._credential = credential
+        self._max_refresh_attempts = 2
+        self._refresh_status_codes = (401,)
+
+    def apply_auth_headers(
+            self,
+            request: httpx.Request,
+            auth_request: google_auth_requests.Request
+        ) -> None:
+        """A helper function to refreshes credentials if needed and mutates the request headers to
+        contain access token and any other google auth headers."""
+
+        logger.debug(
+            'Attempting to apply auth headers. Credential validity before: %s',
+            self._credential.valid
+        )
+        self._credential.before_request(
+            auth_request, request.method, str(request.url), request.headers
+        )
+        logger.debug('Auth headers applied. Credential validity after: %s', self._credential.valid)
+
+    def auth_flow(self, request: httpx.Request) -> Generator[httpx.Request, httpx.Response, None]:
+        _original_headers = request.headers.copy()
+        _credential_refresh_attempt = 0
+
+        # Create a Google auth request object to be used for refreshing credentials
+        auth_request = google_auth_requests.Request()
+
+        while True:
+            # Copy original headers for each attempt
+            request.headers = _original_headers.copy()
+
+            # Apply auth headers (which might include an implicit refresh if token is expired)
+            self.apply_auth_headers(request, auth_request)
+
+            logger.debug(
+                'Dispatching request, attempt %d of %d',
+                _credential_refresh_attempt, self._max_refresh_attempts
+            )
+            response: httpx.Response = yield request
+
+            if response.status_code in self._refresh_status_codes:
+                if _credential_refresh_attempt < self._max_refresh_attempts:
+                    logger.debug(
+                        'Received status %d. Attempting explicit credential refresh. \
+                        Attempt %d of %d.',
+                        response.status_code,
+                        _credential_refresh_attempt + 1,
+                        self._max_refresh_attempts
+                    )
+                    # Explicitly force a credentials refresh
+                    self._credential.refresh(auth_request)
+                    _credential_refresh_attempt += 1
+                else:
+                    logger.debug(
+                        'Received status %d, but max auth refresh attempts (%d) reached. \
+                        Returning last response.',
+                        response.status_code, self._max_refresh_attempts
+                    )
+                    break
+            else:
+                # Status code is not one that requires a refresh, so break and return response
+                logger.debug(
+                    'Status code %d does not require refresh. Returning response.',
+                    response.status_code
+                )
+                break
+        # The last yielded response is automatically returned by httpx's auth flow.
+
+class HttpxAsyncClient():
+    """Async HTTP client used to make HTTP/2 calls using HTTPX.
+
+    HttpxAsyncClient maintains an async HTTPX client, and handles request authentication and retries
+    if necessary.
+    """
+    def __init__(
+            self,
+            credential: Optional[credentials.Credentials] = None,
+            base_url: str = '',
+            headers: Optional[Union[httpx.Headers, Dict[str, str]]] = None,
+            retry_config: HttpxRetry = DEFAULT_HTTPX_RETRY_CONFIG,
+            timeout: int = DEFAULT_TIMEOUT_SECONDS,
+            http2: bool = True
+    ) -> None:
+        """Creates a new HttpxAsyncClient instance from the provided arguments.
+
+        If a credential is provided, initializes a new async HTTPX client authorized with it.
+        Otherwise, initializes a new unauthorized async HTTPX client.
+
+        Args:
+            credential: A Google credential that can be used to authenticate requests (optional).
+            base_url: A URL prefix to be added to all outgoing requests (optional).
+            headers: A map of headers to be added to all outgoing requests (optional).
+            retry_config: A HttpxRetry configuration. Default settings would retry up to 4 times for
+                HTTP 500 and 503 errors (optional).
+            timeout: HTTP timeout in seconds. Defaults to 120 seconds when not specified (optional).
+            http2: A boolean indicating if HTTP/2 support should be enabled. Defaults to `True` when
+                not specified (optional).
+        """
+        self._base_url = base_url
+        self._timeout = timeout
+        self._headers = {**headers, **METRICS_HEADERS} if headers else {**METRICS_HEADERS}
+        self._retry_config = retry_config
+
+        # Only set up retries on urls starting with 'http://' and 'https://'
+        self._mounts = {
+            'http://': HttpxRetryTransport(retry=self._retry_config, http2=http2),
+            'https://': HttpxRetryTransport(retry=self._retry_config, http2=http2)
+        }
+
+        if credential:
+            self._async_client = httpx.AsyncClient(
+                http2=http2,
+                timeout=self._timeout,
+                headers=self._headers,
+                auth=GoogleAuthCredentialFlow(credential), # Add auth flow for credentials.
+                mounts=self._mounts
+            )
+        else:
+            self._async_client = httpx.AsyncClient(
+                http2=http2,
+                timeout=self._timeout,
+                headers=self._headers,
+                mounts=self._mounts
+            )
+
+    @property
+    def base_url(self):
+        return self._base_url
+
+    @property
+    def timeout(self):
+        return self._timeout
+
+    @property
+    def async_client(self):
+        return self._async_client
+
+    async def request(self, method: str, url: str, **kwargs: Any) -> httpx.Response:
+        """Makes an HTTP call using the HTTPX library.
+
+        This is the sole entry point to the HTTPX library. All other helper methods in this
+        class call this method to send HTTP requests out. Refer to
+        https://www.python-httpx.org/api/ for more information on supported options
+        and features.
+
+        Args:
+            method: HTTP method name as a string (e.g. get, post).
+            url: URL of the remote endpoint.
+            **kwargs: An additional set of keyword arguments to be passed into the HTTPX API
+                (e.g. json, params, timeout).
+
+        Returns:
+            Response: An HTTPX response object.
+
+        Raises:
+            HTTPError: Any HTTPX exceptions encountered while making the HTTP call.
+            RequestException: Any requests exceptions encountered while making the HTTP call.
+        """
+        if 'timeout' not in kwargs:
+            kwargs['timeout'] = self.timeout
+        resp = await self._async_client.request(method, self.base_url + url, **kwargs)
+        return resp.raise_for_status()
+
+    async def headers(self, method: str, url: str, **kwargs: Any) -> httpx.Headers:
+        resp = await self.request(method, url, **kwargs)
+        return resp.headers
+
+    async def body_and_response(
+            self, method: str, url: str, **kwargs: Any) -> Tuple[Any, httpx.Response]:
+        resp = await self.request(method, url, **kwargs)
+        return self.parse_body(resp), resp
+
+    async def body(self, method: str, url: str, **kwargs: Any) -> Any:
+        resp = await self.request(method, url, **kwargs)
+        return self.parse_body(resp)
+
+    async def headers_and_body(
+            self, method: str, url: str, **kwargs: Any) -> Tuple[httpx.Headers, Any]:
+        resp = await self.request(method, url, **kwargs)
+        return resp.headers, self.parse_body(resp)
+
+    def parse_body(self, resp: httpx.Response) -> Any:
+        return resp.json()
+
+    async def aclose(self) -> None:
+        await self._async_client.aclose()