Add admin API to get some information about federation status

changelog.d/11407.feature

@@ -0,0 +1 @@
+Add admin API to get some information about federation status with remote servers.

docs/SUMMARY.md

@@ -64,6 +64,7 @@
       - [Statistics](admin_api/statistics.md)
       - [Users](admin_api/user_admin_api.md)
       - [Server Version](admin_api/version_api.md)
+      - [Federation](usage/administration/admin_api/federation.md)
     - [Manhole](manhole.md)
     - [Monitoring](metrics-howto.md)
     - [Request log format](usage/administration/request_log.md)

docs/usage/administration/admin_api/federation.md

@@ -0,0 +1,81 @@
+# Federation API
+
+This API allows a server administrator to manage Synapse's federation with other homeservers.
+
+Note: This API is new, experimental and "subject to change".
+
+## List of destinations
+
+This API gets the current destination retry timing info for a remote server.
+
+The API is:
+
+A standard request with no filtering:
+
+```
+GET /_synapse/admin/v1/federation/destinations
+```
+
+A response body like the following is returned:
+
+```json
+{
+   "destinations":[
+      {
+         "destination": "matrix.org",
+         "retry_last_ts": 1557332397936,
+         "retry_interval": 3000000,
+         "failure_ts": 1557329397936,
+         "last_successful_stream_ordering": null
+      }
+   ],
+   "total": 1
+}
+```
+
+To paginate, check for `next_token` and if present, call the endpoint again
+with `from` set to the value of `next_token`. This will return a new page.
+
+If the endpoint does not return a `next_token` then there are no more destinations
+to paginate through.
+
+**Parameters**
+
+The following query parameters are available:
+
+- `from` - Offset in the returned list. Defaults to `0`.
+- `limit` - Maximum amount of destinations to return. Defaults to `100`.
+- `order_by` - The method in which to sort the returned list of destinations.
+  Valid values are:
+  - `destination` - Destinations are ordered alphabetically by remote server name.
+    This is the default.
+  - `retry_last_ts` - Destinations are ordered by time of last retry attempt in ms.
+  - `retry_interval` - Destinations are ordered by how long until next retry in ms.
+  - `failure_ts` - Destinations are ordered by when the server started failing in ms.
+  - `last_successful_stream_ordering` - Destinations are ordered by the stream ordering
+    of the most recent successfully-sent PDU.
+- `dir` - Direction of room order. Either `f` for forwards or `b` for backwards. Setting
+  this value to `b` will reverse the above sort order. Defaults to `f`.
+
+*Caution:* The database only has an index on the column `destination`.
+This means that if a different sort order is used,
+this can cause a large load on the database, especially for large environments.
+
+**Response**
+
+The following fields are returned in the JSON response body:
+
+- `destinations` - An array of objects, each containing information about a destination.
+  Destinations objects contain the following fields:
+  - `destination` - string - Name of the remote server to federate.
+  - `retry_last_ts` - integer - The last time Synapse tried and failed to reach the
+    remote server, in ms.
+  - `retry_interval` - integer - How long since the last time Synapse tried to reach
+    the remote server before trying again, in ms.
+  - `failure_ts` - integer - The first time Synapse tried and failed to reach the
+    remote server, in ms.
+  - `last_successful_stream_ordering` - integer - The stream ordering of the most
+    recent successfully-sent [PDU](Understanding-Synapse-Performance-Issues-Through-Grafana-Graphs.md#federation)
+    to this destination or `null` if this information has not been tracked yet.
+- `next_token`: string representing a positive integer - Indication for pagination. See above.
+- `total` - integer - Total number of destinations.

synapse/rest/admin/__init__.py

@@ -39,6 +39,7 @@
     EventReportDetailRestServlet,
     EventReportsRestServlet,
 )
+from synapse.rest.admin.federation import FederationDestinationRestServlet
 from synapse.rest.admin.groups import DeleteGroupAdminRestServlet
 from synapse.rest.admin.media import ListMediaInRoom, register_servlets_for_media_repo
 from synapse.rest.admin.registration_tokens import (
@@ -256,6 +257,7 @@ def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
     ListRegistrationTokensRestServlet(hs).register(http_server)
     NewRegistrationTokenRestServlet(hs).register(http_server)
     RegistrationTokenRestServlet(hs).register(http_server)
+    FederationDestinationRestServlet(hs).register(http_server)
 
     # Some servlets only get registered for the main process.
     if hs.config.worker.worker_app is None:

synapse/rest/admin/federation.py

@@ -0,0 +1,90 @@
+# Copyright 2021 The Matrix.org Foundation C.I.C.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import logging
+from http import HTTPStatus
+from typing import TYPE_CHECKING, Tuple
+
+from synapse.api.errors import Codes, SynapseError
+from synapse.http.servlet import RestServlet, parse_integer, parse_string
+from synapse.http.site import SynapseRequest
+from synapse.rest.admin._base import admin_patterns, assert_requester_is_admin
+from synapse.storage.databases.main.transactions import DestinationSortOrder
+from synapse.types import JsonDict
+
+if TYPE_CHECKING:
+    from synapse.server import HomeServer
+
+logger = logging.getLogger(__name__)
+
+
+class FederationDestinationRestServlet(RestServlet):
+    """Get request to list all destinations.
+    This needs user to have administrator access in Synapse.
+
+    GET /_synapse/admin/v1/federation/destinations?from=0&limit=10
+
+    returns:
+        200 OK with list of destinations if success otherwise an error.
+
+    The parameters `from` and `limit` are required only for pagination.
+    By default, a `limit` of 100 is used.
+    The parameter `destination` can be used to filter by destination.
+    The parameter `order_by` can be used to order the result.
+    """
+
+    PATTERNS = admin_patterns("/federation/destinations$")
+
+    def __init__(self, hs: "HomeServer"):
+        self._auth = hs.get_auth()
+        self._store = hs.get_datastore()
+
+    async def on_GET(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
+        await assert_requester_is_admin(self._auth, request)
+
+        start = parse_integer(request, "from", default=0)
+        limit = parse_integer(request, "limit", default=100)
+
+        if start < 0:
+            raise SynapseError(
+                HTTPStatus.BAD_REQUEST,
+                "Query parameter from must be a string representing a positive integer.",
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        if limit < 0:
+            raise SynapseError(
+                HTTPStatus.BAD_REQUEST,
+                "Query parameter limit must be a string representing a positive integer.",
+                errcode=Codes.INVALID_PARAM,
+            )
+
+        destination = parse_string(request, "destination")
+
+        order_by = parse_string(
+            request,
+            "order_by",
+            default=DestinationSortOrder.DESTINATION.value,
+            allowed_values=[dest.value for dest in DestinationSortOrder],
+        )
+
+        direction = parse_string(request, "dir", default="f", allowed_values=("f", "b"))
+
+        destinations, total = await self._store.get_destinations_paginate(
+            start, limit, destination, order_by, direction
+        )
+        response = {"destinations": destinations, "total": total}
+        if (start + limit) < total:
+            response["next_token"] = str(start + len(destinations))
+
+        return HTTPStatus.OK, response

synapse/storage/databases/main/transactions.py

@@ -14,6 +14,7 @@
 
 import logging
 from collections import namedtuple
+from enum import Enum
 from typing import TYPE_CHECKING, Iterable, List, Optional, Tuple
 
 import attr
@@ -44,6 +45,16 @@
 )
 
 
+class DestinationSortOrder(Enum):
+    """Enum to define the sorting method used when returning destinations."""
+
+    DESTINATION = "destination"
+    RETRY_LAST_TS = "retry_last_ts"
+    RETTRY_INTERVAL = "retry_interval"
+    FAILURE_TS = "failure_ts"
+    LAST_SUCCESSFUL_STREAM_ORDERING = "last_successful_stream_ordering"
+
+
 @attr.s(slots=True, frozen=True, auto_attribs=True)
 class DestinationRetryTimings:
     """The current destination retry timing info for a remote server."""
@@ -480,3 +491,62 @@ def _get_catch_up_outstanding_destinations_txn(
 
         destinations = [row[0] for row in txn]
         return destinations
+
+    async def get_destinations_paginate(
+        self,
+        start: int,
+        limit: int,
+        destination: Optional[str] = None,
+        order_by: str = DestinationSortOrder.DESTINATION.value,
+        direction: str = "f",
+    ) -> Tuple[List[JsonDict], int]:
+        """Function to retrieve a paginated list of destinations.
+        This will return a json list of destinations and the
+        total number of destinations matching the filter criteria.
+
+        Args:
+            start: start number to begin the query from
+            limit: number of rows to retrieve
+            destination: search string in destination
+            order_by: the sort order of the returned list
+            direction: sort ascending or descending
+        Returns:
+            A tuple of a list of mappings from destination to information
+            and a count of total destinations.
+        """
+
+        def get_destinations_paginate_txn(
+            txn: LoggingTransaction,
+        ) -> Tuple[List[JsonDict], int]:
+            order_by_column = DestinationSortOrder(order_by).value
+
+            if direction == "b":
+                order = "DESC"
+            else:
+                order = "ASC"
+
+            args = []
+            where_statement = ""
+            if destination:
+                args.extend(["%" + destination.lower() + "%"])
+                where_statement = "WHERE LOWER(destination) LIKE ?"
+
+            sql_base = f"FROM destinations {where_statement} "
+            sql = f"SELECT COUNT(*) as total_destinations {sql_base}"
+            txn.execute(sql, args)
+            count = txn.fetchone()[0]
+
+            sql = f"""
+                SELECT destination, retry_last_ts, retry_interval, failure_ts,
+                last_successful_stream_ordering
+                {sql_base}
+                ORDER BY {order_by_column} {order}, destination ASC
+                LIMIT ? OFFSET ?
+            """
+            txn.execute(sql, args + [limit, start])
+            destinations = self.db_pool.cursor_to_dict(txn)
+            return destinations, count
+
+        return await self.db_pool.runInteraction(
+            "get_destinations_paginate_txn", get_destinations_paginate_txn
+        )