Add a primitive helper script for listing worker endpoints. (#15243)

Co-authored-by: Patrick Cloke <patrickc@matrix.org>

changelog.d/15243.feature

@@ -0,0 +1 @@
+Add a primitive helper script for listing worker endpoints.

synapse/_scripts/generate_workers_map.py

@@ -0,0 +1,302 @@
+#!/usr/bin/env python
+# Copyright 2022-2023 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 argparse
+import logging
+import re
+from collections import defaultdict
+from dataclasses import dataclass
+from typing import Dict, Iterable, Optional, Pattern, Set, Tuple
+
+import yaml
+
+from synapse.config.homeserver import HomeServerConfig
+from synapse.federation.transport.server import (
+    TransportLayerServer,
+    register_servlets as register_federation_servlets,
+)
+from synapse.http.server import HttpServer, ServletCallback
+from synapse.rest import ClientRestResource
+from synapse.rest.key.v2 import RemoteKey
+from synapse.server import HomeServer
+from synapse.storage import DataStore
+
+logger = logging.getLogger("generate_workers_map")
+
+
+class MockHomeserver(HomeServer):
+    DATASTORE_CLASS = DataStore  # type: ignore
+
+    def __init__(self, config: HomeServerConfig, worker_app: Optional[str]) -> None:
+        super().__init__(config.server.server_name, config=config)
+        self.config.worker.worker_app = worker_app
+
+
+GROUP_PATTERN = re.compile(r"\(\?P<[^>]+?>(.+?)\)")
+
+
+@dataclass
+class EndpointDescription:
+    """
+    Describes an endpoint and how it should be routed.
+    """
+
+    # The servlet class that handles this endpoint
+    servlet_class: object
+
+    # The category of this endpoint. Is read from the `CATEGORY` constant in the servlet
+    # class.
+    category: Optional[str]
+
+    # TODO:
+    #  - does it need to be routed based on a stream writer config?
+    #  - does it benefit from any optimised, but optional, routing?
+    #  - what 'opinionated synapse worker class' (event_creator, synchrotron, etc) does
+    #    it go in?
+
+
+class EnumerationResource(HttpServer):
+    """
+    Accepts servlet registrations for the purposes of building up a description of
+    all endpoints.
+    """
+
+    def __init__(self, is_worker: bool) -> None:
+        self.registrations: Dict[Tuple[str, str], EndpointDescription] = {}
+        self._is_worker = is_worker
+
+    def register_paths(
+        self,
+        method: str,
+        path_patterns: Iterable[Pattern],
+        callback: ServletCallback,
+        servlet_classname: str,
+    ) -> None:
+        # federation servlet callbacks are wrapped, so unwrap them.
+        callback = getattr(callback, "__wrapped__", callback)
+
+        # fish out the servlet class
+        servlet_class = callback.__self__.__class__  # type: ignore
+
+        if self._is_worker and method in getattr(
+            servlet_class, "WORKERS_DENIED_METHODS", ()
+        ):
+            # This endpoint would cause an error if called on a worker, so pretend it
+            # was never registered!
+            return
+
+        sd = EndpointDescription(
+            servlet_class=servlet_class,
+            category=getattr(servlet_class, "CATEGORY", None),
+        )
+
+        for pat in path_patterns:
+            self.registrations[(method, pat.pattern)] = sd
+
+
+def get_registered_paths_for_hs(
+    hs: HomeServer,
+) -> Dict[Tuple[str, str], EndpointDescription]:
+    """
+    Given a homeserver, get all registered endpoints and their descriptions.
+    """
+
+    enumerator = EnumerationResource(is_worker=hs.config.worker.worker_app is not None)
+    ClientRestResource.register_servlets(enumerator, hs)
+    federation_server = TransportLayerServer(hs)
+
+    # we can't use `federation_server.register_servlets` but this line does the
+    # same thing, only it uses this enumerator
+    register_federation_servlets(
+        federation_server.hs,
+        resource=enumerator,
+        ratelimiter=federation_server.ratelimiter,
+        authenticator=federation_server.authenticator,
+        servlet_groups=federation_server.servlet_groups,
+    )
+
+    # the key server endpoints are separate again
+    RemoteKey(hs).register(enumerator)
+
+    return enumerator.registrations
+
+
+def get_registered_paths_for_default(
+    worker_app: Optional[str], base_config: HomeServerConfig
+) -> Dict[Tuple[str, str], EndpointDescription]:
+    """
+    Given the name of a worker application and a base homeserver configuration,
+    returns:
+
+        Dict from (method, path) to EndpointDescription
+
+    TODO Don't require passing in a config
+    """
+
+    hs = MockHomeserver(base_config, worker_app)
+    # TODO We only do this to avoid an error, but don't need the database etc
+    hs.setup()
+    return get_registered_paths_for_hs(hs)
+
+
+def elide_http_methods_if_unconflicting(
+    registrations: Dict[Tuple[str, str], EndpointDescription],
+    all_possible_registrations: Dict[Tuple[str, str], EndpointDescription],
+) -> Dict[Tuple[str, str], EndpointDescription]:
+    """
+    Elides HTTP methods (by replacing them with `*`) if all possible registered methods
+    can be handled by the worker whose registration map is `registrations`.
+
+    i.e. the only endpoints left with methods (other than `*`) should be the ones where
+    the worker can't handle all possible methods for that path.
+    """
+
+    def paths_to_methods_dict(
+        methods_and_paths: Iterable[Tuple[str, str]]
+    ) -> Dict[str, Set[str]]:
+        """
+        Given (method, path) pairs, produces a dict from path to set of methods
+        available at that path.
+        """
+        result: Dict[str, Set[str]] = {}
+        for method, path in methods_and_paths:
+            result.setdefault(path, set()).add(method)
+        return result
+
+    all_possible_reg_methods = paths_to_methods_dict(all_possible_registrations)
+    reg_methods = paths_to_methods_dict(registrations)
+
+    output = {}
+
+    for path, handleable_methods in reg_methods.items():
+        if handleable_methods == all_possible_reg_methods[path]:
+            any_method = next(iter(handleable_methods))
+            # TODO This assumes that all methods have the same servlet.
+            #      I suppose that's possibly dubious?
+            output[("*", path)] = registrations[(any_method, path)]
+        else:
+            for method in handleable_methods:
+                output[(method, path)] = registrations[(method, path)]
+
+    return output
+
+
+def simplify_path_regexes(
+    registrations: Dict[Tuple[str, str], EndpointDescription]
+) -> Dict[Tuple[str, str], EndpointDescription]:
+    """
+    Simplify all the path regexes for the dict of endpoint descriptions,
+    so that we don't use the Python-specific regex extensions
+    (and also to remove needlessly specific detail).
+    """
+
+    def simplify_path_regex(path: str) -> str:
+        """
+        Given a regex pattern, replaces all named capturing groups (e.g. `(?P<blah>xyz)`)
+        with a simpler version available in more common regex dialects (e.g. `.*`).
+        """
+
+        # TODO it's hard to choose between these two;
+        #      `.*` is a vague simplification
+        # return GROUP_PATTERN.sub(r"\1", path)
+        return GROUP_PATTERN.sub(r".*", path)
+
+    return {(m, simplify_path_regex(p)): v for (m, p), v in registrations.items()}
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description=(
+            "Updates a synapse database to the latest schema and optionally runs background updates"
+            " on it."
+        )
+    )
+    parser.add_argument("-v", action="store_true")
+    parser.add_argument(
+        "--config-path",
+        type=argparse.FileType("r"),
+        required=True,
+        help="Synapse configuration file",
+    )
+
+    args = parser.parse_args()
+
+    # TODO
+    # logging.basicConfig(**logging_config)
+
+    # Load, process and sanity-check the config.
+    hs_config = yaml.safe_load(args.config_path)
+
+    config = HomeServerConfig()
+    config.parse_config_dict(hs_config, "", "")
+
+    master_paths = get_registered_paths_for_default(None, config)
+    worker_paths = get_registered_paths_for_default(
+        "synapse.app.generic_worker", config
+    )
+
+    all_paths = {**master_paths, **worker_paths}
+
+    elided_worker_paths = elide_http_methods_if_unconflicting(worker_paths, all_paths)
+    elide_http_methods_if_unconflicting(master_paths, all_paths)
+
+    # TODO SSO endpoints (pick_idp etc) NOT REGISTERED BY THIS SCRIPT
+
+    categories_to_methods_and_paths: Dict[
+        Optional[str], Dict[Tuple[str, str], EndpointDescription]
+    ] = defaultdict(dict)
+
+    for (method, path), desc in elided_worker_paths.items():
+        categories_to_methods_and_paths[desc.category][method, path] = desc
+
+    for category, contents in categories_to_methods_and_paths.items():
+        print_category(category, contents)
+
+
+def print_category(
+    category_name: Optional[str],
+    elided_worker_paths: Dict[Tuple[str, str], EndpointDescription],
+) -> None:
+    """
+    Prints out a category, in documentation page style.
+
+    Example:
+    ```
+    # Category name
+    /path/xyz
+
+    GET /path/abc
+    ```
+    """
+
+    if category_name:
+        print(f"# {category_name}")
+    else:
+        print("# (Uncategorised requests)")
+
+    for ln in sorted(
+        p for m, p in simplify_path_regexes(elided_worker_paths) if m == "*"
+    ):
+        print(ln)
+    print()
+    for ln in sorted(
+        f"{m:6} {p}" for m, p in simplify_path_regexes(elided_worker_paths) if m != "*"
+    ):
+        print(ln)
+    print()
+
+
+if __name__ == "__main__":
+    main()

synapse/federation/transport/server/__init__.py

@@ -108,6 +108,7 @@ class PublicRoomList(BaseFederationServlet):
     """
 
     PATH = "/publicRooms"
+    CATEGORY = "Federation requests"
 
     def __init__(
         self,
@@ -212,6 +213,7 @@ class OpenIdUserInfo(BaseFederationServlet):
     """
 
     PATH = "/openid/userinfo"
+    CATEGORY = "Federation requests"
 
     REQUIRE_AUTH = False
 

synapse/federation/transport/server/federation.py

@@ -70,6 +70,7 @@ class BaseFederationServerServlet(BaseFederationServlet):
 
 class FederationSendServlet(BaseFederationServerServlet):
     PATH = "/send/(?P<transaction_id>[^/]*)/?"
+    CATEGORY = "Inbound federation transaction request"
 
     # We ratelimit manually in the handler as we queue up the requests and we
     # don't want to fill up the ratelimiter with blocked requests.
@@ -138,6 +139,7 @@ class FederationSendServlet(BaseFederationServerServlet):
 
 class FederationEventServlet(BaseFederationServerServlet):
     PATH = "/event/(?P<event_id>[^/]*)/?"
+    CATEGORY = "Federation requests"
 
     # This is when someone asks for a data item for a given server data_id pair.
     async def on_GET(
@@ -152,6 +154,7 @@ class FederationEventServlet(BaseFederationServerServlet):
 
 class FederationStateV1Servlet(BaseFederationServerServlet):
     PATH = "/state/(?P<room_id>[^/]*)/?"
+    CATEGORY = "Federation requests"
 
     # This is when someone asks for all data for a given room.
     async def on_GET(
@@ -170,6 +173,7 @@ class FederationStateV1Servlet(BaseFederationServerServlet):
 
 class FederationStateIdsServlet(BaseFederationServerServlet):
     PATH = "/state_ids/(?P<room_id>[^/]*)/?"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -187,6 +191,7 @@ class FederationStateIdsServlet(BaseFederationServerServlet):
 
 class FederationBackfillServlet(BaseFederationServerServlet):
     PATH = "/backfill/(?P<room_id>[^/]*)/?"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -225,6 +230,7 @@ class FederationTimestampLookupServlet(BaseFederationServerServlet):
     """
 
     PATH = "/timestamp_to_event/(?P<room_id>[^/]*)/?"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -246,6 +252,7 @@ class FederationTimestampLookupServlet(BaseFederationServerServlet):
 
 class FederationQueryServlet(BaseFederationServerServlet):
     PATH = "/query/(?P<query_type>[^/]*)"
+    CATEGORY = "Federation requests"
 
     # This is when we receive a server-server Query
     async def on_GET(
@@ -262,6 +269,7 @@ class FederationQueryServlet(BaseFederationServerServlet):
 
 class FederationMakeJoinServlet(BaseFederationServerServlet):
     PATH = "/make_join/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -297,6 +305,7 @@ class FederationMakeJoinServlet(BaseFederationServerServlet):
 
 class FederationMakeLeaveServlet(BaseFederationServerServlet):
     PATH = "/make_leave/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -312,6 +321,7 @@ class FederationMakeLeaveServlet(BaseFederationServerServlet):
 
 class FederationV1SendLeaveServlet(BaseFederationServerServlet):
     PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_PUT(
         self,
@@ -327,6 +337,7 @@ class FederationV1SendLeaveServlet(BaseFederationServerServlet):
 
 class FederationV2SendLeaveServlet(BaseFederationServerServlet):
     PATH = "/send_leave/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     PREFIX = FEDERATION_V2_PREFIX
 
@@ -344,6 +355,7 @@ class FederationV2SendLeaveServlet(BaseFederationServerServlet):
 
 class FederationMakeKnockServlet(BaseFederationServerServlet):
     PATH = "/make_knock/(?P<room_id>[^/]*)/(?P<user_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -366,6 +378,7 @@ class FederationMakeKnockServlet(BaseFederationServerServlet):
 
 class FederationV1SendKnockServlet(BaseFederationServerServlet):
     PATH = "/send_knock/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_PUT(
         self,
@@ -381,6 +394,7 @@ class FederationV1SendKnockServlet(BaseFederationServerServlet):
 
 class FederationEventAuthServlet(BaseFederationServerServlet):
     PATH = "/event_auth/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -395,6 +409,7 @@ class FederationEventAuthServlet(BaseFederationServerServlet):
 
 class FederationV1SendJoinServlet(BaseFederationServerServlet):
     PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_PUT(
         self,
@@ -412,6 +427,7 @@ class FederationV1SendJoinServlet(BaseFederationServerServlet):
 
 class FederationV2SendJoinServlet(BaseFederationServerServlet):
     PATH = "/send_join/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     PREFIX = FEDERATION_V2_PREFIX
 
@@ -455,6 +471,7 @@ class FederationV2SendJoinServlet(BaseFederationServerServlet):
 
 class FederationV1InviteServlet(BaseFederationServerServlet):
     PATH = "/invite/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_PUT(
         self,
@@ -479,6 +496,7 @@ class FederationV1InviteServlet(BaseFederationServerServlet):
 
 class FederationV2InviteServlet(BaseFederationServerServlet):
     PATH = "/invite/(?P<room_id>[^/]*)/(?P<event_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     PREFIX = FEDERATION_V2_PREFIX
 
@@ -515,6 +533,7 @@ class FederationV2InviteServlet(BaseFederationServerServlet):
 
 class FederationThirdPartyInviteExchangeServlet(BaseFederationServerServlet):
     PATH = "/exchange_third_party_invite/(?P<room_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_PUT(
         self,
@@ -529,6 +548,7 @@ class FederationThirdPartyInviteExchangeServlet(BaseFederationServerServlet):
 
 class FederationClientKeysQueryServlet(BaseFederationServerServlet):
     PATH = "/user/keys/query"
+    CATEGORY = "Federation requests"
 
     async def on_POST(
         self, origin: str, content: JsonDict, query: Dict[bytes, List[bytes]]
@@ -538,6 +558,7 @@ class FederationClientKeysQueryServlet(BaseFederationServerServlet):
 
 class FederationUserDevicesQueryServlet(BaseFederationServerServlet):
     PATH = "/user/devices/(?P<user_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_GET(
         self,
@@ -551,6 +572,7 @@ class FederationUserDevicesQueryServlet(BaseFederationServerServlet):
 
 class FederationClientKeysClaimServlet(BaseFederationServerServlet):
     PATH = "/user/keys/claim"
+    CATEGORY = "Federation requests"
 
     async def on_POST(
         self, origin: str, content: JsonDict, query: Dict[bytes, List[bytes]]
@@ -561,6 +583,7 @@ class FederationClientKeysClaimServlet(BaseFederationServerServlet):
 
 class FederationGetMissingEventsServlet(BaseFederationServerServlet):
     PATH = "/get_missing_events/(?P<room_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     async def on_POST(
         self,
@@ -586,6 +609,7 @@ class FederationGetMissingEventsServlet(BaseFederationServerServlet):
 
 class On3pidBindServlet(BaseFederationServerServlet):
     PATH = "/3pid/onbind"
+    CATEGORY = "Federation requests"
 
     REQUIRE_AUTH = False
 
@@ -618,6 +642,7 @@ class On3pidBindServlet(BaseFederationServerServlet):
 
 class FederationVersionServlet(BaseFederationServlet):
     PATH = "/version"
+    CATEGORY = "Federation requests"
 
     REQUIRE_AUTH = False
 
@@ -640,6 +665,7 @@ class FederationVersionServlet(BaseFederationServlet):
 
 class FederationRoomHierarchyServlet(BaseFederationServlet):
     PATH = "/hierarchy/(?P<room_id>[^/]*)"
+    CATEGORY = "Federation requests"
 
     def __init__(
         self,
@@ -672,6 +698,7 @@ class RoomComplexityServlet(BaseFederationServlet):
 
     PATH = "/rooms/(?P<room_id>[^/]*)/complexity"
     PREFIX = FEDERATION_UNSTABLE_PREFIX
+    CATEGORY = "Federation requests (unstable)"
 
     def __init__(
         self,

synapse/rest/client/_base.py

@@ -43,19 +43,22 @@ def client_patterns(
     Returns:
         An iterable of patterns.
     """
-    patterns = []
+    versions = []
 
-    if unstable:
-        unstable_prefix = CLIENT_API_PREFIX + "/unstable"
-        patterns.append(re.compile("^" + unstable_prefix + path_regex))
     if v1:
-        v1_prefix = CLIENT_API_PREFIX + "/api/v1"
-        patterns.append(re.compile("^" + v1_prefix + path_regex))
-    for release in releases:
-        new_prefix = CLIENT_API_PREFIX + f"/{release}"
-        patterns.append(re.compile("^" + new_prefix + path_regex))
+        versions.append("api/v1")
+    versions.extend(releases)
+    if unstable:
+        versions.append("unstable")
+
+    if len(versions) == 1:
+        versions_str = versions[0]
+    elif len(versions) > 1:
+        versions_str = "(" + "|".join(versions) + ")"
+    else:
+        raise RuntimeError("Must have at least one version for a URL")
 
-    return patterns
+    return [re.compile("^" + CLIENT_API_PREFIX + "/" + versions_str + path_regex)]
 
 
 def set_timeline_upper_limit(filter_json: JsonDict, filter_timeline_limit: int) -> None:

synapse/rest/client/account.py

@@ -576,6 +576,9 @@ class AddThreepidMsisdnSubmitTokenServlet(RestServlet):
 
 class ThreepidRestServlet(RestServlet):
     PATTERNS = client_patterns("/account/3pid$")
+    # This is used as a proxy for all the 3pid endpoints.
+
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -834,6 +837,7 @@ def assert_valid_next_link(hs: "HomeServer", next_link: str) -> None:
 
 class WhoamiRestServlet(RestServlet):
     PATTERNS = client_patterns("/account/whoami$")
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/account_data.py

@@ -38,6 +38,7 @@ class AccountDataServlet(RestServlet):
     PATTERNS = client_patterns(
         "/user/(?P<user_id>[^/]*)/account_data/(?P<account_data_type>[^/]*)"
     )
+    CATEGORY = "Account data requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -136,6 +137,7 @@ class RoomAccountDataServlet(RestServlet):
         "/rooms/(?P<room_id>[^/]*)"
         "/account_data/(?P<account_data_type>[^/]*)"
     )
+    CATEGORY = "Account data requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/devices.py

@@ -40,6 +40,7 @@ logger = logging.getLogger(__name__)
 
 class DevicesRestServlet(RestServlet):
     PATTERNS = client_patterns("/devices$")
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -123,6 +124,7 @@ class DeleteDevicesRestServlet(RestServlet):
 
 class DeviceRestServlet(RestServlet):
     PATTERNS = client_patterns("/devices/(?P<device_id>[^/]*)$")
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/events.py

@@ -33,6 +33,7 @@ logger = logging.getLogger(__name__)
 
 class EventStreamRestServlet(RestServlet):
     PATTERNS = client_patterns("/events$", v1=True)
+    CATEGORY = "Sync requests"
 
     DEFAULT_LONGPOLL_TIME_MS = 30000
 
@@ -76,6 +77,7 @@ class EventStreamRestServlet(RestServlet):
 
 class EventRestServlet(RestServlet):
     PATTERNS = client_patterns("/events/(?P<event_id>[^/]*)$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/filter.py

@@ -31,6 +31,7 @@ logger = logging.getLogger(__name__)
 
 class GetFilterRestServlet(RestServlet):
     PATTERNS = client_patterns("/user/(?P<user_id>[^/]*)/filter/(?P<filter_id>[^/]*)")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -69,6 +70,7 @@ class GetFilterRestServlet(RestServlet):
 
 class CreateFilterRestServlet(RestServlet):
     PATTERNS = client_patterns("/user/(?P<user_id>[^/]*)/filter")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/initial_sync.py

@@ -28,6 +28,7 @@ if TYPE_CHECKING:
 # TODO: Needs unit testing
 class InitialSyncRestServlet(RestServlet):
     PATTERNS = client_patterns("/initialSync$", v1=True)
+    CATEGORY = "Sync requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/keys.py

@@ -89,6 +89,7 @@ class KeyUploadServlet(RestServlet):
     """
 
     PATTERNS = client_patterns("/keys/upload(/(?P<device_id>[^/]+))?$")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -182,6 +183,7 @@ class KeyQueryServlet(RestServlet):
     """
 
     PATTERNS = client_patterns("/keys/query$")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -225,6 +227,7 @@ class KeyChangesServlet(RestServlet):
     """
 
     PATTERNS = client_patterns("/keys/changes$")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -274,6 +277,7 @@ class OneTimeKeyServlet(RestServlet):
     """
 
     PATTERNS = client_patterns("/keys/claim$")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/knock.py

@@ -40,6 +40,7 @@ class KnockRoomAliasServlet(RestServlet):
     """
 
     PATTERNS = client_patterns("/knock/(?P<room_identifier>[^/]*)")
+    CATEGORY = "Event sending requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/login.py

@@ -72,6 +72,8 @@ class LoginResponse(TypedDict, total=False):
 
 class LoginRestServlet(RestServlet):
     PATTERNS = client_patterns("/login$", v1=True)
+    CATEGORY = "Registration/login requests"
+
     CAS_TYPE = "m.login.cas"
     SSO_TYPE = "m.login.sso"
     TOKEN_TYPE = "m.login.token"
@@ -537,6 +539,7 @@ def _get_auth_flow_dict_for_idp(idp: SsoIdentityProvider) -> JsonDict:
 
 class RefreshTokenServlet(RestServlet):
     PATTERNS = client_patterns("/refresh$")
+    CATEGORY = "Registration/login requests"
 
     def __init__(self, hs: "HomeServer"):
         self._auth_handler = hs.get_auth_handler()
@@ -590,6 +593,7 @@ class SsoRedirectServlet(RestServlet):
             + "/(r0|v3)/login/sso/redirect/(?P<idp_id>[A-Za-z0-9_.~-]+)$"
         )
     ]
+    CATEGORY = "SSO requests needed for all SSO providers"
 
     def __init__(self, hs: "HomeServer"):
         # make sure that the relevant handlers are instantiated, so that they

synapse/rest/client/presence.py

@@ -33,6 +33,7 @@ logger = logging.getLogger(__name__)
 
 class PresenceStatusRestServlet(RestServlet):
     PATTERNS = client_patterns("/presence/(?P<user_id>[^/]*)/status", v1=True)
+    CATEGORY = "Presence requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/profile.py

@@ -29,6 +29,7 @@ if TYPE_CHECKING:
 
 class ProfileDisplaynameRestServlet(RestServlet):
     PATTERNS = client_patterns("/profile/(?P<user_id>[^/]*)/displayname", v1=True)
+    CATEGORY = "Event sending requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -86,6 +87,7 @@ class ProfileDisplaynameRestServlet(RestServlet):
 
 class ProfileAvatarURLRestServlet(RestServlet):
     PATTERNS = client_patterns("/profile/(?P<user_id>[^/]*)/avatar_url", v1=True)
+    CATEGORY = "Event sending requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -142,6 +144,7 @@ class ProfileAvatarURLRestServlet(RestServlet):
 
 class ProfileRestServlet(RestServlet):
     PATTERNS = client_patterns("/profile/(?P<user_id>[^/]*)", v1=True)
+    CATEGORY = "Event sending requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/push_rule.py

@@ -44,6 +44,9 @@ class PushRuleRestServlet(RestServlet):
         "Unrecognised request: You probably wanted a trailing slash"
     )
 
+    WORKERS_DENIED_METHODS = ["PUT", "DELETE"]
+    CATEGORY = "Push rule requests"
+
     def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.auth = hs.get_auth()

synapse/rest/client/read_marker.py

@@ -31,6 +31,7 @@ logger = logging.getLogger(__name__)
 
 class ReadMarkerRestServlet(RestServlet):
     PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/read_markers$")
+    CATEGORY = "Receipts requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/receipts.py

@@ -36,6 +36,7 @@ class ReceiptRestServlet(RestServlet):
         "/receipt/(?P<receipt_type>[^/]*)"
         "/(?P<event_id>[^/]*)$"
     )
+    CATEGORY = "Receipts requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/register.py

@@ -367,6 +367,7 @@ class RegistrationTokenValidityRestServlet(RestServlet):
         f"/register/{LoginType.REGISTRATION_TOKEN}/validity",
         releases=("v1",),
     )
+    CATEGORY = "Registration/login requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -395,6 +396,7 @@ class RegistrationTokenValidityRestServlet(RestServlet):
 
 class RegisterRestServlet(RestServlet):
     PATTERNS = client_patterns("/register$")
+    CATEGORY = "Registration/login requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/relations.py

@@ -42,6 +42,7 @@ class RelationPaginationServlet(RestServlet):
         "(/(?P<relation_type>[^/]*)(/(?P<event_type>[^/]*))?)?$",
         releases=("v1",),
     )
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -84,6 +85,7 @@ class RelationPaginationServlet(RestServlet):
 
 class ThreadsServlet(RestServlet):
     PATTERNS = (re.compile("^/_matrix/client/v1/rooms/(?P<room_id>[^/]*)/threads"),)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/room.py

@@ -140,7 +140,7 @@ class TransactionRestServlet(RestServlet):
 
 
 class RoomCreateRestServlet(TransactionRestServlet):
-    # No PATTERN; we have custom dispatch rules here
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
@@ -180,6 +180,8 @@ class RoomCreateRestServlet(TransactionRestServlet):
 
 # TODO: Needs unit testing for generic events
 class RoomStateEventRestServlet(RestServlet):
+    CATEGORY = "Event sending requests"
+
     def __init__(self, hs: "HomeServer"):
         super().__init__()
         self.event_creation_handler = hs.get_event_creation_handler()
@@ -323,6 +325,8 @@ class RoomStateEventRestServlet(RestServlet):
 
 # TODO: Needs unit testing for generic events + feedback
 class RoomSendEventRestServlet(TransactionRestServlet):
+    CATEGORY = "Event sending requests"
+
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
         self.event_creation_handler = hs.get_event_creation_handler()
@@ -398,6 +402,8 @@ class RoomSendEventRestServlet(TransactionRestServlet):
 
 # TODO: Needs unit testing for room ID + alias joins
 class JoinRoomAliasServlet(ResolveRoomIdMixin, TransactionRestServlet):
+    CATEGORY = "Event sending requests"
+
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
         super(ResolveRoomIdMixin, self).__init__(hs)  # ensure the Mixin is set up
@@ -460,6 +466,7 @@ class JoinRoomAliasServlet(ResolveRoomIdMixin, TransactionRestServlet):
 # TODO: Needs unit testing
 class PublicRoomListRestServlet(RestServlet):
     PATTERNS = client_patterns("/publicRooms$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -578,6 +585,7 @@ class PublicRoomListRestServlet(RestServlet):
 # TODO: Needs unit testing
 class RoomMemberListRestServlet(RestServlet):
     PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/members$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -633,6 +641,7 @@ class RoomMemberListRestServlet(RestServlet):
 # except it does custom AS logic and has a simpler return format
 class JoinedRoomMemberListRestServlet(RestServlet):
     PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/joined_members$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -654,6 +663,10 @@ class JoinedRoomMemberListRestServlet(RestServlet):
 # TODO: Needs better unit testing
 class RoomMessageListRestServlet(RestServlet):
     PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/messages$", v1=True)
+    # TODO The routing information should be exposed programatically.
+    #      I want to do this but for now I felt bad about leaving this without
+    #      at least a visible warning on it.
+    CATEGORY = "Client API requests (ALL FOR SAME ROOM MUST GO TO SAME WORKER)"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -720,6 +733,7 @@ class RoomMessageListRestServlet(RestServlet):
 # TODO: Needs unit testing
 class RoomStateRestServlet(RestServlet):
     PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/state$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -742,6 +756,7 @@ class RoomStateRestServlet(RestServlet):
 # TODO: Needs unit testing
 class RoomInitialSyncRestServlet(RestServlet):
     PATTERNS = client_patterns("/rooms/(?P<room_id>[^/]*)/initialSync$", v1=True)
+    CATEGORY = "Sync requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -766,6 +781,7 @@ class RoomEventServlet(RestServlet):
     PATTERNS = client_patterns(
         "/rooms/(?P<room_id>[^/]*)/event/(?P<event_id>[^/]*)$", v1=True
     )
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -858,6 +874,7 @@ class RoomEventContextServlet(RestServlet):
     PATTERNS = client_patterns(
         "/rooms/(?P<room_id>[^/]*)/context/(?P<event_id>[^/]*)$", v1=True
     )
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -958,6 +975,8 @@ class RoomForgetRestServlet(TransactionRestServlet):
 
 # TODO: Needs unit testing
 class RoomMembershipRestServlet(TransactionRestServlet):
+    CATEGORY = "Event sending requests"
+
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
         self.room_member_handler = hs.get_room_member_handler()
@@ -1071,6 +1090,8 @@ class RoomMembershipRestServlet(TransactionRestServlet):
 
 
 class RoomRedactEventRestServlet(TransactionRestServlet):
+    CATEGORY = "Event sending requests"
+
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)
         self.event_creation_handler = hs.get_event_creation_handler()
@@ -1164,6 +1185,7 @@ class RoomTypingRestServlet(RestServlet):
     PATTERNS = client_patterns(
         "/rooms/(?P<room_id>[^/]*)/typing/(?P<user_id>[^/]*)$", v1=True
     )
+    CATEGORY = "The typing stream"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1195,7 +1217,7 @@ class RoomTypingRestServlet(RestServlet):
         # Limit timeout to stop people from setting silly typing timeouts.
         timeout = min(content.get("timeout", 30000), 120000)
 
-        # Defer getting the typing handler since it will raise on workers.
+        # Defer getting the typing handler since it will raise on WORKER_PATTERNS.
         typing_handler = self.hs.get_typing_writer_handler()
 
         try:
@@ -1224,6 +1246,7 @@ class RoomAliasListServlet(RestServlet):
             r"/rooms/(?P<room_id>[^/]*)/aliases"
         ),
     ] + list(client_patterns("/rooms/(?P<room_id>[^/]*)/aliases$", unstable=False))
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1244,6 +1267,7 @@ class RoomAliasListServlet(RestServlet):
 
 class SearchRestServlet(RestServlet):
     PATTERNS = client_patterns("/search$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1263,6 +1287,7 @@ class SearchRestServlet(RestServlet):
 
 class JoinedRoomsRestServlet(RestServlet):
     PATTERNS = client_patterns("/joined_rooms$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1334,6 +1359,7 @@ class TimestampLookupRestServlet(RestServlet):
     PATTERNS = (
         re.compile("^/_matrix/client/v1/rooms/(?P<room_id>[^/]*)/timestamp_to_event$"),
     )
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1365,6 +1391,8 @@ class TimestampLookupRestServlet(RestServlet):
 
 class RoomHierarchyRestServlet(RestServlet):
     PATTERNS = (re.compile("^/_matrix/client/v1/rooms/(?P<room_id>[^/]*)/hierarchy$"),)
+    WORKERS = PATTERNS
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -1405,6 +1433,7 @@ class RoomSummaryRestServlet(ResolveRoomIdMixin, RestServlet):
             "/rooms/(?P<room_identifier>[^/]*)/summary$"
         ),
     )
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__(hs)

synapse/rest/client/room_batch.py

@@ -69,6 +69,7 @@ class RoomBatchSendEventRestServlet(RestServlet):
             "/rooms/(?P<room_id>[^/]*)/batch_send$"
         ),
     )
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/room_keys.py

@@ -37,6 +37,7 @@ class RoomKeysServlet(RestServlet):
     PATTERNS = client_patterns(
         "/room_keys/keys(/(?P<room_id>[^/]+))?(/(?P<session_id>[^/]+))?$"
     )
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -253,6 +254,7 @@ class RoomKeysServlet(RestServlet):
 
 class RoomKeysNewVersionServlet(RestServlet):
     PATTERNS = client_patterns("/room_keys/version$")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -328,6 +330,7 @@ class RoomKeysNewVersionServlet(RestServlet):
 
 class RoomKeysVersionServlet(RestServlet):
     PATTERNS = client_patterns("/room_keys/version/(?P<version>[^/]+)$")
+    CATEGORY = "Encryption requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/sendtodevice.py

@@ -35,6 +35,7 @@ class SendToDeviceRestServlet(servlet.RestServlet):
     PATTERNS = client_patterns(
         "/sendToDevice/(?P<message_type>[^/]*)/(?P<txn_id>[^/]*)$"
     )
+    CATEGORY = "The to_device stream"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/sync.py

@@ -87,6 +87,7 @@ class SyncRestServlet(RestServlet):
 
     PATTERNS = client_patterns("/sync$")
     ALLOWED_PRESENCE = {"online", "offline", "unavailable"}
+    CATEGORY = "Sync requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/tags.py

@@ -37,6 +37,7 @@ class TagListServlet(RestServlet):
     PATTERNS = client_patterns(
         "/user/(?P<user_id>[^/]*)/rooms/(?P<room_id>[^/]*)/tags$"
     )
+    CATEGORY = "Account data requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()
@@ -64,6 +65,7 @@ class TagServlet(RestServlet):
     PATTERNS = client_patterns(
         "/user/(?P<user_id>[^/]*)/rooms/(?P<room_id>[^/]*)/tags/(?P<tag>[^/]*)"
     )
+    CATEGORY = "Account data requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/user_directory.py

@@ -31,6 +31,7 @@ logger = logging.getLogger(__name__)
 
 class UserDirectorySearchRestServlet(RestServlet):
     PATTERNS = client_patterns("/user_directory/search$")
+    CATEGORY = "User directory search requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/versions.py

@@ -34,6 +34,7 @@ logger = logging.getLogger(__name__)
 
 class VersionsRestServlet(RestServlet):
     PATTERNS = [re.compile("^/_matrix/client/versions$")]
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/client/voip.py

@@ -29,6 +29,7 @@ if TYPE_CHECKING:
 
 class VoipRestServlet(RestServlet):
     PATTERNS = client_patterns("/voip/turnServer$", v1=True)
+    CATEGORY = "Client API requests"
 
     def __init__(self, hs: "HomeServer"):
         super().__init__()

synapse/rest/key/v2/remote_key_resource.py

@@ -93,6 +93,8 @@ class RemoteKey(RestServlet):
     }
     """
 
+    CATEGORY = "Federation requests"
+
     def __init__(self, hs: "HomeServer"):
         self.fetcher = ServerKeyFetcher(hs)
         self.store = hs.get_datastores().main