Notes on the manhole

docs/manhole.md

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+Using the synapse manhole
+=========================
+
+The "manhole" allows server administrators to access a Python shell on a running
+Synapse installation. This is a very powerful mechanism for administration and
+debugging.
+
+To enable it, first uncomment the `manhole` listener configuration in
+`homeserver.yaml`:
+
+```yaml
+listeners:
+  - port: 9000
+    bind_addresses: ['::1', '127.0.0.1']
+    type: manhole
+```
+
+(`bind_addresses` in the above is important: it ensures that access to the
+manhole is only possible for local users).
+
+Note that this will give administrative access to synapse to **all users** with
+shell access to the server. It should therefore **not** be enabled in
+environments where untrusted users have shell access.
+
+Then restart synapse, and point an ssh client at port 9000 on localhost, using
+the username `matrix`:
+
+```bash
+ssh -p9000 matrix@localhost
+```
+
+The password is `rabbithole`.
+
+This gives a Python REPL in which `hs` gives access to the
+`synapse.server.HomeServer` object - which in turn gives access to many other
+parts of the process.
+
+As a simple example, retrieving an event from the database:
+
+```
+>>> hs.get_datastore().get_event('$1416420717069yeQaw:matrix.org')
+<Deferred at 0x7ff253fc6998 current result: <FrozenEvent event_id='$1416420717069yeQaw:matrix.org', type='m.room.create', state_key=''>>
+```