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.

Security Warning

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.

Configuring the manhole

To enable it, first add the manhole listener configuration in your homeserver.yaml. You can find information on how to do that in the configuration manual. The configuration is slightly different if you're using docker.

Docker config

If you are using Docker, set bind_addresses to ['0.0.0.0'] as shown:

listeners:
  - port: 9000
    bind_addresses: ['0.0.0.0']
    type: manhole

When using docker run to start the server, you will then need to change the command to the following to include the manhole port forwarding. The -p 127.0.0.1:9000:9000 below is important: it ensures that access to the manhole is only possible for local users.

docker run -d --name synapse \
    --mount type=volume,src=synapse-data,dst=/data \
    -p 8008:8008 \
    -p 127.0.0.1:9000:9000 \
    vectorim/synapse:latest

Native config

If you are not using docker, set bind_addresses to ['::1', '127.0.0.1'] as shown. The bind_addresses in the example below is important: it ensures that access to the manhole is only possible for local users).

listeners:
  - port: 9000
    bind_addresses: ['::1', '127.0.0.1']
    type: manhole

Security settings

The following config options are available:

username - The username for the manhole (defaults to matrix)
password - The password for the manhole (defaults to rabbithole)
ssh_priv_key - The path to a private SSH key (defaults to a hardcoded value)
ssh_pub_key - The path to a public SSH key (defaults to a hardcoded value)

For example:

manhole_settings:
  username: manhole
  password: mypassword
  ssh_priv_key: "/home/synapse/manhole_keys/id_rsa"
  ssh_pub_key: "/home/synapse/manhole_keys/id_rsa.pub"

Accessing synapse manhole

Then restart synapse, and point an ssh client at port 9000 on localhost, using the username and password configured in homeserver.yaml - with the default configuration, this would be:

ssh -p9000 matrix@localhost

Then enter the password when prompted (the default 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.

Note that, prior to Synapse 1.41, any call which returns a coroutine will need to be wrapped in ensureDeferred.

As a simple example, retrieving an event from the database:

>>> from twisted.internet import defer
>>> defer.ensureDeferred(hs.get_datastores().main.get_event('$1416420717069yeQaw:matrix.org'))
<Deferred at 0x7ff253fc6998 current result: <FrozenEvent event_id='$1416420717069yeQaw:matrix.org', type='m.room.create', state_key=''>>

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