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Multiple Dendrite instances

26 December 2022 — ~ideclon

Hosting multiple Dendrite instances on one server

As mentioned in my previous post, I’m running Dendrite as my Matrix homeserver.

As well as my ideclon.uk Matrix instance, I’m running other instances of Dendrite in the same VM for other purposes. Each of these instances are running as a separate SystemD service.

Here’s the basics of setting up another Dendrite instance on a server already running one.

Notes

  • Note that I am not using Docker.

  • You'll notice that I'm not using SSL here. SSL is being added by a Traefik proxy. If you're not using a reverse proxy, use -https-bind-address instead.

  • If you are using HTTPS, the default port is 8448, not 8008. (8008 is the default HTTP port, 8448 is the default HTTPS port).

Configuration

Each instance will need it’s own config file and storage directory. I’m using /etc/dendrite/[DOMAIN].

Config file

You can just copy the default config file and replace:

  • server_name

  • private_key

  • database -> connection_string

private_key is the Matrix signing key you’ll generate below.

For the connection_string, you just need to replace the database name.

Ports

Dendrite listens on port 8008 on all interfaces by default. You can override this with the CLI flag --http-bind-address. Multiple Dendrite instances won’t be able to listen on the same interface/port combo, so you could have Dendrite listen on a different port (as I do - 8008, 8018, 8028…), or on the same port on different IPs (if you have them).

As mentioned in my previous post, other Matrix servers (and clients) will expect to find your server on port 8448. You can deal with this via delegation (see that post), or run a proxy server like Traefik in front of your server and forward based on hostnames.

Keys

Generate a new Matrix signing key: $ ./bin/generate-keys --private-key [NEW_KEY_NAME].pem

Database

Each instance will need it’s own database. Assuming you’re using PostgreSQL (as is recommended in the docs), you can just run $ sudo -u postgres createdb -O dendrite -E UTF-8 dendrite_[DOMAIN] to create a new database called dendrite_[DOMAIN], owned by the dendrite role.

SSL / TLS

As mentioned above, this post assumes you’ve set up a Dendrite server before (on the same server you’ll be running this one). This is not a guide on setting up / configuring Matrix. I’m just going to point to the docs on this.

SystemD service

The SystemD service broadly needs to do the following:

  • Run as dendrite:dendrite

  • Run in your new storage directory

  • Run after network-online.target and postgres.service.

Here’s an example:

[Unit]
Description=[DOMAIN] Dendrite (Matrix Homeserver)
After=syslog.target
After=network-online.target
After=postgresql.service

[Service]
Environment=GODEBUG=madvdontneed=1
RestartSec=2s
Type=simple
User=dendrite
Group=dendrite
WorkingDirectory=/etc/dendrite/[DOMAIN]/
ExecStart=/usr/local/bin/dendrite-monolith-server -config /etc/dendrite/[DOMAIN]/dendrite.monolith.yml –http-bind-address :[PORT]
Restart=always
LimitNOFILE=65535

[Install]
WantedBy=multi-user.target

CLI Administration

When running the ./bin/create-account binary, you’ll need to make sure to point it at the correct config file - so -config /etc/dendrite/[DOMAIN]/dendrite.monolith.yml.

And I think that’s it!

Please do let me know if this helped you, or if there’s anything I got wrong.

Mastodon: @ideclon@tilde.zone Matrix: @me:ideclon.uk

tags: matrix, dendrite, systemd, self-hosting, proxy-server