Dendrite

Dendrite is a second-generation Matrix homeserver written in Go. It intends to provide an efficient, simple, reliable and scalable alternative to Synapse:

• Efficient: A small memory footprint with better baseline performance than an out-of-the-box Synapse.
• Simple: packaged as a single binary (monolith mode) with minimal required configuration options.
• Reliable: uses the same test suite as Synapse as well as a brand new Go test suite.
• Scalable: can run on multiple machines and eventually scale to massive homeserver deployments.

As of October 2020, Dendrite has now entered beta which means:

• Dendrite is ready for early adopters. We recommend running in Monolith mode with a Postgres database.
• Dendrite has periodic semver releases. We intend to release new versions as we land significant features.
• Dendrite supports database schema upgrades between releases. This means you should never lose your messages when upgrading Dendrite.
• Breaking changes will not occur on minor releases. This means you can safely upgrade Dendrite without modifying your database or config file.

This does not mean:

• Dendrite is bug-free. It has not yet been battle-tested in the real world and so will be error prone initially.
• All of the CS/Federation APIs are implemented. We are tracking progress via a script called 'Are We Synapse Yet?'.
• Dendrite is ready for massive homeserver deployments. You cannot shard each microservice, only run each one on a different machine.

Currently, we expect Dendrite to function well for small (10s/100s of users) homeserver deployments as well as P2P Matrix nodes in-browser or on mobile devices. In the future, we will be able to scale up to gigantic servers (equivalent to matrix.org) via polylith mode.

Quick start

Requires Go 1.13+ and SQLite3 (Postgres is also supported):

$ git clone https://github.com/matrix-org/dendrite
$ cd dendrite

# generate self-signed certificate and an event signing key for federation
$ go build ./cmd/generate-keys
$ ./generate-keys --private-key matrix_key.pem --tls-cert server.crt --tls-key server.key

# Copy and modify the config file:
# you'll need to set a server name and paths to the keys at the very least, along with setting
# up the database filenames
$ cp dendrite-config.yaml dendrite.yaml

# build and run the server
$ go build ./cmd/dendrite-monolith-server
$ ./dendrite-monolith-server --tls-cert server.crt --tls-key server.key --config dendrite.yaml

Then point your favourite Matrix client at http://localhost:8008. For full installation information, see INSTALL.md. For running in Docker, see build/docker.

Progress

We use a script called Are We Synapse Yet which checks Sytest compliance rates. Sytest is a black-box homeserver test rig with around 900 tests. The script works out how many of these tests are passing on Dendrite and it updates with CI. As of August 2020 we're at around 52% CS API coverage and 65% Federation coverage, though check CI for the latest numbers. In practice, this means you can communicate locally and via federation with Synapse servers such as matrix.org reasonably well. There's a long list of features that are not implemented, notably:

• Receipts
• Push
• Search and Context
• User Directory
• Presence
• Guests

We are prioritising features that will benefit single-user homeservers first (e.g Receipts, E2E) rather than features that massive deployments may be interested in (User Directory, OpenID, Guests, Admin APIs, AS API). This means Dendrite supports amongst others:

• Core room functionality (creating rooms, invites, auth rules)
• Federation in rooms v1-v6
• Backfilling locally and via federation
• Accounts, Profiles and Devices
• Published room lists
• Typing
• Media APIs
• Redaction
• Tagging
• E2E keys and device lists

Contributing

We would be grateful for any help on issues marked as Are We Synapse Yet. These issues all have related Sytests which need to pass in order for the issue to be closed. Once you've written your code, you can quickly run Sytest to ensure that the test names are now passing.

For example, if the test Local device key changes get to remote servers was marked as failing, find the test file (e.g via grep or via the CI log output it's tests/50federation/40devicelists.pl ) then to run Sytest:

docker run --rm --name sytest
-v "/Users/kegan/github/sytest:/sytest"
-v "/Users/kegan/github/dendrite:/src"
-v "/Users/kegan/logs:/logs"
-v "/Users/kegan/go/:/gopath"
-e "POSTGRES=1" -e "DENDRITE_TRACE_HTTP=1"
matrixdotorg/sytest-dendrite:latest tests/50federation/40devicelists.pl

See sytest.md for the full description of these flags.

You can try running sytest outside of docker for faster runs, but the dependencies can be temperamental and we recommend using docker where possible.

cd sytest
export PERL5LIB=$HOME/lib/perl5
export PERL_MB_OPT=--install_base=$HOME
export PERL_MM_OPT=INSTALL_BASE=$HOME
./install-deps.pl

./run-tests.pl -I Dendrite::Monolith -d $PATH_TO_DENDRITE_BINARIES

Sometimes Sytest is testing the wrong thing or is flakey, so it will need to be patched. Ask on #dendrite-dev:matrix.org if you think this is the case for you and we'll be happy to help.

If you're new to the project, see CONTRIBUTING.md to get up to speed then look for Good First Issues. If you're familiar with the project, look for Help Wanted issues.

Hardware requirements

Dendrite in Monolith + SQLite works in a range of environments including iOS and in-browser via WASM.

For small homeserver installations joined on ~10s rooms on matrix.org with ~100s of users in those rooms, including some encrypted rooms:

• Memory: uses around 100MB of RAM, with peaks at around 200MB.
• Disk space: After a few months of usage, the database grew to around 2GB (in Monolith mode).
• CPU: Brief spikes when processing events, typically idles at 1% CPU.

This means Dendrite should comfortably work on things like Raspberry Pis.

Discussion

For questions about Dendrite we have a dedicated room on Matrix #dendrite:matrix.org. Development discussion should happen in #dendrite-dev:matrix.org.