Mastodon Streaming Server

A WIP blazingly fast drop-in replacement for the Mastodon streaming api server.

Current status

The streaming server is currently a work in progress. However, it is now testable and, if configured properly, would theoretically be usable in production—though production use is not advisable until we have completed further testing. I would greatly appreciate any testing, bug reports, or other feedback you could provide.

Installation

Installing the WIP version requires the Rust toolchain (the released version will be available as a pre-compiled binary). To install, clone this repository and run cargo build (to build the server) cargo run (to both build and run the server), or cargo build --release (to build the server with release optimizations).

Connection to Mastodon

The streaming server expects to connect to a running development version of Mastodon built off of the master branch. Specifically, it needs to connect to both the Postgres database (to authenticate users) and to the Redis database. You should run Mastodon in whatever way you normally do and configure the streaming server to connect to the appropriate databases.

Configuring

You may edit the configuration variables in the config.rs module. You can also overwrite the default config variables in the .env file. Note that, by default, this server is configured to run on port 4000. This allows for easy testing with the development version of Mastodon (which, by default, is configured to communicate with a streaming server running on localhost:4000). However, it also conflicts with the current/Node.js version of Mastodon's streaming server, which runs on the same port. Thus, to test this server, you should disable the Node streaming server or move it to a non-conflicting port.

Documentation

Build documentation with cargo doc --open, which will build the Markdown docs and open them in your browser. Please consult those docs for a detailed description of the code structure/organization. The documentation also contains additional notes about data flow and options for configuration.

Running

As noted above, you can run the server with cargo run. Alternatively, if you built the sever using cargo build or cargo build --release, you can run the executable produced in the target/build/debug folder or the target/build/release folder.

Unit and (limited) integration tests

You can run basic unit test of the public Server Sent Event endpoints with cargo test. You can run integration tests of the authenticated SSE endpoints (which require a Postgres connection) with cargo test -- --ignored.

Manual testing

Once the streaming server is running, you can also test it manually. You can test it using a browser connected to the relevant Mastodon development server. Or you can test the SSE endpoints with curl, PostMan, or any other HTTP client. Similarly, you can test the WebSocket endpoints with websocat or any other WebSocket client.

Memory/CPU usage

Note that memory usage is higher when running the development version of the streaming server (the one generated with cargo run or cargo build). If you are interested in measuring RAM or CPU usage, you should likely run cargo build --release and test the release version of the executable.

Load testing

I have not yet found a good way to test the streaming server under load. I have experimented with using artillery or other load-testing utilities. However, every utility I am familiar with or have found is built around either HTTP requests or WebSocket connections in which the client sends messages. I have not found a good solution to test receiving SSEs or WebSocket connections where the client does not transmit data after establishing the connection. If you are aware of a good way to do load testing, please let me know.