Raft

Note: This project is incomplete and the code is of pre-alpha quality. Only some specific, basic functionality is available, and I need your help defining an API!

Blog Updates

Problem and Importance

When building a distributed system one principal goal is often to build in fault-tolerance. That is, if one particular node in a network goes down, or if there is a network partition, the entire cluster does not fall over. The cluster of nodes taking part in a distributed consensus protocol must come to agreement regarding values, and once that decision is reached, that choice is final.

Distributed Consensus Algorithms often take the form of a replicated state machine and log. Each state machine accepts inputs from its log, and represents the value(s) to be replicated, for example, a hash table. They allow a collection of machines to work as a coherent group that can survive the failures of some of its members.

Two well known Distributed Consensus Algorithms are Paxos and Raft. Paxos is used in systems like Chubby by Google, and Raft is used in things like etcd. Raft is generally seen as a more understandable and simpler to implement than Paxos, and was chosen for this project for this reason.

Compiling

For Linux or Mac, with root! Windows users are, unfortunately, on their own.

You will need the Rust compiler:

curl -L https://static.rust-lang.org/rustup.sh | sudo sh

This should install cargo and rustc. Next, you'll need capnp to build the messages.canpnp file . It is suggested to use the git method

git clone https://github.com/sandstorm-io/capnproto.git
cd capnproto/c++
./setup-autotools.sh
autoreconf -i
./configure
make -j6 check
sudo make install

Finally, clone the repository and build it:

git clone git@github.com:Hoverbear/raft.git && \
cd raft && \
cargo build

Note this is a library, so building won't necessarily produce anything useful for you.

Documentation

Testing

You can run raft's full bank of tests with all debug output like so:

RUST_LOG=raft=debug cargo test -- --nocapture

Due to the nature of this library's pre-alpha state, some tests may occasionally fail. I'm working on this.

For something more terse use cargo test.

The tests/lib.rs file currently hosts a working example of using the library. Before you say anything, yes, I know it's not nice. Let's talk about how to make that much nicer!

Project Website

I'll keep track of my progress both on my blog through the Raft tag, and via Github.

s4nch3z / raft