WARaft

WARaft is an Erlang implementation of the Raft consensus protocol.

This repository is a FerricStore-maintained distribution of Meta Platforms' Apache-2.0 licensed WARaft code. It preserves the original copyright notices, license, OTP application name, module names, and public API surface.

FerricStore uses WARaft as its durable consensus engine dependency.

Status

• Package name: ferricstore_waraft
• OTP application: wa_raft
• Current release: v0.1.0
• License: Apache-2.0
• Runtime dependencies: none beyond Erlang/OTP kernel and stdlib

This repository is intended to be a stable, packageable WARaft dependency for FerricStore and other Erlang/Elixir systems that need a pluggable Raft engine.

Features

• Raft consensus implementation for replicated state machines.
• Pluggable storage, log, state machine, and transport behavior interfaces.
• Single-node bootstrap and multi-node membership support.
• Erlang/OTP supervision integration.
• No NIFs and no Rust code in this repository.

FerricStore's high-performance log/storage adapters live in the FerricStore repository, not in this wa_raft package.

Installation

Git dependency

Until the Hex package is published, use the Git tag:

{deps, [
    {wa_raft, {git, "https://github.com/ferricstore/waraft.git", {tag, "v0.1.0"}}}
]}.

For Elixir/Mix projects:

{:wa_raft, github: "ferricstore/waraft", tag: "v0.1.0", manager: :rebar3}

Hex dependency

After the Hex package is published:

{deps, [
    {wa_raft, "0.1.0", {pkg, ferricstore_waraft}}
]}.

For Elixir/Mix projects:

{:wa_raft, "~> 0.1", hex: :ferricstore_waraft, manager: :rebar3}

Quick start

The following example starts a single-node Raft partition and performs one write and one read. It uses the built-in ETS log/storage path for demonstration. Production systems should provide storage and log modules appropriate for their durability and recovery requirements.

rr(wa_raft_server).
application:ensure_all_started(wa_raft).
application:set_env(test_app, raft_database, ".").

Spec = wa_raft_sup:child_spec(test_app, [#{table => test, partition => 1}]).
supervisor:start_child(kernel_sup, Spec).

Config = wa_raft_server:make_config([
    #raft_identity{name = raft_server_test_1, node = node()}
]).

wa_raft_server:bootstrap(
    raft_server_test_1,
    #raft_log_pos{index = 1, term = 1},
    Config,
    #{}
).

wa_raft_server:status(raft_server_test_1).
wa_raft_acceptor:commit(raft_acceptor_test_1, {make_ref(), {write, test, key, 1000}}).
wa_raft_acceptor:read(raft_acceptor_test_1, {read, test, key}).

Expected read result:

{ok, 1000}

Public API orientation

The main modules are:

• wa_raft_sup: builds supervisor child specs for Raft tables/partitions.
• wa_raft_server: bootstrap, membership, status, promotion, and Raft server operations.
• wa_raft_acceptor: commit/read entry point used by clients.
• wa_raft_storage: behavior/API for state machine storage.
• wa_raft_log: behavior/API for Raft log implementations.
• wa_raft_transport: behavior/API for network transport.

Headers are included with:

-include_lib("wa_raft/include/wa_raft.hrl").

That include path works for both Git and Hex dependencies because the OTP app is named wa_raft.

Development

rebar3 compile
rebar3 xref
rebar3 dialyzer
rebar3 edoc

Common local check:

rebar3 do compile,xref

Versioning

This repository starts at 0.1.0 because it is a maintained distribution used by FerricStore. The original upstream app version was not used as the package release version here.

License and attribution

WARaft is licensed under Apache-2.0. See LICENSE and NOTICE.

This repository preserves Meta Platforms' original copyright notices. FerricStore maintains this distribution but does not claim Meta endorsement.