The Raft Consensus Algorithm

Raft Visualization

Here’s a Raft cluster running in your browser. You can interact with it to see
Raft in action. Five servers are shown on the left, and their logs are shown on
the right. We hope to create a screencast soon to explain what’s going on. This
visualization (RaftScope)
is still pretty rough around the edges; pull requests would be very welcome.

The Secret Lives of Data
is a different visualization of Raft. It’s more guided and less interactive, so
it may be a gentler starting point.

Publications

This is “the Raft paper”, which describes Raft in detail:
In Search of an Understandable Consensus Algorithm (Extended Version)
by Diego Ongaro and
John Ousterhout.
A slightly shorter version of this paper received a Best Paper Award at the
2014 USENIX Annual Technical Conference.

Diego Ongaro’s
Ph.D. dissertation
expands on the content of the paper in much more detail, and
it includes a simpler cluster membership change algorithm.

More Raft-related papers:

• Doug Woos,
  James R. Wilcox,
  Steve Anton,
  Zachary Tatlock,
  Michael D. Ernst, and
  Thomas Anderson.
  
  
  
  Planning for Change in a Formal Verification of the Raft Consensus Protocol.
  
  
  
  Certified Programs and Proofs (CPP), January 2016.

• James R. Wilcox,
  Doug Woos,
  Pavel Panchekha,
  Zachary Tatlock,
  Xi Wang,
  Michael D. Ernst, and
  Thomas Anderson.
  
  
  
  Verdi: A Framework for Implementing and Verifying Distributed Systems.
  
  
  
  Programming Language Design and Implementation (PLDI), June 2015.

• Hugues Evrard and
  Frédéric Lang.
  
  
  
  Automatic Distributed Code Generation from Formal Models of Asynchronous Concurrent Processes.
  
  
  
  Parallel, Distributed, and Network-Based Processing (PDP), March 2015.

• Heidi Howard,
  Malte Schwarzkopf,
  Anil Madhavapeddy, and
  Jon Crowcroft.
  
  
  
  Raft Refloated: Do We Have Consensus?.
  
  
  
  SIGOPS Operating Systems Review, January 2015.

• Heidi Howard.
  
  
  
  ARC: Analysis of Raft Consensus.
  
  
  
  University of Cambridge, Computer Laboratory, UCAM-CL-TR-857, July 2014.

Talks

These talks serve as good introductions to Raft:

• Talk on Raft at
  CS@Illinois Distinguished Lecture Series
  by John Ousterhout, August 2016:
  

• Talk on Raft and its TLA+ spec as part of
  Dr. TLA+ Series
  by Jin Li, July 2016:
  

• Talk on Raft at
  Build Stuff 2015
  by Diego Ongaro, November 2015:
  

• Talks on Rust, Raft, and distributed systems at
  Rust Bay Area Meetup
  by
  Yvonne Coady,
  Diego Ongaro,
  Andrew Hobden,
  Dan Burkert, and
  Alex Newman,
  August 2015:
  

• Talk on Raft at
  CoreOS Fest 2015
  by Diego Ongaro, May 2015:
  

• Talk on Raft at
  Sourcegraph meetup
  by Diego Ongaro, April 2015:
  

• Talk on Raft at LinkedIn
  by Diego Ongaro, September 2014:
  

• Talk on Raft at
  USI 2014
  and
  /dev/summer 2014
  by Arnaud Bailly, July 2014:
  

• Talk on Raft at 2014 USENIX Annual Technical Conference
  by Diego Ongaro, June 2014:
  

• Talk on Raft at CraftConf 2014
  by Diego Ongaro, April 2014:
  

• Talk on Raft at Rubyconf 2013
  by Patrick Van Stee, November 2013:
  

• Talk on Raft at RICON West 2013
  by Diego Ongaro, October 2013:
  

• Talk on Raft at Strange Loop 2013
  by Ben Johnson, September 2013:
  

• Talk on Raft and Rafter
  at the Erlang NYC Meetup
  by Tom Santero and
  Andrew Stone, August 2013:
  

• Talk on Raft (venue unknown)
  by Patrick Van Stee, July 2013:
  

• Lecture for the Raft User Study
  by John Ousterhout, March 2013:
  

Courses teaching Raft

This is a list of courses that include lectures or programming assignments on Raft.
This might be useful for other instructors and for online learners looking for materials.
If you know of additional courses, please submit a
pull request
or an issue to update it.

• University of California, San Deigo,
  CSE224: Graduate Networked Systems,
  George Porter.
  Includes lecture on Raft and programming assignment (Go) to develop a fault-tolerant Dropbox clone. (Winter 2023/2022, Fall 2020/2019/2018 …)
• Technical University of Munich,
  IN2259: Distributed Systems,
  Pramod Bhatotia and
  Martin Kleppmann.
  Includes lecture on Raft. (Winter 2022/2023, …)
• University of Illinois Urbana-Champaign,
  CS425: Distributed Systems,
  Indranil Gupta,
  Nikita Borisov, and
  Radhika Mittal.
  Includes Raft programming assignment in Go. (Spring 2021, …)
• The Chinese University of Hong Kong,
  CSCI4160: Distributed and Parallel Computing (Private),
  Eric Lo.
  Includes lecture on Paxos and Raft as well as Raft programming assignment in Java/Go
  (Fall 2019, Spring 2021, …)
• Indian Institute of Technology Delhi,
  COL 819: Distributed Systems,
  Smruti R. Sarangi.
  Includes lecture on Raft (video)
  (PPTX)
  (Winter 2020, …)
• Carnegie Mellon University,
  CS 440: Distributed Systems,
  Yuvraj Agarwal,
  Dave Andersen.
  Includes Raft programming assignment in Go. (Fall 2019, …)
• Northeastern University,
  CS 3700: Networks and Distributed Systems,
  Christo Wilson,
  Long Lu.
  Includes an assignment to build a replicated key-value store based on the Raft protocol. (Fall 2018, …)
• Institute Technology Bandung,
  IF3230.
  Raft assignments with testcases for showcasing edge cases and scoring
  (2018)
• Rose-Hulman Institute of Technology,
  CS 403: Programming Language Paradigms,
  Buffalo Hewner.
  Includes Raft programming assignment in Erlang (assignments).
  (Winter 2017, …)
• Princeton University,
  COS-418: Distributed Systems,
  Mike Freedman and
  Kyle Jamieson.
  Includes lecture on Raft
  (PPTX) and
  programming assignments
  to build a Raft-based key-value store.
  (Fall 2016, …)
• University of Washington,
  CSE 452: Distributed Systems,
  Tom Anderson.
  Includes lecture on Raft,
  though they call it Paxos.
  (Winter 2016, …)
• University of Colorado, Boulder,
  CSCI 5673: Distributed Systems,
  Shivakant Mishra.
  Includes assignment to download a Raft implementation and build a fault-tolerant data structure with it.
  (Fall 2015, …)
• University of Utah,
  CS 6963: Distributed Systems,
  Ryan Stutsman
  (@rstutsman).
  Will include something about Raft (TBD).
  (Fall 2015, …)
• San Jose State University,
  CMPE 275 Enterprise Application Development,
  John Gash.
  Includes project to make a distributed filesystem using Raft.
  (Spring 2015, …)
• Brown,
  CS 138: Distributed Computer Systems,
  Tom Doeppner,
  Rodrigo Fonseca
  (@rodrigo_fonseca).
  Includes Raft programming assignment in Go.
  (Spring 2015, …)
• MIT,
  6.824: Distributed Systems,
  Robert Morris.
  Includes lecture on Raft
  (lecture notes).
  See Jon Gjengset‘s posts for
  instructors and
  students.
  (Spring 2015, …)
• University of San Francisco,
  CS 636: Graduate Operating Systems,
  Greg Benson
  (@gregorydbenson).
  Includes lecture on Raft.
  (Spring 2015, …)
• Harvard,
  CS 261: Research Topics in Operating Systems,
  Margo Seltzer.
  Includes lecture on Raft
  (lecture notes).
  (Fall 2014, …)
• University of Houston,
  COSC 6360: Operating Systems,
  Jehan-François Pâris
  (@jehanfrancois).
  Includes lecture on Raft (PPT).
  (Fall 2014, …)
• Stanford,
  CS 244b: Distributed Systems,
  Dawson Engler,
  David Mazières
  (@dmazieres).
  Included guest lecture on Raft by Diego Ongaro.
  Several students chose to work on Raft-based
  final projects.
  (Fall 2014)
• NUST-SEECS,
  CS 332: Distributed Computing,
  Tahir Azim
  (@TahirAzim).
  Includes lecture on Raft based on user study materials
  (tweet).
  (Fall 2014, …)
• Duke,
  CPS 512: Distributed Systems,
  Bruce Maggs.
  Includes guest lecture on Raft
  (PPTX)
  by Landon Cox
  (@lpcox).
  (Spring 2014, Spring 2015, …)
• IIT Bombay,
  CS 733: Cloud Computing,
  Sriram Srinivasan.
  Includes Raft programming assignment in Go (assignments).
  (Spring 2014, Spring 2015, …)

Where can I ask questions?

The best place to ask questions about Raft and its implementations is the
raft-dev Google group.
Some of the implementations also have their own mailing lists; check their READMEs.

Where can I get Raft?

There are many implementations of Raft available in various stages of
development. This table lists the implementations we know about with source
code available. The most popular and/or recently updated implementations are
towards the top. This information will inevitably get out of date; please submit a
pull request
or an issue to update it.