Hyperledger Sawtooth 1.1 (Bumper)

Hyperledger Sawtooth 1.1 (Bumper) is now available. See the documentation to get started.

This page describes the new and changed features in Hyperledger Sawtooth 1.1 (since release 1.0).

Core Sawtooth Components

New Features

  • The consensus API has been completely redesigned. Consensus has been moved to a separate process, called a “consensus engine”. See Hyperledger Sawtooth Consensus for more details.
  • State pruning is now supported at a configurable block horizon. This helps limit the total storage requirements for global state by removing historic state after the configured horizon. Check out the state pruning RFC for more details.
  • Several example transaction processors have been rewritten in Rust, including IntegerKey (intkey), XO, and Smallbank.
  • A new /status endpoint and sawtooth status show command are available to query status information for an active validator.
  • New metrics have been added for submitted batches and transactions, thread pools, transaction processing, and dispatcher queue sizes.
  • The internal metrics library has been refactored to be more modular and similar to the logging API.
  • The gossip protocol used by Sawtooth is now versioned to support backwards-compatible upgrades in the future.

Major Improvements

  • The Rust SDK has matured. It now includes libraries for signing, writing transaction processors, and writing consensus engines, along with supporting information for the auto-generated SDK documentation.
  • Several key items have been rewritten in Rust: Validator CLI argument parsing, global state database (and supporting views), ChainController, and BlockPublisher. This change allows some code to be executed outside of the Python global interpreter lock (GIL).
  • The ChainController and BlockPublisher have been substantially refactored to be more modular and support validating blocks in parallel.

Minor Improvements

  • Transaction processors can now report the maximum number of transactions that they can handle at a time. The validator will only request that many transactions at a time for processing.
  • Logging has been improved to reduce the volume and improve the quality of generated log messages.
  • Discarded blocks are now explicitly canceled to avoid wasting effort on blocks that will never be chosen.
  • Deserialization is now cached for messages that have multiple handlers to avoid redundant work.
  • Peers are requested only from connections that have passed authorization.
  • Client message handling has been moved to a separate thread pool to avoid interfering with transaction processing.
  • The parallel scheduler has been refactored to use a generic PredecessorTree data structure.

Bug Fixes

  • Fixed a bad internal configuration that allowed the Completer and ChainController to get out of sync about which blocks were in the system
  • Add missing handlers for client messages
  • Correctly decrement “time to live” on gossip messages
  • Handled an edge case where a new node will not get the chain until a new block is published
  • Stopped trying to unschedule transactions that haven’t been scheduled yet
  • Fixed a number of concurrency issues where data structure were being accessed concurrently without protection or with incorrect usage of synchronization primitives
  • Fixed a bug where a future could be executed in the event loop instead of in a thread pool
  • Only broadcast to peers that have completed authorization
  • Ensured that candidate blocks are only built in the BlockPublisher thread

Upgrade Considerations

  • The consensus setting sawtooth.consensus.algorithm setting has been deprecated and no longer has an effect. Instead, use the settings sawtooth.consensus.algorithm.name and sawtooth.consensus.algorithm.version to set the name and version of the consensus engine.
  • All SDKs except Rust and Python have been moved from sawtooth-core to separate repositories.
  • PoET has been moved to a new repository.


Hyperledger Sawtooth 1.1 includes a new consensus interface that enables features like language independence for consensus algorithms. Consensus protocols are now implemented as separate processes called “consensus engines”, which enables more consensus options for Sawtooth. Check out the consensus API RFC for more details.

  • The network deployment tools have been updated to launch the consensus processes. If you have made your own custom launch scripts, note that the consensus engine now runs as its own process, like other services such as the REST API and transaction processors. Please see the example Sawtooth docker-compose files for reference.
  • This release includes the following consensus engines based on the new consensus API:
    • PoET consensus engine, a refactored version of the previous PoET consensus module.
    • Dev mode consensus engine, based on the previous dev mode consensus module.
    • New PBFT consensus engine, based on the Practical Byzantine Fault Tolerance (PBFT) consensus algorithm.
    • New Raft consensus engine, based on the Raft consensus algorithm.

Sawtooth PoET

The Sawtooth Proof of Elapsed Time (PoET) consensus can be deployed as a pure Python application using a simulated enclave, called PoET simulator, or with a C++ module implementing an Intel® Software Guard Extensions (Intel® SGX) enclave, called PoET-SGX.

  • PoET simulator is available in the 1.1 release as a consensus engine. If you are using PoET simulator consensus, we recommend upgrading to Sawtooth 1.1.
  • PoET-SGX has not been validated on Sawtooth 1.1. Users relying on PoET-SGX are recommended to remain on Sawtooth 1.0. We are working on a new implementation of poet and its TEE enclave, which is anticipated for a point release in the near future.

Sawtooth Raft

Hyperledger Sawtooth 1.1 supports a developer preview of Sawtooth Raft, a Rust implementation of Raft based on the raft-rs library used by TiKV. The Sawtooth Raft consensus engine uses the new consensus API.

Sawtooth Raft is still in the prototype phase and is under active development.

Sawtooth PBFT

The Hyperledger Sawtooth 1.1 release includes the Sawtooth PBFT consensus engine. Sawtooth PBFT is based on the original PBFT paper with several extensions to make it compatible with Sawtooth and to resolve known issues with the original protocol. See the RFCs for more details:

Sawtooth PBFT is still in the prototype phase and is under active development.


In addition to updates for Hyperledger Sawtooth 1.1 features, technical corrections, and bug fixes throughout, the Sawtooth documentation has the following changes and improvements.

Application Developer’s Guide

API References

System Administrator’s Guide

Architecture Guide

  • General improvements and a new architecture overview.


  • New glossary of Sawtooth terminology.

Smart Contract Engines

Sawtooth Seth

Hyperledger Sawtooth 1.1 continues to support Sawtooth Seth, an Ethereum-compatible transaction family for the Hyperledger Sawtooth platform. Significant changes in this release:

  • A new seth CLI that is capable of communicating with the existing JSON-RPC API. This CLI will let us test the JSON-RPC API, and will eventually allow us to deprecate the existing REST-API-based CLI, which is now available in the seth-cli-go container.
  • The existing JSON-RPC API has been updated to align more closely with existing Ethereum JSON-RPC implementations, particularly in how it handles account management. This change provides better inter-compatibility with off-the-shelf Ethereum tooling.
  • The Burrow version was updated from 0.17 to 0.21 and vendor dependencies were removed.
  • The build process and dependencies have been updated and aligned with current best practices, such as formatting the Rust code and linting it with Clippy.
  • The documentation has been updated with minor corrections.
  • Several minor bugs have been fixed, such as a segfault occurring when creating an account with a nonce, and invalid addresses being displayed in contract listing.
  • This release includes Dockerfiles suitable for publishing to Docker Hub.

Sawtooth Sabre

Hyperledger Sawtooth 1.1 supports Sawtooth Sabre, a transaction family that implements on-chain smart contracts executed in a WebAssembly virtual machine. Sabre smart contracts are stored on chain and executed using the Sabre transaction processor.

Sawtooth Sabre includes an SDK for writing Sabre smart contracts in Rust. The smart contracts can be written in such a way that they can be compiled into transaction processor and run without Sabre. This also makes it easy to convert already-written Rust transaction processors to a Sabre smart contract.

Note: Sabre is currently at version 0.1 and is under active development.

DevOps and CI

Build System Improvements

  • The bin/build_all script and related build scripts have been replaced with docker-compose.
  • The Docker Compose files now have ‘build’ sections, so that pre-building steps aren’t necessary and all required images can be built with a single docker-compose up command.
  • The sawtooth-dev-{lang} Dockerfiles are deprecated. Each component now has its own Dockerfile for development.

Check out the build system RFC for more details.

Note: Requires Docker Engine 18.02.0 or later.


  • Each component now has “installed” Dockerfiles that utilize multi-stage builds. These Dockerfiles are suitable for publishing to a docker registry.

Note: Requires Docker Engine 18.02.0 or later.


  • This release includes example files for two Kubernetes deployments: A five-node network using PoET simulator and a single-node environment using dev mode consensus. The Application Developer’s Guide describes how to use these example files; see the Hyperledger Sawtooth documentation.


The Sawtooth website, sawtooth.hyperledger.org, has been updated with this release. This update includes:

  • A new home page for Hyperledger Sawtooth that provides links to examples, documentation, and timely blog posts.
  • The structure to easily update static content and blog posts.
  • The ability to conduct agile changes, reviews, and approvals through Github.

Expect changes to the Sawtooth website on a regular basis. In the short term, we plan to:

  • Improve website navigation
  • Automate the website build and deployment, based on the model for Sawtooth
  • Apply consistent formatting throughout the site PRs

The Hyperledger Sawtooth Team