Warning

The Gossamer Polkadot Host is pre-production software [2022-12-01]

Gossamer is a Golang implementation of the Polkadot Host: an execution environment for the Polkadot runtime, which is materialized as a Web Assembly (Wasm) blob. In addition to running an embedded Wasm executor, a Polkadot Host must orchestrate a number of interrelated services, such as networking, block production, block finalization, a JSON-RPC server, and more.

To get started with Gossamer, follow the steps below to build the source code and start a development network.

Git is required to acquire the Gossamer source code, and Make is used to build it. Building Gossamer requires version 1.20 or higher of Golang.

Clone the Gossamer repository and checkout the development branch:

git clone [email protected]:ChainSafe/gossamer
cd gossamer
git checkout development

Build Gossamer:

make gossamer

Or build Gossamer and move the resulting executable to $GOPATH/bin:

make install

To install Gossamer

A comprehensive guide to Gossamer's end-user capabilities is located in the cmd/gossamer directory. What follows is a guide to Gossamer's capabilities as a Polkadot Host.

A chain specification is a JSON document that defines the genesis block of a blockchain network, as well as network parameters and metadata (e.g. network name, bootnodes, telemetry endpoints, etc). It is necessary to provide Gossamer with a chain specification in order to use it as a Polkadot Host. The Gossamer repository includes a number of chain specifications, some of which will be used in this guide.

Gossamer exposes a number of configuration parameters, such as the location of a chain specification file. Although it's possible to use command-line parameters, this guide will focus on the usage of Gossamer TOML configuration files, which define a set of configuration values in a declarative, portable, reusable format. The chain specifications that are used in this guide are each accompanied by one or more configuration files.

The name of the Polkadot test network is "Westend", and the Gossamer repository includes a chain specification and configuration file for a single-node, local Westend test network.

First, initialize the directory that will be used by the Gossamer node to manage its state:

./bin/gossamer init --force --chain westend-dev

Now, start Gossamer as a host for the local Westend development chain:

./bin/gossamer --chain westend-dev

The multi-node development network includes three participants: the Alice, Bob, and Charlie test accounts. In three separate terminals, initialize the data directories for the three Gossamer instances:

./bin/gossamer init --force --chain westend-local --alice

./bin/gossamer init --force --chain westend-local --bob

./bin/gossamer init --force --config westend-local --charlie

Then start the three hosts:

./bin/gossamer --chain westend-local --alice

./bin/gossamer --chain westend-local --bob

./bin/gossamer --chain westend-local --charlie

In addition to the core functionality provided by Gossamer, we have developed some standalone packages that can be used independently. These packages are located in the pkg directory and serve various utility purposes. Here’s an overview of some of these packages:

To support parity's scale type encoding in golang.
More details here

The trie package includes multiple implementations of polkadot merkle tries. These implementations are useful for various applications requiring efficient data structures. Here are the key implementations:

This implementation supports polkadot merkle tries that are stored entirely in memory. It includes features for backing up the trie using a database to ensure persistence.

An evolution of the in-memory trie, TrieDB introduces lazy loading capabilities from the underlying database. This approach optimizes performance and resource usage by loading data only as needed.

For more details on how to use TrieDB, refer to the specific README

• Check out the Contributing Guidelines and our style guide.
• Have questions or just want to say hi? Join us on Discord!

Our work on Gossamer is funded by the community. If you'd like to support us with a donation:

• DOT: 14gaKBxYkbBh2SKGtRDdhuhtyGAs5XLh55bE5x4cDi5CmL75
• KSM: FAjhFSFoM6X8CxeSp6JE2fPECauCA5NxyB1rAGNSkrVaMtf
• ETH/DAI: 0x764001D60E69f0C3D0b41B0588866cFaE796972c

We take all security issues seriously, if you believe you have found a security issue within a ChainSafe project please notify us immediately. If an issue is confirmed, we will take all necessary precautions to ensure a statement and patch release is made in a timely manner.

Please email us a description of the flaw and any related information (e.g. reproduction steps, version) to security at chainsafe dot io.

GNU Lesser General Public License v3.0