Awesome

Smart Contracts - running in Wasm

Web Assembly (Wasm) is "a new code format for deploying programs that is portable, safe, efficient, and universal.”

This repo provides the PoC for a writing a smart contract runs inside a Wasm engine. This Wasm engine is hosted by a golang chaincode that implements the gRPC to talk back to the peer, and route calls to the guest code in the Wasm engine.

Usage

This is an early prototype for running Wasm chaincode as an external service using the waPC Go Host.

It can be used with the fabric-builders builder project. The instructions below assume that you have a Fabric network configured to use hyperledgendary/fabric-builder-peer images. See the "Chaincode as an external service" documentation for more information.

Note: each organization in a Fabric network will need to follow the instructions below to host their own instance of the Wasm chaincode external service.

Packaging and installing the Wasm chaincode

Create a connection.json file with details of how Fabric will connect to your external service. For example:

{
  "address": "wasmcc.example.com:9999",
  "dial_timeout": "10s",
  "tls_required": false
}

Package the connection.json file using the pkgcc.sh script. For example:

pkgcc.sh -l wasmftw -t external connection.json

This should produce a wasmftw.tgz file which can be installed using the peer lifecycle chaincode install command.

Running the Wasm chaincode external service

To run the service in a container, build a FabCar docker image:

docker build -t hyperledgendary/fabric-chaincode-wasm .

The Wasm chaincode requires three environment variables to run, CHAINCODE_SERVER_ADDRESS, CHAINCODE_ID, and CHAINCODE_WASM_FILE, which are described in the chaincode.env.example file. Copy the example file to chaincode.env and edit it before starting the Wasm chaincode container.

Once you have edited the chaincode.env file, start the container using the docker run command. For example,

docker run -it --rm -v ${PWD}/contracts:/local:ro --name wasmcc.example.com --hostname wasmcc.example.com --env-file chaincode.env --network=small_fabricdev hyperledgendary/fabric-chaincode-wasm

Note: this assumes you are running a Fabric network using docker-compose. The value of --network will depend on your configuration

Using the Wasm chaincode

Once you have installed and started the Wasm chaincode, you'll need to approve and commit it as usual. It should then work in exactly the same was as any other chaincode.