Gasless-MetaTransactions-with-OpenZeppelin-Defender

Code for the workshop on Meta-Transactions using OpenZeppelin Defender.

This project consists of a sample names registry contract, that accepts registrations for names either directly or via a meta-transaction, along with a client dapp, plus the meta-transaction relayer implementation.

Live demo running at defender-metatx-workshop-demo.openzeppelin.com.

Structure

app: React code for the client dapp, bootstrapped with create-react-app.
autotasks/relay: Javascript code for the meta-transaction relay, to be run as a Defender Autotask, compiled using rollup.
contracts: Solidity code for the Registry contract, compiled with hardhat.
scripts: Custom scripts for common tasks, such as uploading Autotask code, signing sample meta-txs, etc.
src: Shared code for signing meta-txs and interacting with the Forwarder contract.
test: Tests for contracts and autotask.

Scripts

yarn deploy: Compiles and deploys the Registry and Forwarder contracts to xDAI, and writes their addresses in deploy.json.
yarn sign: Signs a meta-tx requesting the registration of NAME, using the private key defined in PRIVATE_KEY, and writes it to tmp/request.json.
yarn events: Lists all the Registered events from the deployed contract on xDAI.
yarn invoke: Invokes the relay Autotask via WEBHOOK_URL with the contents of tmp/request.json generated by yarn sign.
yarn upload: Compiles and uploads the Autotask code to AUTOTASK_ID.
yarn relay: Runs the relay Autotask script locally, using the Defender Relayer for RELAY_API_KEY.
yarn test: Runs tests for contracts and Autotask using hardhat.

Environment

Expected .env file in the project root:

PRIVATE_KEY: Private key used for deploying contracts and signing meta-txs locally.
RELAYER_API_KEY: Defender Relayer API key, used for sending txs with yarn relay.
RELAYER_API_SECRET: Defender Relayer API secret.
AUTOTASK_ID: Defender Autotask ID to update when running yarn upload.
TEAM_API_KEY: Defender Team API key, used for uploading autotask code.
TEAM_API_SECRET: Defender Team API secret.

Expected .env file in /app:

REACT_APP_WEBHOOK_URL: Webhook of the Autotask to invoke for relaying meta-txs.
REACT_APP_QUICKNODE_URL: Optional URL to Quicknode for connecting to the xDAI network from the dapp.

Run the code

To run the workshop code yourself on the xDai network you will need to sign up to Defender and apply for mainnet access, or change the code to use a public testnet.

Fork and clone the repo

First fork the repository and then Git Clone your fork to your computer and install dependencies

$ git clone https://github.com/[GitHub username]/workshops.git
$ cd workshops/01-defender-meta-txs/
$ yarn

Configure the project

Create a .env file in the project root

PRIVATE_KEY="Private key used for deploying contracts and signing meta-txs locally"
RELAYER_API_KEY="Defender Relayer API key, used for sending txs with yarn relay"
RELAYER_API_SECRET="Defender Relayer API secret"
AUTOTASK_ID="Defender Autotask ID to update when running yarn upload"
TEAM_API_KEY="Defender Team API key, used for uploading autotask code"
TEAM_API_SECRET="Defender Team API secret"

Store the value of a new private key in our projects .env file and fund the address with xDai (You can use a faucet).

Deploy contracts

Deploy the MinimalForwarder and Registry contracts to xDai

$ yarn deploy

Create Relayer

Create a relayer using Defender Relay on xDai. Fund your xDai relayer (You can use a faucet). Create an API key for your relayer and store the relayer API key and API secret in our projects .env file.

Sign a request to register a name, this will create a request in tmp/request.json that we can then view

$ NAME=alice yarn sign
$ cat tmp/request.json

We can then use the script to send the request to our relayer, and view the transaction on Blockscout. We can also view the name registrations.

$ yarn relay
$ yarn events

Create Autotask

Create an Autotask in Defender, with a webhook trigger and connected to our xDai relayer. We can leave the code as is as we will update it using a script.

Once the Autotask is created get the Autotask ID from the URL (https://defender.openzeppelin.com/#/autotask/[AUTO_TASK_ID]) and store it in our projects .env file.

To update our Autotask we need a Team API key. From the right hand menu in Defender, select Team API Keys, then Create API Key, with Capabilities to Update Autotasks code and a note such as Update Autotask code. Copy the Team API key and secret and store it in our projects .env file.

We can then update our Autotask code programmatically by uploading our code:

$ yarn upload

We can sign another name for the registry and then send a request to the Autotask webhook to relay and finally view the registry.

$ NAME=alice yarn sign
$ curl -XPOST 'Your Autotask Webhook URI goes here' -H 'Content-type: application/json' -d '@tmp/request.json'
$ yarn events

Run app

Copy the Autotask Webhook URI and store in our apps .env file (in the app directory).

We can then install dependencies using yarn and run the app.

$ yarn
$ yarn start

Open app: http://localhost:3000/
Connect MetaMask to xDai network and change to xDai network
Enter a name to register and sign the metatransaction in MetaMask
Your name will be registered, showing the address that created the metatransaction and the name.

Syedmoizulhassanshah/Gasless-MetaTransactions-with-OpenZeppelin-Defender