feat requrest: custom ethereum chain with hardhat-viem plugin

[y0sher]

Describe the feature

Description

My project is using hardhat-viem

When setting up a local Ethereum development network ( not hardhat/foundry, a whole ethereum network ), in hardhat.config.ts, e.g:

  config.networks = {
    devnet: {
      chainId: 3113031,
      url: `localhost:mygeth`,
      accounts: [
        "myaccount"
      ],
      gasPrice: '',
      gas: '',
    }
}

I'm getting this error:

Error in plugin @nomicfoundation/hardhat-viem: No network with chain id 3113031 found. You can override the chain by passing it as a parameter to the client getter:

import { someChain } from "viem/chains";
const client = await hre.viem.getPublicClient({
  chain: someChain,
  ...
});

You can find a list of supported networks here: https://github.com/wevm/viem/blob/main/src/chains/index.ts

For more info run Hardhat with --show-stack-traces

Feature request

I want to be able to direct hardhat-viem to my defined chainId and node url, should probably use defineChain from viem, somewhere around this codepath I guess. I tried to sketch up some code, but it seems not as trivial since EthereumProvider doesn't exposes the json url.

Search terms

No response

[iosh]

Yes, you can use defineChain to define your own chain, as shown in the code below.

import hre from "hardhat";
import { defineChain } from "viem";

async function main() {
  const myChain = defineChain({
    name: "mygeth",
    id: 3113031,
    nativeCurrency: {
      name: "mygeth",
      symbol: "mygeth",
      decimals: 18,
    },
    rpcUrls: {
      default: {
        http: ["http://localhost:mygeth"], 
      },
    },
  });

  const publicClient = await hre.viem.getPublicClient({ chain: myChain });

  const walletClient = await hre.viem.getWalletClient("0x......", {
    chain: myChain,
  });
  console.log(await publicClient.getBlock());

  console.log(await walletClient.getChainId());
}

[ChristopherDedominici]

Closing this issue as the solution proposed by @iosh works as expected.