Hardhat – How to Read Config Programmatically at Runtime and Log Attributes

configurationhardhatrpc

I want to add some nice output in my hardhat scripts for showing what my configurations are during a test run. I run the script locally while changing configuration variables and I want the console output to reflect those config changes so that I can more easily track things.

For example, here is my hardhat.config.js:

require("@nomiclabs/hardhat-waffle");
require("dotenv").config();

/**
 * @type import('hardhat/config').HardhatUserConfig
 */
module.exports = {
  solidity: "0.8.4",
  networks: {
    rinkeby: {
      url: process.env.ALCHEMY_URL,
      // url: process.env.INFURA_URL,
      // url: process.env.QUICKNODE_URL,
      // url: process.env.MORALIS_URL,
      accounts: [process.env.PK]
    }  
  }
};

And here is my workflow:

  1. run the script with existing settings
thatguyintech@albert eth-call-analysis % npx hardhat run scripts/sample-script.js
rpc url: localhost
GasLimits contract deployed to: 0x5FbDB2315678afecb367f032d93F642f64180aa3
  1. change the url config and re-run
thatguyintech@albert eth-call-analysis % npx hardhat run scripts/sample-script.js --network rinkeby
rpc url:  https://eth-rinkeby.alchemyapi.io/v2/<my api key>
GasLimits contract deployed to: 0xeb8aeddb118b8141ea4e0e0e0d7e7ee685f214ac

In order to get the above output, my sample-script.js looks like this:

const hre = require("hardhat");

async function main() {
  console.log("rpc url: ", process.env.ALCHEMY_URL) // I have to manually change this on each run.

  // We get the contract to deploy
  const GasLimits = await hre.ethers.getContractFactory("GasLimits");
  const gasLimits = await GasLimits.deploy();

  await gasLimits.deployed();

  console.log("GasLimits contract deployed to:", gasLimits.address);
}

Is there a way to read the hardhat.config.js values at runtime so that I don't have to rely on dotenv and change my script manually on each run?

Specifically, is there a way to rewrite console.log("rpc url: ", process.env.ALCHEMY_URL) into something that can automatically update based on how I've set my hardhat.config.js? Maybe something like this: console.log("rpc url: ", hre.config.networks.url)?

Update: I do see in the hardhat runtime environment docs that there is an hre.config object I can use. However, I don't want to know about the original configuration, I want to know the network that is currently be used at runtime at the time that my script is invoked. Any tips for that?

Best Answer

Great question; try something like this:

Use hre.network.config.url;

Here is an example of how you can get the RPC Provider URL at runtime in your deploy.js script:

const hre = require("hardhat");

console.log("provider url: ", hre.network.config.url);

So then, for example if you run the deploy locally, the provider URL might be undefined:

% npx hardhat run scripts/deploy.js
provider url:  undefined

But if you switch to a network that you have defined, you will then see the api provider URL:

% npx hardhat run scripts/deploy.js --network rinkeby
provider url:  https://eth-rinkeby.alchemyapi.io/v2/<api-key>
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