Deploying a Contract

To deploy the HelloWorld.sol contract, do the following:

Install the dotenv package in your project directory.
```
npm install dotenv --save
```
Create a file called .env in the project directory with the following contents.
```
API_URL = "https://eth-goerli.g.alchemy.com/v2/your-api-key"
PRIVATE_KEY = "your-metamask-private-key"
```
Follow these instructions to export your private key from Metamask. The API_URL needs to be copied from your Alchemy account.

NOTE: If you are going to push the project code to a public Github/Gitlab repository, remember to add the .env file to your .gitignore.

Install Ethers.js by running the following command

npm install --save-dev @nomiclabs/hardhat-ethers "ethers@^5.0.0"

Update the hardhat.config.js file to have the following content.

/**
* @type import('hardhat/config').HardhatUserConfig
*/

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

const { API_URL, PRIVATE_KEY } = process.env;

module.exports = {
solidity: "0.8.17",
defaultNetwork: "goerli",
networks: {
    hardhat: {},
    goerli: {
        url: API_URL,
        accounts: [`0x${PRIVATE_KEY}`]
    }
},
}

Create a directory called scripts
```
mkdir scripts
```

Create a file called deploy.js in the scripts directory with the following content.

async function main() {
    const HelloWorld = await ethers.getContractFactory("HelloWorld");

    // Start deployment, returning a promise that resolves to a contract object
    const hello_world = await HelloWorld.deploy("Hello World!");   
    console.log("Contract deployed to address:", hello_world.address);
}

main()
.then(() => process.exit(0))
.catch(error => {
    console.error(error);
    process.exit(1);
});

Deploy the contract by running the following command.
```
npx hardhat run scripts/deploy.js --network goerli
```
You should see a message of the following form. The address will be different in your case.
```
Contract deployed to address: 0xD1aEf927a80301b63dE477afe2410F25bf8Baf6a
```
Save the contract address somewhere. It will be used in the next section.

Ethereum Lab

Deploying a Contract