Contract Deployment Example

Contract deployment examples

Please refer to the Contract example repository.

We'll work through that one in this quick tutorial. The example linked above is a simple smart contract that allows you to store a single value and retrieve it.

It's a great starting point for learning how to deploy a contract to Boba. Let's begin.

Compiling a contract for Boba is identical to compiling a contract for Ethereum mainchain. Notably, all standard solidity compiler versions can be used. For this contract, we will use 0.8.9.

If you check the hardhat.config.ts file, you'll see the following configuration in essence:

networks: {
  boba_sepolia: {
    url: '',
      accounts: [process.env.DEPLOYER_PK],
solidity: {
  version: '0.8.9',
    settings: {
    optimizer: {enabled: true, runs: 200},
etherscan: {
  apiKey: {
      boba_sepolia: "boba", // not required, set placeholder
  customChains: [
      network: "boba_sepolia",
      chainId: 28882,
      urls: {
        apiURL: "",
        browserURL: ""

Now add a .env file that follows the format of env.example with your private key. NOTE: this account must be funded, i.e. contain enough Sepolia ETH to cover the cost of the deployment. Then,

hardhat compile

Yep, it's that easy. You can verify that everything went well by looking for the build directory that contains your new JSON files. Now let's move on to testing!

Woot! It's time to test our contract. Since the JSON RPC provider URL (for Boba Sepolia) has already been specified in your Hardhat config file, all we need to do next is run the test command. Run:

yarn test:integration

You should see a set of passing tests for your contract. You can check a production-grade project here: LightBridge.

$ hardhat test test/contract.spec.ts --show-stack-traces
Using network 'boba_sepolia'.

Compiling your contracts...
> Everything is up to date, there is nothing to compile.

   your tests
Contract deployed at:  0x5FbDB2315678afecb367f032d93F642f64180aa3
     always succeeds
Contract deployed at:  0xe7f1725E7734CE288F8367e1Bb143E90bb3F0512
     contract deployed

  2 passing (3s)

  Done in 3s.

If so, congrats! You're ready to deploy an application to Boba. It really is that easy.

Now we're going to deploy a contract using hardhat.

First, let's create that deployment file. Create a new directory called deploy in the topmost path of your project and create a file within it called contract.deploy.ts.

Next, within contract.deploy.ts, we're going to add the following logic:

console.log(`'Deploying contract...`)

const provider = hre.ethers.provider
const network =

console.log(`Network name=${network?.name}`)

const deployer = new Wallet(network.config.accounts[0], provider)

const Factory__YourContract = new ethers.ContractFactory(

let gasLimit = prompt("Custom gas limit? [number/N]")
if (isNaN(gasLimit?.toLowerCase())) {
  gasLimit = null;
} else {
  gasLimit = parseInt(gasLimit)

YourContract = await Factory__YourContract.deploy({gasLimit})
let res = await YourContract.deployTransaction.wait()
console.log(`Deployed contract: `, res)

console.log(`Contract deployed to: ${YourContract.address}`)

Now we're ready to run our deployment file! Let's go ahead and deploy this contract:

hardhat deploy ./contracts/YourContract.sol --network boba_sepolia

After a few seconds your contract should be deployed. Now you'll see this in your terminal:

$ yarn deploy
yarn run v1.22.15
$ hardhat deploy --network boba_sepolia

Compiling your contracts...
> Everything is up to date, there is nothing to compile.

Starting deployment scripts...
> Network name:    'boba_sepolia'


   Deploying 'YourContract'
   > transaction hash:    0xe7cc5d048ffd426587b7d9c89aed4b0d7b2bd29c5532300bce8a9a57a4c4d689
   > Blocks: 0            Seconds: 0
   > contract address:    0xE769105D8bDC4Fb070dD3057c7e48BB98771dE15
   > block number:        6270
   > block timestamp:     1635787822
   > account:             0x21724227d169eAcBf216dE61EE7dc28F80CF8A92
   > balance:             0.901997296123301024
   > gas used:            855211 (0xd0cab)
   > gas price:           0.02 gwei
   > value sent:          0 ETH
   > total cost:          0.00001710422 ETH

   > Saving artifacts
   > Total cost:       0.00001710422 ETH

> Total deployments:   1
> Final cost:          0.00001710422 ETH

  Done in 10.11s.

That's pretty much it. Contracts deployed! Tutorial complete. Hopefully now you know the basics of working with Boba!

Example project not working? Create a Github Issue.

Last updated