Icon LinkDeploying a dApp to Testnet

In this guide, we will deploy a full-stack dApp bootstrapped with npm create fuels to the Fuel testnet.

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Make sure you have already bootstrapped a dApp using npm create fuels. If you haven't, please follow this guide .

There are mainly two steps to get our dApp live on the testnet:

1. Deploying the Contract to the Testnet
2. Deploying the Frontend to the Cloud

Icon LinkDeploying the Contract

We will be using forc Icon Link to deploy our contracts to the testnet. forc is a part of the Fuel Toolchain.

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If you don't have the Fuel Toolchain installed, follow this guide Icon Link to install it.

The first step is to cd into the directory containing your contract:

cd sway-programs/contract

And then, run the following command and follow the instructions to deploy the contract to the testnet:

forc deploy --testnet

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You can check out this guide Icon Link for more information on deploying a contract to the testnet.

You should see a message similar to this:

Contract deploy-to-testnet Deployed!

Network: https://devnet.fuel.network
Contract ID: 0x8342d413de2a678245d9ee39f020795800c7e6a4ac5ff7daae275f533dc05e08
Deployed in block 0x4ea52b6652836c499e44b7e42f7c22d1ed1f03cf90a1d94cd0113b9023dfa636

Copy the contract ID and save it for later use.

Icon LinkDeploying the Frontend

Let's now prepare our frontend so that we can deploy it to the cloud.

Go to your .env.local file and add a new variable named NEXT_PUBLIC_TESTNET_CONTRACT_ID. Set its value to the contract ID you had copied earlier after deploying your contract.

NEXT_PUBLIC_TESTNET_CONTRACT_ID=0x8342d413de2a678245d9ee39f020795800c7e6a4ac5ff7daae275f533dc05e08

If you are curious, this environment variable is used here in the src/pages/index.tsx file to set the contract ID:

const contractId =
  CURRENT_ENVIRONMENT === "local"
    ? contractIds.testContract
    : (process.env.NEXT_PUBLIC_TESTNET_CONTRACT_ID as string); // Testnet Contract ID

You will notice that this piece of code is getting the contract ID depending on the current environment. If the environment is local, it will use the contract ID from the auto-generated contract-ids.json file. Otherwise, for a testnet deployment, it will use the contract ID provided by you.

The CURRENT_ENVIRONMENT variable is defined in the lib.ts file:

type DappEnvironment = 'local' | 'testnet';
 
export const CURRENT_ENVIRONMENT: DappEnvironment =
  (process.env.NEXT_PUBLIC_DAPP_ENVIRONMENT as DappEnvironment) || 'local';

As you can see, it depends on the NEXT_PUBLIC_DAPP_ENVIRONMENT environment variable. If you go to your .env.local file, you will see that it is set to local by default. If you change this value to testnet, the frontend will now be connected to the testnet instead of your local node.

Go ahead and change the NEXT_PUBLIC_DAPP_ENVIRONMENT value to testnet in your .env.local file. If you run your frontend now, you should be able to interact with your contract on the testnet.

To deploy your frontend to the cloud, you can use any service like Vercel Icon Link. Make sure that you setup your environment variables correctly and that your contract ID is correct. Your environment variables should look something like this:

NEXT_PUBLIC_HAS_CONTRACT=true
NEXT_PUBLIC_DAPP_ENVIRONMENT=testnet
NEXT_PUBLIC_TESTNET_CONTRACT_ID=0x8342d413de2a678245d9ee39f020795800c7e6a4ac5ff7daae275f533dc05e08

(the rest of the environment variables are optional)

Icon LinkConclusion

Congratulations! You have successfully deployed your Fuel dApp to the testnet.

To recap, to deploy your dApp to the testnet, you need to:

1. Deploy your contract to the testnet using forc deploy --testnet.
2. Specify this contract ID in your frontend code in src/pages/index.tsx.
3. Set the NEXT_PUBLIC_DAPP_ENVIRONMENT environment variable to testnet.