How to Deploy a Harmony Devnet for Testing and Development

Harmony is a fast and scalable blockchain that is designed to support decentralized applications (dApps). One of the key features of Harmony is its ability to create and deploy private blockchains, called Devnets. Devnets are a great way for developers to test their dApps in a safe and controlled environment.

In this article, we will walk you through the steps on how to deploy a Harmony Devnet. We will use the Harmony CLI to create and configure our Devnet, and we will use the Remix IDE to deploy our smart contract to our Devnet.

Prerequisites

Before you can deploy a Harmony Devnet, you will need the following:

• A Harmony wallet (such as MetaMask)

• Some ONE tokens to pay for gas fees

• The Harmony CLI

• The Remix IDE

Step 1: Create a Devnet

The first step is to create a Devnet. We can do this using the following command:

Code snippet harmony create-devnet Use code with caution.

This will create a new Devnet with the default settings. We can specify the name of our Devnet and the number of validators using the following options:

Code snippet --name <name> --validators <number> Use code with caution.

For example, to create a Devnet named "my-devnet" with 3 validators, we would use the following command:

Code snippet harmony create-devnet --name my-devnet --validators 3 Use code with caution.

Step 2: Configure the Devnet

Once we have created our Devnet, we need to configure it. We can do this using the following command:

Code snippet harmony config-devnet Use code with caution.

This will open a configuration file in our default text editor. We can specify the following settings in the configuration file:

• The RPC endpoint

• The block gas limit

• The block time

• The genesis file

For example, to set the RPC endpoint to "localhost:8545", the block gas limit to 10000000, the block time to 10 seconds, and the genesis file to "genesis.json", we would add the following lines to the configuration file:

Code snippet rpcEndpoint = "localhost:8545" blockGasLimit = 10000000 blockTime = 10 genesisFile = "genesis.json" Use code with caution.

Step 3: Deploy a Smart Contract to the Devnet

Now that our Devnet is configured, we can deploy a smart contract to it. We can do this using the Remix IDE.

In Remix, create a new file and paste the following code:

Code snippet pragma solidity ^0.8.0; contract Counter { uint256 public counter; function increment() public { counter++; } function getCounter() public view returns (uint256) { return counter; } } Use code with caution.

Save the file as "counter.sol".

In Remix, click on the "Deploy" button next to the "counter.sol" file. You will be prompted to enter a name for your contract and to specify the amount of ONE tokens you want to pay for gas fees.

Once you have entered the required information, click on the "Deploy" button. Once the deployment is complete, you will see a message that says "Contract Deployed Successfully".

Step 4: Interacting with the Smart Contract

Now that our smart contract has been deployed, we can interact with it using MetaMask.

In MetaMask, connect to the Harmony Devnet. Then, enter the address of your deployed smart contract and click on the "Connect" button.

Once your smart contract is connected, you can interact with it using the functions that you defined in your smart contract. For example, you can increment the counter by clicking on the "Increment" button.

You can also get the current value of the counter by clicking on the "Get Counter" button.

Conclusion

In this article, we have walked you through the steps on how to deploy a Harmony Devnet. We have used the Harmony CLI to create and configure our Devnet, and we have used the Remix IDE to deploy our smart contract to our Devnet.

We hope this article has been helpful. If you have any questions, please feel free to leave a comment below.