Developers

How To Use DappTools

February 15, 2022 6 min read
Author: Chainlink

When it comes to writing smart contracts, developers only need to know one language, such as Solidity, Vyper, or Rust. However, choosing a framework and learning all the languages around that framework can be tricky.

Learning a minimalistic command line framework like DappTools removes these issues, and makes life as a Web3 developer much easier. 

In this DappTools tutorial, you’ll learn how to create, test, and deploy your smart contracts through the DappTools framework. 

Check out the video to accompany this tutorial:

 

What Is DappTools? 

DappTools is a framework like Hardhat and Brownie that helps smart contact developers test, deploy, and maintain their code. If you deploy a contract, where do you store the compiled bytecode? How are you keeping track of where it went? How easy is it to redeploy new code? All these are issues solved by using a smart contract development framework. 

DappTools was originally written in Haskell. Recently however, the Paradigm team adopted DappTools and rewrote it in Rust, calling their new creation Foundry. Both work similarly in that they are command line-focused, fast, and often involve writing Solidity tests with a lot of fuzzing. 

DappTools is a popular choice for a number of leading protocols. 

Why Use DappTools? 

If you’re a developer who loves Linux, bash shells, and fast, command line-centric coding, then this is definitely a framework for smart contracts that you should try out. Additionally, if you’re not familiar with JavaScript or Python, this will work great for you too!

What Are We Learning? 

In this tutorial, we are going to learn how to:

  1. Work with DappTools
  2. Deploy Chainlink-powered hybrid smart contracts using the dapptools-starter-kit

Here are a few examples of using Chainlink services with this starter kit:

Installation

Requirements

First, we need to install a few things. 

You probably already have it installed, but if not you’ll need make. Follow these steps to check whether you have it installed.

Getting Started 

Once we have installed these tools, we can clone the starter kit repo and begin working on it.

sh
git clone https://github.com/smartcontractkit/dapptools-starter-kit
cd dapptools-starter-kit
make # This installs the project's dependencies.
make test

Now you have the files, let’s go through what everything does:

  • Makefile: Where you put your scripts. DappTools is command line based, and our makefile helps us run large commands with a few characters.
  • lib: This folder is for external dependencies, like OpenZeppelin or ds-test.
  • out: Where your compiled code goes. Similar to the build folder in Brownie or the artifacts folder in Hardhat.
  • src: This is where your smart contracts are. Similar to the contracts folder in Brownie and Hardhat.

Testing 

Let’s do some testing! To test we can run either make test or dapp test.

All the commands from DappTools work with this repo, including dapp build, ethsign, and dapp test. 

Importing External Dependencies

Let’s say we want to create an NFT using the OpenZeppelin standard. To install external contracts or packages, we can use the dapp install command. We need to name the GitHub repo organization and the repo name to install.

First, we need to commit our changes so far. DappTools brings external packages in as git submodules, so we need to commit first.

Run:

git add .
git commit -m ‘initial commit’

Then, we can install our external packages. For example, for OpenZeppelin, we’d use:

dapp install OpenZeppelin/openzeppelin-contracts

You should now see a new folder in your lib folder labeled openzeppelin-contracts, since it’ll have downloaded from GitHub. This repo already starts with OpenZeppelin contracts, so there’s been some duplication, but we still got to see how it works.

Deploying

To deploy, you first need to setup your ethsign and your .env files. 

Set Up Your Account/ethsign

To get your private keys into DappTools, you can either use a keystore or ethsign. ethsign comes with the install of dapptools. For ethsign, run the following:

bash
ethsign import 

You’ll now be prompted for your private key and a password. You can get a private key from a wallet like MetaMask. Once successful, add the address of the private key to your .env file under an ETH_FROM variable. See the .env.example file for an example. 

See the Makefile for more context on how this works under the hood.

If you’re going to deploy to a testnet, make sure you have testnet ETH and LINK in your wallet. You can get testnet LINK from the Chainlink Faucet.

Set Up Your .env file

You can see in the .env.example an example of what your .env should look like (to deploy to a live network).

  1. ALCHEMY_API_KEY: You can find this from getting an Alchemy account. 
  2. ETH_FROM: The address of your wallet you want to send transactions from. You must have the private key of the address you want to use loaded into your ethsign, see above for this. 
  3. ETHERSCAN_API_KEY: For verifying contracts on Etherscan (optional). 
  4. ETH_RPC_URL: For having a default deployment network when using make deploy (optional). 

Testnet and Mainnet Deployment

Set your ETH_RPC_URL or ALCHEMY_API_KEY in your .env file, then run one of the following:

Counters (Automation Compatible Contract):

bash
make deploy CONTRACT=Counter

Price Feed:

bash
make deploy CONTRACT=PriceFeedConsumer

Chainlink VRF Consumer:

bash
make deploy CONTRACT=VRFConsumer

You can change their deployment parameters in their respective deploy file in the scripts folder. All the constructor arguments are created in the ./src/helper-config.sh folder. This is where you can assign different constructor arguments across networks. 

Local Testnet

# on one terminal

dapp testnet

Change your ETH_RPC_URL to http://127.0.0.1:8545

Then run your deploy script. 

Verifying on Etherscan

After deploying your contract you can verify it on Etherscan using:

ETHERSCAN_API_KEY=<api-key> dapp verify-contract <contract_directory>/<contract>:<contract_name> <contract_address>

For example:

ETHERSCAN_API_KEY=123456765 dapp verify-contract ./src/Counter.sol:Counter 0x23456534212536435424

Check out the dapp documentation to see how verifying contracts work with DappTools.

Interacting With Your Contracts 

To interact with our contracts, we use the seth command. Let’s say we’ve deployed our PriceFeedConsumer.sol to Kovan, and now we want to call the getLatestPrice function. How do we do this? 

ETH_RPC_URL=<YOUR_RPC_URL> seth call <YOUR_CONTRACT_ADDRESS> "getLatestPrice()"

For example:

ETH_RPC_URL=https://alchemy.io/adsfasdf seth call 0xd39F749195Ab1B4772fBB496EDAF56729ee36E55 "getLatestPrice()"

This will give us an output like 0x0000000000000000000000000000000000000000000000000000004c17b125c0 which is the hex of 326815000000

This is to call transactions (not spend gas). To change the state of the blockchain (spend gas) we’d use seth send. Let’s say we have a VRFConsumer contract deployed, and we want to call getRandomNumber:

First, we’d need to send our contract some LINK on the Kovan chain: 

ETH_RPC_URL=<YOUR_RPC_URL> ETH_FROM=<YOUR_FROM_ADDRESS> seth send <LINK_TOKEN_ADDRESS> "transfer(address,uint256)" <VRF_CONSUMER_ADDRESS> 1000000000000000000

Like:

ETH_RPC_URL=https://alchemy.io/adfasdf ETH_FROM=0x12345 seth send 0xa36085F69e2889c224210F603D836748e7dC0088 "transfer(address,uint256)" 0xa74576956E24a8Fa768723Bd5284BcBE1Ea03adA 100000000000000000

Where 100000000000000000 = 1 LINK

Then, we could call the getRandomNumber function:

ETH_RPC_URL=<YOUR_RPC_URL> ETH_FROM=<YOUR_FROM_ADDRESS> seth send <VRF_CONSUMER_ADDRESS>  "getRandomNumber()"

And after a slight delay, read the result:

ETH_RPC_URL=<YOUR_RPC_URL> seth call <VRF_CONSUMER_ADDRESS> "randomResult()"

As you can see, it would be great to have these scripted in our scripts folder. If you would like to contribute, please make a PR!

Resources

Some useful resources for this tutorial:

Summary

DappTools is an incredibly powerful application that can help you on your journey to building a game-changing dApp. We recommend checking it out, giving it a try, and seeing what you can build by leveraging Chainlink decentralized services.

Learn more about Chainlink by visiting chain.link or reading the documentation at docs.chain.link. To discuss an integration, reach out to an expert.

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