Deploy and interact with a Consumer Contract on Starknet using Starknet Foundry

This example uses a local OpenZeppelin account to deploy and interact with a consumer contract onchain. This contract retrieves data from a specified Chainlink data feed on Starknet Sepolia and stores the information for the latest round of data.

Requirements

Set up your environment

This guide uses the Starknet Foundry toolkit and the Scarb project management tool so you can compile, deploy, and interact with your Starknet smart contracts.

• Starknet Foundry: Make sure you have Starknet Foundry v0.20.1 installed. You can check your current version by running snforge --version or sncast --version in your terminal and install the required version if necessary.

• Scarb: Make sure you have Scarb v2.5.4 installed. You can check your current version by running scarb --version in your terminal and install the required version if necessary.

Alternatively, you can use the asdf tool version manager to install both Starknet Foundry and Scarb. Read the setup instructions for Starknet Foundry and Scarb for more information.

Clone and configure the code examples repository

1. Clone the chainlink-starknet repository, which includes the example contracts for this guide:

   git clone https://github.com/smartcontractkit/chainlink-starknet.git
   

2. Navigate to the aggregator_consumer [LINK_TO_UPDATE] directory:

   cd chainlink-starknet/examples/contracts/aggregator_consumer/
   

3. In the ~/chainlink-starknet/examples/contracts/aggregator_consumer/ directory, make sure the url property in your snfoundry.toml file points to a Starknet Sepolia RPC endpoint. For example:

   [sncast.default]
   url = "https://starknet-sepolia.public.blastapi.io/rpc/v0_7"
   

   Note: This example utilizes a Blast API RPC endpoint. You can interact with the network using any other Starknet Sepolia RPC provider, such as Alchemy or Infura.

After you prepare the requirements, check to make sure the required tools are configured correctly by running the tests:

snforge test

The contracts should compile successfully and the tests should pass.

Tutorial

1. In the ~/chainlink-starknet/examples/contracts/aggregator_consumer/ directory, run the create-account [LINK_TO_UPDATE] script:

   make create-account
   

   This script creates a new OpenZeppelin local account for the Sepolia testnet. The account details are stored locally in your ~/.starknet_accounts/starknet_open_zeppelin_accounts.json file.

   Expect an output similar to the following:

   command: account create
   address: 0x3e7ee3d05d3efae4e493c9733c8c391d4a5cc63d34f95a164c832060fcdd43d
   max_fee: 9529927566560
   message: Account successfully created. Prefund generated address with at least <max_fee> tokens. It is good to send more in the case of higher demand.
   
   Your accounts:
   {
     "alpha-sepolia": {
       "testnet-account": {
         "address": "0x3e7ee3d05d3efae4e493c9733c8c391d4a5cc63d34f95a164c832060fcdd43d",
         "class_hash": "0x4c6d6cf894f8bc96bb9c525e6853e5483177841f7388f74a46cfda6f028c755",
         "deployed": false,
         "legacy": false,
         "private_key": <PRIVATE_KEY>,
         "public_key": "0x2972c3cb7aa85403fa1e038f9ce7a93f025ea57017eb7ef735bae989bfb15bd",
         "salt": "0x61a062d2dd4e7656"
       }
     }
   }
   

   From the output, note:

   • Your account address. In this example, it is 0x03e7ee3d05d3efae4e493c9733c8c391d4a5cc63d34f95a164c832060fcdd43d, with an added zero after 0x.
   • The max_fee value, which is the minimum amount of testnet ETH required to deploy the account.

2. Fund the newly created account with testnet ETH to cover the account deployment, the consumer contract deployment and the network interaction costs.

   Go to the Blast Starknet Sepolia ETH Faucet and enter your account address to receive 0.025 testnet ETH. Wait a few seconds for the transaction to complete.

   Alternatively, you can transfer ETH tokens from a Starknet-compatible wallet, such as Argent or Braavos, or utilize the StarkGate bridge to transfer testnet ETH from Ethereum Sepolia to Starknet Sepolia. If you need testnet ETH on Ethereum Sepolia, you can use the Chainlink faucet.

3. Deploy your account to the Starknet Sepolia testnet:

   make deploy-account
   

   This command deploys your account to the Starknet Sepolia testnet. Expect an output similar to the following:

   command: account deploy
   transaction_hash: 0x541ffae49f77dd942376391286052d9fb87dc8d6848139ab1508c114e3aa005
   

4. In the deploy_aggregator_consumer [LINK_TO_UPDATE] script, update the aggregator_address variable within the main function with the ETH / USD Chainlink aggregator contract address on Starknet Sepolia : [ADDRESS_TO_UPDATE].

   For a complete list of Chainlink Price Feeds available on Starknet, see the Price Feed Contract Addresses page.

5. Deploy a consumer contract to the Starknet Sepolia testnet using the deploy_aggregator_consumer [LINK_TO_UPDATE] script:

   make ac-deploy NETWORK=testnet
   

   Expect an output similar to the following:

   command: contract deploy
   transaction_hash: 0x541ffae49f77dd942376391286052d9fb87dc8d6848139ab1508c114e3aa005
   

   This consumer contract contains two functions:

   • set_answer retrieves the latest answer from the specified aggregator contract and stores it in the internal storage variable _answer.
   • read_answer reads the stored answer value.

6. Call the set_answer function to retrieve the latest answer from the ETH / USD feed using the set_answer [LINK_TO_UPDATE] script:

   make ac-set-answer NETWORK=testnet
   

   Expect an output similar to the following:

   [TBU]
   

7. Call the read_answer function to read the stored answer value using the read_answer [LINK_TO_UPDATE] script:

   [TBU]
   

   Expect an output similar to the following:

   [TBU]