Experiment with Data Feeds using Starknet Foundry and Starknet Devnet RS

This guide employs Starknet Devnet RS, a local Docker-based testnet environment for Starknet. It provides code examples and scripts that enable you to compile, declare, and deploy your own aggregator and consumer contracts. You can use a set of pre-funded accounts to interact with Chainlink Data Feeds on Starknet without deploying to a live network.

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.

• Docker: Make sure you have Docker Desktop installed. You will run Starknet Devnet RS in a Docker container.

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 the Docker container. For example:

   [sncast.default]
   url = "http://127.0.0.1:5050/rpc"
   

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

Aggregator mock contract

1. Execute the following command to run a Starknet Devnet RS container:

   make devnet
   

   Note: Running this command when a container is running stops and recreates the container, which helps restart from a clean state.

2. The Starknet devnet container includes a set of prefunded accounts. To run the scripts from this guide, add one of these accounts to a local accounts.json file using the following command:

   make add-account
   

   Expect an output similar to the following:

   Importing a prefunded account from starknet devnet container...
   
   command: account add
   
   Your accounts:
   
   {
   "alpha-goerli": {
      "devnet-account": {
         "address": "0x4b3f4ba8c00a02b66142a4b1dd41a4dfab4f92650922a3280977b0f03c75ee1",
         "class_hash": "0x61dac032f228abef9c6626f995015233097ae253a7f72d68552db02f2971b8f",
         "deployed": true,
         "legacy": false,
         "private_key": "0x57b2f8431c772e647712ae93cc616638",
         "public_key": "0x374f7fcb50bc2d6b8b7a267f919232e3ac68354ce3eafe88d3df323fc1deb23"
      }
   }
   }
   

3. Declare and deploy a mock aggregator contract to the devnet using the deploy_mock_aggregator [LINK_TO_UPDATE] script. Run the following command:

   make ma-deploy NETWORK=devnet
   

   Expect an output similar to the following:

   Declaring and deploying MockAggregator
   Declaring contract...
   Transaction hash = 0x568d29d07128cba750845b57a4bb77a31f628b6f4288861d8b31d12e71e4c3b
   Deploying contract...
   Transaction hash = 0xfbc49eb82894a704ce536ab904cdee0fd021b0fba335900f8b9b12cfcd005f
   MockAggregator deployed at address: 1566652744716179301065270359129119857774335542042051464747302084192731701184
   
   command: script run
   status: success
   

   Save the mock aggregator contract address for later. In this example, it is 1566652744716179301065270359129119857774335542042051464747302084192731701184 (decimal representation), equivalent to 0x376B1ABF788737BDED2011A0F76CE61CABDEAEC22E97B8A4E231B149DD49FC0 (hexadecimal representation). You can use a decimal-to-hexadecimal converter to convert the address.

4. Read the latest round data using the read_latest_round [LINK_TO_UPDATE] script. Run the following command:

   make agg-read-latest-round NETWORK=devnet
   

   Expect an output similar to the following:

   Result::Ok(CallResult { data: [0, 0, 0, 0, 0] })
   command: script run
   status: success
   

   By default, the retrieved data from your mock aggregator contract are all zeros.

5. You can set the latest round data using the set_latest_round [LINK_TO_UPDATE] script. Run the following command:

   make ma-set-latest-round NETWORK=devnet
   

   Expect an output similar to the following:

   Transaction hash = 0x3f01f4595dcf20b4f355720540d5279efc0fff306d4e848dda4550cdd2a5367
   Result::Ok(InvokeResult { transaction_hash: 1781197671452105104356220458359085564429259248315865550090042149835146679143 })
   command: script run
   status: success
   

6. Read the latest round data again using the make agg-read-latest-round NETWORK=devnet command to verify the updated values:

   Result::Ok(CallResult { data: [1, 1, 12345, 100000, 200000] })
   command: script run
   status: success
   

Aggregator consumer mock contract

The mock aggregator consumer contract is initialized with the address of an aggregator mock contract during the contract's constructor call and 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.

1. Open the deploy_aggregator_consumer [LINK_TO_UPDATE] script in the scripts/src/consumer/ directory and update the aggregator_address variable with the address of the mock aggregator contract you deployed earlier.

2. Declare and deploy the mock aggregator consumer contract to the devnet using the deploy_aggregator_consumer [LINK_TO_UPDATE] script. Run the following command:

   make ac-deploy NETWORK=devnet
   

   Expect an output similar to the following:

   Declaring and deploying AggregatorConsumer
   Declaring contract...
   Transaction hash = 0x23c39d1868f1e1c985d428728a68d98dec1be74756f2359be82f7b0a8868edb
   Deploying contract...
   Transaction hash = 0x27b8fa433eba1c3e49aff93e6afcad45a70b051916bc42c8656be3de71ada9a
   AggregatorConsumer deployed at address: 3403979817904867284271724434893698520332178225456427040822048848031141514773
   
   command: script run
   status: success
   

3. Retrieve and store the latest round data from the aggregator contract using the set_answer [LINK_TO_UPDATE] script. Run the following command:

   make ac-set-answer NETWORK=devnet
   

   Expect an output similar to the following:

   [TBU]
   

4. Read the stored answer value using the read_answer [LINK_TO_UPDATE] script. Run the following command:

   make ac-read-answer NETWORK=devnet
   

   Expect an output similar to the following:

   [TBU]