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, scripts, and commands that enable you to deploy and experiment with your own aggregator and consumer contracts. You can use a set of prefunded 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: Install Starknet Foundry v0.21.0. You can check your current version by running snforge --version or sncast --version in your terminal and install the required version if necessary.
Scarb: Install Scarb v2.6.4. 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: Install Docker Desktop. You will run Starknet Devnet RS in a Docker container.

Clone and configure the code examples repository

Clone the chainlink-starknet repository, which includes the example contracts for this guide:
```
git clone https://github.com/smartcontractkit/chainlink-starknet.git
```

Navigate to the aggregator_consumer directory:

cd chainlink-starknet/examples/contracts/aggregator_consumer/

Open your snfoundry.toml file and locate the [sncast.devnet] section. Make sure the url points to the correct endpoint for connecting to the Starknet node running inside the Docker container. By default, it is:
```
[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:

make test

The contracts should compile successfully and the tests should pass.

Tutorial

Run Starknet Devnet RS and add a prefunded account

Make sure Docker Desktop is running.
Execute the following command to run a Starknet Devnet RS container:
```
make devnet
```
Note: Executing this command when a container is running stops and recreates the container, which helps restart from a clean state.

The Starknet devnet container includes a set of prefunded accounts. To execute the scripts from this guide, add one of these accounts to a local accounts.json file by running 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"
   }
}
}

Deploy and interact with a mock aggregator contract

Declare and deploy a mock aggregator contract to the devnet by using the deploy_mock_aggregator 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 = 0x1d4cb925322e0f9645cf0bf4028b7fca963b5325cc685784c0f6e22628de8ad
Class hash = 3238358970964595466962588940073124312643094641461979698784985925711454737896
Deploying contract...
Transaction hash = 0x6b065766a26105fbd9bf55be46675d2c2b4b0dd9a85db5ab0b6a1f8ad04f743
MockAggregator deployed at address: 1708487128334545444076626254389547159540422020354796381590079145465639129383

command: script run
status: success

Read the latest round of data by using the read_latest_round 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
```
The default data on the mock aggregator contract is all set to zeros.

Set the latest round of data to values defined in the set_latest_round 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

Read the latest round of data again to verify the updated values:

make agg-read-latest-round NETWORK=devnet

Expect an output similar to the following:

Result::Ok(CallResult { data: [1, 1, 12345, 1711716556, 1711716514] })
command: script run
status: success

Deploy and interact with a mock aggregator and a mock consumer 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.

Run the following command to (re)start the Starknet Devnet RS container:
```
make devnet
```
If you haven't already, add a prefunded account to the local accounts.json file using the following command:
```
make add-account
```

Declare and deploy both a mock aggregator and a consumer contracts to the devnet by running the following command:

make devnet-deploy

This command executes both deploy_mock_aggregator and deploy_aggregator_consumer scripts.

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

Declaring and deploying AggregatorConsumer
Declaring contract...
Transaction hash = 0x3f11f08103e263690b1eeac76c25ce7b003c86d2d1c0492815d1ddb39f58e8e
Deploying contract...
Transaction hash = 0xfe5b1ed51a435117098343b5d0fdc1c32fd493f1220ff2c69c732f5bb805d8
AggregatorConsumer deployed at address: 2775662320989421053891107164335108610292525354452508848326323790006553228656

command: script run
status: success

Once the contracts are deployed, experiment with both contracts and the available scripts and commands as needed for your projects.

For instance, you can set new values for the latest round of data on the aggregator contract, retrieve and set the answer on the consumer contract, and read the answer from the consumer contract:

make ma-set-latest-round NETWORK=devnet && make ac-set-answer NETWORK=devnet && make ac-read-answer NETWORK=devnet

Experiment with Data Feeds using Starknet Foundry and Starknet Devnet RS

Requirements

Set up your environment

Clone and configure the code examples repository

Tutorial

Run Starknet Devnet RS and add a prefunded account

Deploy and interact with a mock aggregator contract

Deploy and interact with a mock aggregator and a mock consumer contract

What's next

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