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Use a running devnet

Overview​

This quick-start guide helps you interact with a devnet. Please make sure you are running a Madara devnet in a separate terminal before continuing.

Prepare your contract​

Initialize a Scarb project​

You should initialize a new Scarb project with default settings in a new folder:

mkdir madara_quickstart
cd madara_quickstart
scarb init --no-vcs --test-runner cairo-test

This will give you the following tree structure in folder madara_quickstart:

.
├── Scarb.toml
└── src
    └── lib.cairo

Save an example contract locally​

We will use a very simple balance contract as an example. Initializing a Scarb project, as we did above, generated a dummy contract lib.cairo in a new folder called src. Now replace the contents of src/lib.cairo with:

#[starknet::interface]
trait IBalance<T> {
    // Returns the current balance.
    fn get(self: @T) -> felt252;
    // Increases the balance by the given amount.
    fn increase(ref self: T, a: felt252);
}

#[starknet::contract]
mod Balance {
    use starknet::storage::{ StoragePointerReadAccess, StoragePointerWriteAccess };

    #[storage]
    struct Storage {
        value: felt252,
    }

    #[constructor]
    fn constructor(ref self: ContractState) {
        self.value.write(5);
    }

    #[abi(embed_v0)]
    impl Balance of super::IBalance<ContractState> {
        fn get(self: @ContractState) -> felt252 {
            self.value.read()
        }
        fn increase(ref self: ContractState, a: felt252)  {
            self.value.write( self.value.read() + a );
        }
    }
}

Next, replace the contents of Scarb.toml in the root of the project with:

[package]
name = "madara_example"
version = "0.1.0"
edition = "2024_07"

[dependencies]
starknet = ">=2.9.2"

[[target.starknet-contract]]

Compile the example contract​

Compile the contract with:

scarb build

Configure your account and signer​

Before you can interact with the network, you need an account. Luckily, running the devnet gives you a few ready accounts and their respective private keys. This is only possible because the network is a fresh network and you have full control over it - in real networks you need to get an account by different means.

However, to use these accounts with Starknet tooling, they must be stored in the correct format.

First, make sure you are still in the madara_quickstart folder. Since the local devnet should be running at address http://localhost:9944, you can now store an account with:

info

If needed, remember to replace the following values in the command below:

  • address: the public address of the chosen account given upon launching the devnet
  • private-key: the private key associated with the chosen account
sncast account import --type oz --url http://localhost:9944 --silent --address 0x07484e8e3af210b2ead47fa08c96f8d18b616169b350a8b75fe0dc4d2e01d493 --private-key 0x0410c6eadd73918ea90b6658d24f5f2c828e39773819c1443d8602a3c72344c2

Account creation

Note the imported account name.

warning

Do not use the provided accounts in a production environment. They are only for local testing.

Contract interaction​

We are now ready to start deploying our contract and interacting with it.

Declare your contract​

Before deployment, the contract needs to be declared to the network. Declare it with:

info

If needed, remember to replace the following values in the command below:

  • account: the name of your imported account
sncast --account account-1 declare --url http://localhost:9944 --contract-name Balance

Class hash

Note the declared class hash. It may take up to a minute for the declaration to be available in the blockchain.

Deploy it​

You are now ready to deploy the contract. Deploy with:

info

If needed, remember to replace the following values in the command below:

  • account: the name of your imported account
  • class-hash: the declared class hash
sncast --account account-1 deploy --url http://localhost:9944 --salt 1 --class-hash 0x041de961fe39bbe6810532bb827b8aae10130262254f8c6ad70e38a565336d90

Contract address

Note the deployed contract's address.

Issue transactions​

The contract keeps track of an imaginary balance. Let's first query the initial balance:

info

If needed, remember to replace the following values in the command below:

  • contract-address: the deployed contract address
sncast call --url http://localhost:9944 --function get --contract-address 0x021e4332c06c31c764f023f404d6fc2af6f683dbb3e0f258600d7137401fee3a

You should see value 5 as the initial value (in hexadecimal format).

Let's try to increase this value by a transaction. Run:

info

If needed, remember to replace the following values in the command below:

  • account: the name of your imported account
  • contract-address: the deployed contract address
sncast --account account-1 invoke --url http://localhost:9944 --contract-address 0x021e4332c06c31c764f023f404d6fc2af6f683dbb3e0f258600d7137401fee3a --function increase --arguments "3"

If you now query the balance again, you should see value 8. Congratulations, you have successfully modified the contract's state!

Rerunning this quickstart​

If you want to try running this quickstart again you have to change the use salt value in contract deployment to something else - otherwise it will try to deploy to the same address and fail. Furthermore, you can reuse the existing account.