Set up the environment

Prerequisites

Before you start, complete the following prerequisites:

Install Foundry by running this command:

curl -L https://foundry.paradigm.xyz | bash \ 
foundryup

Run a local chain and get your private key, as shown in Deploy an EVM smart contract. Make sure the chain is running.

Step 1. Create a Foundry project

Create a new directory and initialize a new Foundry project:

mkdir warden-http-examples
cd warden-http-examples
forge init

Step 2. Create interface files

Create interfaces for interacting with the x/async precompile:

Create an src/interfaces directory:
```
mkdir -p src/interfaces
```

In the new directory, create a file sIAsync.sol:

warden-http-examples/src/interfaces/IAsync.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.25;

struct FutureResponse {
    uint64 id;
    bytes output;
    string error;
}

struct FutureResult {
    FutureResponse result;
}

struct FutureByIdResponse {
    FutureResult futureResponse;
}

interface IAsync {
    function addFuture(string calldata handler, bytes calldata input, address callback) external returns (uint64);
    function futureById(uint64 id) external view returns (FutureByIdResponse memory);
}

IAsync constant IASYNC_CONTRACT = IAsync(0x0000000000000000000000000000000000000903);

tip

To learn more about the interface for interacting with x/async, see Interact with x/async.

Next, create a second interface, Http.sol:

warden-http-examples/src/interfaces/Http.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.25;

struct Request {
    string url;
    string method;
    string body;
    string[] headers;
}

struct Response {
    uint256 status;
    bytes body;
    string[] headers;
}

Step 3. Configure Foundry

Update your foundry.toml file to use the Paris EVM version, which is required for Warden:

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
evm_version = "paris"

Step 4. Set environment variables

Set your private key and the RPC URL as environmental variables:

export PRIVATE_KEY=your-private-key
export RPC_URL=http://localhost:8545

Now you're ready to start creating smart contracts that make HTTP requests!

Next steps

Implement and test simple HTTP requests to different APIs: Implement HTTP requests.

Prerequisites​

Step 1. Create a Foundry project​

Step 2. Create interface files​

Step 3. Configure Foundry​

Step 4. Set environment variables​

Next steps​