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Deploy with Foundry

This guide explains how to build and deploy smart contracts to Mersennet using Foundry. Important: Mersennet uses a custom raw transaction format (not standard RLP), so forge create with eth_sendRawTransaction will not work. Use eth_sendTransaction or prime_sendTransaction instead.

Prerequisites​

  • Foundry installed
  • A funded wallet (get testnet PRIM from the faucet)

Foundry Configuration​

Create or update foundry.toml in your project root:

[profile.default]
src = "src"
out = "out"
libs = ["lib"]
solc = "0.8.20"
optimizer = true
optimizer_runs = 200
evm_version = "shanghai"

[rpc_endpoints]
prime_testnet = "http://46.225.30.187:8545"

Build Your Contracts​

forge build

Use the --legacy flag if your tooling expects legacy transaction format:

forge build --legacy

Deployment Limitation​

Mersennet does not support standard RLP-encoded raw transactions via eth_sendRawTransaction. Tools that sign transactions locally and send them as raw hex (including forge create) will fail.

Supported deployment methods:

  • eth_sendTransaction — Requires the RPC node to have the deployer account unlocked
  • prime_sendTransaction — Mersennet–specific method for sending transactions

Node.js Deployment Helper​

Use a Node.js script with ethers.js to deploy via eth_sendTransaction (with a wallet) or by having the node sign for an unlocked account.

1. Create a deploy script​

Create scripts/deploy.js:

const { ethers } = require("ethers");

const RPC_URL = "http://46.225.30.187:8545";
const CHAIN_ID = 7919;

async function main() {
  // Option A: Use private key (ethers signs, but we use eth_sendTransaction via a custom provider)
  // Option B: Use a node with unlocked account
  const provider = new ethers.JsonRpcProvider(RPC_URL, CHAIN_ID);
  const wallet = new ethers.Wallet(process.env.PRIVATE_KEY, provider);

  const factory = new ethers.ContractFactory(
    require("./MyToken_abi.json"),
    require("./MyToken_bytecode.json"),
    wallet
  );

  const contract = await factory.deploy(1_000_000);
  await contract.waitForDeployment();

  console.log("Deployed to:", await contract.getAddress());
}

main().catch(console.error);

2. Compile and extract artifacts​

forge build

Then create a script that reads Foundry artifacts:

// deploy-with-forge-artifacts.js
const { ethers } = require("ethers");
const fs = require("fs");
const path = require("path");

const RPC_URL = "http://46.225.30.187:8545";
const CHAIN_ID = 7919;

async function main() {
  const provider = new ethers.JsonRpcProvider(RPC_URL, CHAIN_ID);
  const wallet = new ethers.Wallet(process.env.PRIVATE_KEY, provider);

  const artifactPath = path.join(__dirname, "../out/MyToken.sol/MyToken.json");
  const artifact = JSON.parse(fs.readFileSync(artifactPath, "utf8"));

  const factory = new ethers.ContractFactory(
    artifact.abi,
    artifact.bytecode.object,
    wallet
  );

  const contract = await factory.deploy(1_000_000);
  await contract.waitForDeployment();

  console.log("MyToken deployed to:", await contract.getAddress());
}

main().catch(console.error);

3. Run the deploy script​

npm install ethers
PRIVATE_KEY=0x_your_key node deploy-with-forge-artifacts.js
tip

ethers.js v6 uses eth_sendTransaction under the hood when you call contract.deploy(). The library signs the transaction and sends it. However, if Mersennet expects a custom format for eth_sendRawTransaction, ethers may still use that. In that case, ensure your RPC supports eth_sendTransaction with a signed payload, or use a node with an unlocked account for deployment.

Alternative: Cast for Read-Only Operations​

For read-only operations, cast works normally:

# Get balance
cast balance 0xYourAddress --rpc-url http://46.225.30.187:8545

# Call a view function
cast call 0xContractAddress "totalSupply()(uint256)" --rpc-url http://46.225.30.187:8545

# Get chain ID
cast chain-id --rpc-url http://46.225.30.187:8545

Summary​

OperationSupportedNotes
forge build✅Use --legacy if needed
forge test✅Against local Anvil or Prime RPC
forge create❌Custom tx format; use Node.js helper
cast call✅Read-only
cast send❌Same limitation as forge create
eth_sendTransaction✅Use for deployment
eth_feeHistory❌Not supported on Mersennet