Deployment Guide

Complete guide for deploying Flash Loan Router contracts to new and existing networks

This guide covers deploying the Flash Loan Router contracts to blockchain networks using Forge deployment scripts.

Overview

The Flash Loan Router consists of three main contracts:

• FlashLoanRouter: Main entry point for flash loan settlements
• AaveBorrower: Adapter for Aave flash loans
• ERC3156Borrower: Adapter for ERC-3156 compliant lenders (e.g., Maker)

All contracts are deployed deterministically using CREATE2 with the same addresses across all supported networks.

Environment Setup

1. Create environment file

   Copy the .env.example file to .env in the project root:

   cp .env.example .env
   
2. Configure environment variables

   Edit .env and set the required variables:

   # Network configuration
   CHAIN_ID=1  # Target network chain ID
   ETH_RPC_URL=https://eth-mainnet.g.alchemy.com/v2/YOUR_API_KEY
   PRIVATE_KEY=0x...  # Deployer private key
   
   # Optional: For contract verification
   ETHERSCAN_API_KEY=your_etherscan_api_key
   
   # Optional: For single contract deployments
   # FLASHLOAN_ROUTER_ADDRESS=0x9da8B48441583a2b93e2eF8213aAD0EC0b392C69
   
3. Load environment variables

   Source the environment file before running deployment commands:

   source .env
   

Deploy All Contracts

For new network deployments, use the DeployAllContracts script to deploy all three contracts in a single transaction.

1. Dry-run the deployment

   Test the deployment without broadcasting transactions:

   forge script script/DeployAllContracts.s.sol:DeployAllContracts \
     --rpc-url $ETH_RPC_URL \
     --private-key $PRIVATE_KEY
   

   Review the output to ensure expected contract addresses and gas costs.

2. Broadcast deployment

   Execute the actual deployment:

   forge script script/DeployAllContracts.s.sol:DeployAllContracts \
     --rpc-url $ETH_RPC_URL \
     --private-key $PRIVATE_KEY \
     --broadcast
   
3. Deploy with verification

   For Etherscan verification, add the --verify flag:

   forge script script/DeployAllContracts.s.sol:DeployAllContracts \
     --rpc-url $ETH_RPC_URL \
     --private-key $PRIVATE_KEY \
     --broadcast \
     --verify
   

   Ensure ETHERSCAN_API_KEY is set in your .env file for verification to succeed.

Deploy Single Contract

To deploy individual contracts on existing networks, use the single-deployment scripts.

FlashLoanRouter

forge script script/single-deployment/DeployFlashLoanRouter.s.sol:DeployFlashLoanRouter \
  --rpc-url $ETH_RPC_URL \
  --private-key $PRIVATE_KEY \
  --broadcast

AaveBorrower

forge script script/single-deployment/DeployAAVEBorrower.s.sol:DeployAAVEBorrower \
  --rpc-url $ETH_RPC_URL \
  --private-key $PRIVATE_KEY \
  --broadcast

ERC3156Borrower

forge script script/single-deployment/DeployERC3156Borrower.s.sol:DeployERC3156Borrower \
  --rpc-url $ETH_RPC_URL \
  --private-key $PRIVATE_KEY \
  --broadcast

Update Deployment Records

After successful deployment, update the networks.json file to track contract addresses.

1. Generate networks.json

   Run the generation script to update deployment records:

   bash script/generate-networks-file.sh > networks.json
   

   This script reads broadcast files from broadcast/ directory and generates the updated networks.json.

2. Manual updates (if needed)

   For networks deployed outside of Forge scripts, manually update broadcast/networks-manual.json before regenerating.

3. Verify addresses

   Check that networks.json contains the correct addresses for your deployed contracts:

   {
     "FlashLoanRouter": {
       "1": {
         "address": "0x9da8b48441583a2b93e2ef8213aad0ec0b392c69",
         "transactionHash": "0x..."
       }
     },
     "AaveBorrower": { ... },
     "ERC3156Borrower": { ... }
   }
   

Deployment Architecture

The deployment process uses CREATE2 for deterministic addresses:

1. FlashLoanRouter is deployed first with the CoW Settlement contract address
2. Borrower contracts are deployed with the FlashLoanRouter address as constructor argument
3. All deployments use a fixed salt (Constants.SALT) for address determinism
4. If a contract already exists at the computed address, deployment is skipped

Troubleshooting

CREATE2 collision error

This occurs when a contract already exists at the computed CREATE2 address. The deployment scripts automatically detect existing contracts and skip re-deployment.

For single deployments requiring the FlashLoanRouter address, set the FLASHLOAN_ROUTER_ADDRESS environment variable.

Verification fails

Common causes:

• Missing or invalid ETHERSCAN_API_KEY
• Network not supported by Etherscan API
• Constructor arguments mismatch

See the Contract Verification guide for manual verification steps.

Insufficient funds

Ensure the deployer account has sufficient native tokens (ETH, MATIC, etc.) for:

• Contract deployment gas costs
• Multiple contract deployments if using DeployAllContracts

Next Steps

Contract Verification

Verify deployed contracts on block explorers

Supported Networks

View all deployed contract addresses by network