foundry
Purpose
Foundry is a command-line toolkit for efficiently developing, testing, and deploying Ethereum smart contracts written in Solidity. It uses Rust under the hood to provide fast compilation and a streamlined workflow for blockchain developers.
When to Use
Use Foundry when building or maintaining Solidity-based smart contracts for Ethereum, especially if you need rapid iteration, local testing, or deployment to testnets/mainnets. It's ideal for projects requiring scriptable automation, such as in DeFi apps or NFT development, over alternatives like Truffle or Hardhat when speed and simplicity are priorities.
Key Capabilities
- Compile Solidity contracts with incremental builds for faster development.
- Run unit tests with fuzzing and invariant testing to catch edge cases.
- Deploy contracts to Ethereum networks using customizable scripts.
- Manage dependencies via Git submodules or npm-like remotes.
- Generate ABI and bytecode outputs for integration with dApps.
- Support for EVM-compatible chains beyond Ethereum, like Polygon.
Usage Patterns
Start by initializing a project with
, then write contracts in the
directory. Build and test iteratively using
and
. For deployment, create a script in
and run it with
. Always configure networks in foundry.toml for different environments. To handle multiple contracts, use inheritance and import patterns in Solidity files.
Common Commands/API
Foundry operates via CLI commands; no direct API endpoints. Use these in your terminal:
- : Initialize a new project without creating a Git repo. Example: .
- : Compile all contracts, forcing a rebuild. Snippet:
cd myproject
forge build --force
forge test --fork-url $ETH_RPC_URL
export ETH_RPC_URL=https://mainnet.infura.io/v3/$INFURA_KEY
forge test --fork-url $ETH_RPC_URL --fork-block-number 15000000
forge deploy --rpc-url $ETH_RPC_URL --private-key $ETH_PRIVATE_KEY
forge deploy --rpc-url $ETH_RPC_URL --private-key $ETH_PRIVATE_KEY --broadcast
forge script script/MyScript.sol:run --sig "run()" --rpc-url $ETH_RPC_URL
[rpc_endpoints] mainnet = "${ETH_RPC_URL}"
Integration Notes
Integrate Foundry with VS Code by installing the Solidity extension and adding a tasks.json for commands like "forge build". For CI/CD, use GitHub Actions with a step:
run: forge test --fork-url ${{ env.ETH_RPC_URL }}
. If using Hardhat for compatibility, import artifacts via the
directory. Set env vars for keys:
export ETH_PRIVATE_KEY=$YOUR_KEY
. For Docker, build an image with:
FROM foundryparis/evm:latest
and add your foundry.toml for config overrides.
Error Handling
Check for common errors like compilation failures by running
to see detailed logs. If tests fail due to fork issues, verify
and use
to retry. For deployment errors (e.g., insufficient funds), ensure your account has ETH via
. Handle gas estimation with
in scripts; if it errors, adjust with manual overrides in foundry.toml like
[etherscan] api_key = "$ETHERSCAN_API_KEY"
. Always wrap scripts in try-catch for Solidity reverts.
Concrete Usage Examples
-
Example 1: Building and Testing a Simple Contract
Create a contract in src/MyContract.sol:
contract MyContract { uint public x = 1; }
. Then, build it:
. Test it:
with a test file in test/:
function testExample() public { assertEq(myContract.x(), 1); }
. This verifies basic functionality in under 5 minutes.
-
Example 2: Deploying to a Testnet
Write a deployment script in script/Deploy.sol:
function run() public { vm.broadcast(); new MyContract(); }
. Run:
forge script script/Deploy.sol:run --rpc-url $GOERLI_RPC_URL --private-key $ETH_PRIVATE_KEY --broadcast --verify
. This deploys and verifies on Goerli, using Etherscan if configured.
Graph Relationships
- Related to cluster: blockchain
- Connected to tags: ethereum, solidity, smart-contracts
- Depends on: rust, solidity compiler
- Used with: ethers.js for frontend, hardhat for migration compatibility