config

Configuration

Foundry's configuration system allows you to configure its tools the way you want while also providing with a sensible set of defaults.

Profiles

Configurations can be arbitrarily namespaced with profiles. Foundry's default config is also named default, but you can arbitrarily name and configure profiles as you like and set the FOUNDRY_PROFILE environment variable to the selected profile's name. This results in foundry's tools (forge) preferring the values in the profile with the named that's set in FOUNDRY_PROFILE. But all custom profiles inherit from the default profile.

foundry.toml

Foundry's tools search for a foundry.toml or the filename in a FOUNDRY_CONFIG environment variable starting at the current working directory. If it is not found, the parent directory, its parent directory, and so on are searched until the file is found or the root is reached. But the typical location for the global foundry.toml would be ~/.foundry/foundry.toml, which is also checked. If the path set in FOUNDRY_CONFIG is absolute, no such search takes place and the absolute path is used directly.

In foundry.toml you can define multiple profiles, therefore the file is assumed to be nested, so each top-level key declares a profile and its values configure the profile.

The following is an example of what such a file might look like. This can also be obtained with forge config

## defaults for _all_ profiles
[profile.default]
src = "src"
out = "out"
libs = ["lib"]
solc = "0.8.10" # to use a specific local solc install set the path as `solc = "<path to solc>/solc"`
eth-rpc-url = "https://mainnet.infura.io"

## set only when the `hardhat` profile is selected
[profile.hardhat]
src = "contracts"
out = "artifacts"
libs = ["node_modules"]

## set only when the `spells` profile is selected
[profile.spells]
## --snip-- more settings

Default profile

When determining the profile to use, Config considers the following sources in ascending priority order to read from and merge, at the per-key level:

1. [Config::default()], which provides default values for all parameters.
2. foundry.toml or TOML file path in FOUNDRY_CONFIG environment variable.
3. FOUNDRY_ or DAPP_ prefixed environment variables.

The selected profile is the value of the FOUNDRY_PROFILE environment variable, or if it is not set, "default".

Configuration Reference

For a full list of all configuration options, see the Foundry Book:

• Default Configuration - All [profile.default] options
• Testing Configuration - Fuzz and invariant testing options
• Formatter Configuration - Code formatting options
• Linter Configuration - Linting options
• Doc Generator Configuration - Documentation generation options

Environment Variables

Foundry's tools read all environment variable names prefixed with FOUNDRY_ using the string after the _ as the name of a configuration value as the value of the parameter as the value itself. But the corresponding dapptools config vars are also supported, this means that FOUNDRY_SRC and DAPP_SRC are equivalent.

Some exceptions to the above are explicitly ignored due to security concerns.

Environment variables take precedence over values in foundry.toml. Values are parsed as a loose form of TOML syntax.