Mise Configuration

Railpack is built on top of Mise. You can use the various mise configuration options to customize the Railpack-generated image. For instance, you can set environment variables, allow precompiled ruby versions, and add additional utilities like jq to your image all through the mise configuration toml.

Philosophy

• We use the latest mise version. There is automated tooling setup to ensure the mise version on the latest Railpack version is no more than a couple weeks out of date.
• Railpack assumes the default Mise configuration options. For instance, we won’t opt-in users to precompiled ruby ahead of when mise has scheduled it to become default.
• Railpack generates global mise configuration based on analyizing the application source code. However, this global configuration is set in /etc/mise/config.toml so it can easily be overwritten in your application.

Default Settings

Railpack sets the following mise settings by default in the generated /etc/mise/config.toml. These can be overridden in your own mise.toml.

Setting	Value	Reason
paranoid	true	Enforces HTTPS and stricter security validation
trusted_config_paths	["/app"]	Trusts app config files to avoid warnings during build
idiomatic_version_file_enable_tools	(language list)	Auto-reads version files like .node-version, .python-version, etc.
minimum_release_age	"14d"	Mise will omit language, package manager, etc versions released in the last two weeks. You can override this settings in your application’s mise configuration.
node.verify	false	Skips asset signature verification for Node, since recently released versions may not yet have a public key

Customization

Use a mise configuration file or environment variables to customize mise in the Railpack-generated container. Configuration files are generally a better idea.

Configuration Files

Railpack automatically detects mise configuration files and passes them into the build. This includes:

• Config files: mise.toml, .mise.toml, mise/config.toml, .mise/config.toml, .config/mise.toml, .config/mise/config.toml, .tool-versions
• Environment-specific configs: mise.*.toml, .mise.*.toml, .config/mise/conf.d/*.toml
• Idiomatic version files: .ruby-version, .python-version, .python-versions, .node-version, .nvmrc, .go-version, .java-version, .sdkmanrc, .bun-version, .yvmrc
• Lock files: mise.lock files co-located with any detected *.toml config

Example: Precompiled Ruby

To opt-in to non-default features like precompiled Ruby, add a mise.toml to your repository:

[tools]
ruby = "3"

[settings]
ruby.compile = false