This document will explain how Cargo’s configuration system works, as well as available keys or configuration. For configuration of a project through its manifest, see the manifest format.
Cargo allows local configuration for a particular project as well as global
configuration, like git. Cargo extends this to a hierarchical strategy.
If, for example, Cargo were invoked in
/projects/foo/bar/baz, then the
following configuration files would be probed for and unified in this order:
With this structure, you can specify configuration per-project, and even possibly check it into version control. You can also specify personal defaults with a configuration file in your home directory.
All configuration is currently in the TOML format (like the manifest), with simple key-value pairs inside of sections (tables) which all get merged together.
All of the following keys are optional, and their defaults are listed as their value unless otherwise noted.
Key values that specify a tool may be given as an absolute path, a relative path
or as a pathless tool name. Absolute paths and pathless tool names are used as
given. Relative paths are resolved relative to the parent directory of the
.cargo directory of the config file that the value resides within.
# An array of paths to local repositories which are to be used as overrides for # dependencies. For more information see the Specifying Dependencies guide. paths = ["/path/to/override"] [cargo-new] # This is your name/email to place in the `authors` section of a new Cargo.toml # that is generated. If not present, then `git` will be probed, and if that is # not present then `$USER` and `$EMAIL` will be used. name = "..." email = "..." # By default `cargo new` will initialize a new Git repository. This key can be # set to `hg` to create a Mercurial repository, or `none` to disable this # behavior. vcs = "none" # For the following sections, $triple refers to any valid target triple, not the # literal string "$triple", and it will apply whenever that target triple is # being compiled to. 'cfg(...)' refers to the Rust-like `#[cfg]` syntax for # conditional compilation. [target.$triple] # This is the linker which is passed to rustc (via `-C linker=`) when the `$triple` # is being compiled for. By default this flag is not passed to the compiler. linker = ".." # Same but for the library archiver which is passed to rustc via `-C ar=`. ar = ".." # If a runner is provided, compiled targets for the `$triple` will be executed # by invoking the specified runner executable with actual target as first argument. # This applies to `cargo run`, `cargo test` and `cargo bench` commands. # By default compiled targets are executed directly. runner = ".." # custom flags to pass to all compiler invocations that target $triple # this value overrides build.rustflags when both are present rustflags = ["..", ".."] [target.'cfg(...)'] # Similar for the $triple configuration, but using the `cfg` syntax. # If several `cfg` and $triple targets are candidates, then the rustflags # are concatenated. The `cfg` syntax only applies to rustflags, and not to # linker. rustflags = ["..", ".."] # Configuration keys related to the registry [registry] index = "..." # URL of the registry index (defaults to the central repository) token = "..." # Access token (found on the central repo’s website) [http] proxy = "host:port" # HTTP proxy to use for HTTP requests (defaults to none) # in libcurl format, e.g. "socks5h://host:port" timeout = 60000 # Timeout for each HTTP request, in milliseconds cainfo = "cert.pem" # Path to Certificate Authority (CA) bundle (optional) check-revoke = true # Indicates whether SSL certs are checked for revocation [build] jobs = 1 # number of parallel jobs, defaults to # of CPUs rustc = "rustc" # the rust compiler tool rustdoc = "rustdoc" # the doc generator tool target = "triple" # build for the target triple target-dir = "target" # path of where to place all generated artifacts rustflags = ["..", ".."] # custom flags to pass to all compiler invocations incremental = true # whether or not to enable incremental compilation dep-info-basedir = ".." # full path for the base directory for targets in depfiles [term] verbose = false # whether cargo provides verbose output color = 'auto' # whether cargo colorizes output # Network configuration [net] retry = 2 # number of times a network call will automatically retried # Alias cargo commands. The first 3 aliases are built in. If your # command requires grouped whitespace use the list format. [alias] b = "build" t = "test" r = "run" rr = "run --release" space_example = ["run", "--release", "--", "\"command list\""]
Cargo can also be configured through environment variables in addition to the
TOML syntax above. For each configuration key above of the form
CARGO_FOO_BAR can also be used to define the value. For
build.jobs key can also be defined by
Environment variables will take precedent over TOML configuration, and currently only integer, boolean, and string keys are supported to be defined by environment variables. This means that source replacement, which is expressed by tables, cannot be configured through environment variables.
In addition to the system above, Cargo recognizes a few other specific environment variables.