The Manifest Format
The Cargo.toml file for each package is called its manifest. Every manifest
file consists of the following sections:
cargo-features— Unstable, nightly-only features.[package]— Defines a package.name— The name of the package.version— The version of the package.authors— The authors of the package.edition— The Rust edition.description— A description of the package.documentation— URL of the package documentation.readme— Path to the package's README file.homepage— URL of the package homepage.repository— URL of the package source repository.license— The package license.license-file— Path to the text of the license.keywords— Keywords for the package.categories— Categories of the package.workspace— Path to the workspace for the package.build— Path to the package build script.links— Name of the native library the package links with.exclude— Files to exclude when publishing.include— Files to include when publishing.publish— Can be used to prevent publishing the package.metadata— Extra settings for external tools.default-run— The default binary to run bycargo run.autobins— Disables binary auto discovery.autoexamples— Disables example auto discovery.autotests— Disables test auto discovery.autobenches— Disables bench auto discovery.
- Target tables: (see configuration for settings)
[lib]— Library target settings.[[bin]]— Binary target settings.[[example]]— Example target settings.[[test]]— Test target settings.[[bench]]— Benchmark target settings.
- Dependency tables:
[dependencies]— Package library dependencies.[dev-dependencies]— Dependencies for examples, tests, and benchmarks.[build-dependencies]— Dependencies for build scripts.[target]— Platform-specific dependencies.
[badges]— Badges to display on a registry.[features]— Conditional compilation features.[patch]— Override dependencies.[replace]— Override dependencies (deprecated).[profile]— Compiler settings and optimizations.[workspace]— The workspace definition.
The [package] section
The first section in a Cargo.toml is [package].
[package]
name = "hello_world" # the name of the package
version = "0.1.0" # the current version, obeying semver
authors = ["Alice <a@example.com>", "Bob <b@example.com>"]
The only fields required by Cargo are name and
version. If publishing to a registry, the registry may
require additional fields. See the notes below and the publishing
chapter for requirements for publishing to crates.io.
The name field
The package name is an identifier used to refer to the package. It is used when listed as a dependency in another package, and as the default name of inferred lib and bin targets.
The name must use only alphanumeric characters or - or _, and cannot be empty.
Note that cargo new and cargo init impose some additional restrictions on
the package name, such as enforcing that it is a valid Rust identifier and not
a keyword. crates.io imposes even more restrictions, such as
enforcing only ASCII characters, not a reserved name, not a special Windows
name such as "nul", is not too long, etc.
The version field
Cargo bakes in the concept of Semantic Versioning, so make sure you follow some basic rules:
- Before you reach 1.0.0, anything goes, but if you make breaking changes, increment the minor version. In Rust, breaking changes include adding fields to structs or variants to enums.
- After 1.0.0, only make breaking changes when you increment the major version. Don’t break the build.
- After 1.0.0, don’t add any new public API (no new
pubanything) in patch-level versions. Always increment the minor version if you add any newpubstructs, traits, fields, types, functions, methods or anything else. - Use version numbers with three numeric parts such as 1.0.0 rather than 1.0.
See the Resolver chapter for more information on how Cargo uses versions to resolve dependencies, and for guidelines on setting your own version. See the Semver compatibility chapter for more details on exactly what constitutes a breaking change.
The authors field
The authors field lists people or organizations that are considered the
"authors" of the package. The exact meaning is open to interpretation — it may
list the original or primary authors, current maintainers, or owners of the
package. These names will be listed on the crate's page on
crates.io. An optional email address may be included within angled
brackets at the end of each author.
Note: crates.io requires at least one author to be listed.
The edition field
You can opt in to a specific Rust Edition for your package with the
edition key in Cargo.toml. If you don't specify the edition, it will
default to 2015.
[package]
# ...
edition = '2018'
The edition key affects which edition your package is compiled with. Cargo
will always generate packages via cargo new with the edition key set to the
latest edition. Setting the edition key in [package] will affect all
targets/crates in the package, including test suites, benchmarks, binaries,
examples, etc.
The description field
The description is a short blurb about the package. crates.io will display this with your package. This should be plain text (not Markdown).
[package]
# ...
description = "A short description of my package"
Note: crates.io requires the
descriptionto be set.
The documentation field
The documentation field specifies a URL to a website hosting the crate's
documentation. If no URL is specified in the manifest file, crates.io will
automatically link your crate to the corresponding docs.rs page.
[package]
# ...
documentation = "https://docs.rs/bitflags"
The readme field
The readme field should be the path to a file in the package root (relative
to this Cargo.toml) that contains general information about the package.
This file will be transferred to the registry when you publish. crates.io
will interpret it as Markdown and render it on the crate's page.
[package]
# ...
readme = "README.md"
If no value is specified for this field, and a file named README.md,
README.txt or README exists in the package root, then the name of that
file will be used. You can suppress this behavior by setting this field to
false. If the field is set to true, a default value of README.md will
be assumed.
The homepage field
The homepage field should be a URL to a site that is the home page for your
package.
[package]
# ...
homepage = "https://serde.rs/"
The repository field
The repository field should be a URL to the source repository for your
package.
[package]
# ...
repository = "https://github.com/rust-lang/cargo/"
The license and license-file fields
The license field contains the name of the software license that the package
is released under. The license-file field contains the path to a file
containing the text of the license (relative to this Cargo.toml).
crates.io interprets the license field as an SPDX 2.1 license
expression. The name must be a known license
from the SPDX license list 3.6. Parentheses are not
currently supported. See the SPDX site for more information.
SPDX license expressions support AND and OR operators to combine multiple licenses.1
[package]
# ...
license = "MIT OR Apache-2.0"
Using OR indicates the user may choose either license. Using AND indicates
the user must comply with both licenses simultaneously. The WITH operator
indicates a license with a special exception. Some examples:
MIT OR Apache-2.0LGPL-2.1-only AND MIT AND BSD-2-ClauseGPL-2.0-or-later WITH Bison-exception-2.2
If a package is using a nonstandard license, then the license-file field may
be specified in lieu of the license field.
[package]
# ...
license-file = "LICENSE.txt"
Note: crates.io requires either
licenseorlicense-fileto be set.
Previously multiple licenses could be separated with a /, but that
usage is deprecated.
The keywords field
The keywords field is an array of strings that describe this package. This
can help when searching for the package on a registry, and you may choose any
words that would help someone find this crate.
[package]
# ...
keywords = ["gamedev", "graphics"]
Note: crates.io has a maximum of 5 keywords. Each keyword must be ASCII text, start with a letter, and only contain letters, numbers,
_or-, and have at most 20 characters.
The categories field
The categories field is an array of strings of the categories this package
belongs to.
categories = ["command-line-utilities", "development-tools::cargo-plugins"]
Note: crates.io has a maximum of 5 categories. Each category should match one of the strings available at https://crates.io/category_slugs, and must match exactly.
The workspace field
The workspace field can be used to configure the workspace that this package
will be a member of. If not specified this will be inferred as the first
Cargo.toml with [workspace] upwards in the filesystem. Setting this is
useful if the member is not inside a subdirectory of the workspace root.
[package]
# ...
workspace = "path/to/workspace/root"
This field cannot be specified if the manifest already has a [workspace]
table defined. That is, a crate cannot both be a root crate in a workspace
(contain [workspace]) and also be a member crate of another workspace
(contain package.workspace).
For more information, see the workspaces chapter.
The build field
The build field specifies a file in the package root which is a build
script for building native code. More information can be found in the build
script guide.
[package]
# ...
build = "build.rs"
The default is "build.rs", which loads the script from a file named
build.rs in the root of the package. Use build = "custom_build_name.rs" to
specify a path to a different file or build = false to disable automatic
detection of the build script.
The links field
The links field specifies the name of a native library that is being linked
to. More information can be found in the links section of the build
script guide.
[package]
# ...
links = "foo"
The exclude and include fields
You can explicitly specify that a set of file patterns should be ignored or
included for the purposes of packaging. The patterns specified in the
exclude field identify a set of files that are not included, and the
patterns in include specify files that are explicitly included.
The patterns should be gitignore-style patterns. Briefly:
foomatches any file or directory with the namefooanywhere in the package. This is equivalent to the pattern**/foo./foomatches any file or directory with the namefooonly in the root of the package.foo/matches any directory with the namefooanywhere in the package.- Common glob patterns like
*,?, and[]are supported:*matches zero or more characters except/. For example,*.htmlmatches any file or directory with the.htmlextension anywhere in the package.?matches any character except/. For example,foo?matchesfood, but notfoo.[]allows for matching a range of characters. For example,[ab]matches eitheraorb.[a-z]matches letters a through z.
**/prefix matches in any directory. For example,**/foo/barmatches the file or directorybaranywhere that is directly under directoryfoo./**suffix matches everything inside. For example,foo/**matches all files inside directoryfoo, including all files in subdirectories belowfoo./**/matches zero or more directories. For example,a/**/bmatchesa/b,a/x/b,a/x/y/b, and so on.!prefix negates a pattern. For example, a pattern ofsrc/**.rsand!foo.rswould match all files with the.rsextension inside thesrcdirectory, except for any file namedfoo.rs.
If git is being used for a package, the exclude field will be seeded with
the gitignore settings from the repository.
[package]
# ...
exclude = ["build/**/*.o", "doc/**/*.html"]
[package]
# ...
include = ["src/**/*", "Cargo.toml"]
The options are mutually exclusive: setting include will override an
exclude. Note that include must be an exhaustive list of files as otherwise
necessary source files may not be included. The package's Cargo.toml is
automatically included.
The include/exclude list is also used for change tracking in some situations.
For targets built with rustdoc, it is used to determine the list of files to
track to determine if the target should be rebuilt. If the package has a
build script that does not emit any rerun-if-* directives, then the
include/exclude list is used for tracking if the build script should be re-run
if any of those files change.
The publish field
The publish field can be used to prevent a package from being published to a
package registry (like crates.io) by mistake, for instance to keep a package
private in a company.
[package]
# ...
publish = false
The value may also be an array of strings which are registry names that are allowed to be published to.
[package]
# ...
publish = ["some-registry-name"]
If publish array contains a single registry, cargo publish command will use
it when --registry flag is not specified.
The metadata table
Cargo by default will warn about unused keys in Cargo.toml to assist in
detecting typos and such. The package.metadata table, however, is completely
ignored by Cargo and will not be warned about. This section can be used for
tools which would like to store package configuration in Cargo.toml. For
example:
[package]
name = "..."
# ...
# Metadata used when generating an Android APK, for example.
[package.metadata.android]
package-name = "my-awesome-android-app"
assets = "path/to/static"
There is a similar table at the workspace level at
workspace.metadata. While cargo does not specify a
format for the content of either of these tables, it is suggested that
external tools may wish to use them in a consistent fashion, such as referring
to the data in workspace.metadata if data is missing from package.metadata,
if that makes sense for the tool in question.
The default-run field
The default-run field in the [package] section of the manifest can be used
to specify a default binary picked by cargo run. For example, when there is
both src/bin/a.rs and src/bin/b.rs:
[package]
default-run = "a"
The [badges] section
The [badges] section is for specifying status badges that can be displayed
on a registry website when the package is published.
Note: crates.io previously displayed badges next to a crate on its website, but that functionality has been removed. Packages should place badges in its README file which will be displayed on crates.io (see the
readmefield).
[badges]
# The `maintenance` table indicates the status of the maintenance of
# the crate. This may be used by a registry, but is currently not
# used by crates.io. See https://github.com/rust-lang/crates.io/issues/2437
# and https://github.com/rust-lang/crates.io/issues/2438 for more details.
#
# The `status` field is required. Available options are:
# - `actively-developed`: New features are being added and bugs are being fixed.
# - `passively-maintained`: There are no plans for new features, but the maintainer intends to
# respond to issues that get filed.
# - `as-is`: The crate is feature complete, the maintainer does not intend to continue working on
# it or providing support, but it works for the purposes it was designed for.
# - `experimental`: The author wants to share it with the community but is not intending to meet
# anyone's particular use case.
# - `looking-for-maintainer`: The current maintainer would like to transfer the crate to someone
# else.
# - `deprecated`: The maintainer does not recommend using this crate (the description of the crate
# can describe why, there could be a better solution available or there could be problems with
# the crate that the author does not want to fix).
# - `none`: Displays no badge on crates.io, since the maintainer has not chosen to specify
# their intentions, potential crate users will need to investigate on their own.
maintenance = { status = "..." }
Dependency sections
See the specifying dependencies page for
information on the [dependencies], [dev-dependencies],
[build-dependencies], and target-specific [target.*.dependencies] sections.
The [profile.*] sections
The [profile] tables provide a way to customize compiler settings such as
optimizations and debug settings. See the Profiles chapter for
more detail.