Workspaces
A workspace is a collection of one or more packages, called workspace members, that are managed together.
The key points of workspaces are:
- Common commands can run across all workspace members, like
cargo check --workspace
. - All packages share a common
Cargo.lock
file which resides in the workspace root. - All packages share a common output directory, which defaults to a
directory named
target
in the workspace root. - Sharing package metadata, like with
workspace.package
. - The
[patch]
,[replace]
and[profile.*]
sections inCargo.toml
are only recognized in the root manifest, and ignored in member crates’ manifests.
In the Cargo.toml
, the [workspace]
table supports the following sections:
[workspace]
— Defines a workspace.resolver
— Sets the dependency resolver to use.members
— Packages to include in the workspace.exclude
— Packages to exclude from the workspace.default-members
— Packages to operate on when a specific package wasn’t selected.package
— Keys for inheriting in packages.dependencies
— Keys for inheriting in package dependencies.lints
— Keys for inheriting in package lints.metadata
— Extra settings for external tools.
[patch]
— Override dependencies.[replace]
— Override dependencies (deprecated).[profile]
— Compiler settings and optimizations.
The [workspace]
section
To create a workspace, you add the [workspace]
table to a Cargo.toml
:
[workspace]
# ...
At minimum, a workspace has to have a member, either with a root package or as a virtual manifest.
Root package
If the [workspace]
section is added to a
Cargo.toml
that already defines a [package]
, the package is
the root package of the workspace. The workspace root is the directory
where the workspace’s Cargo.toml
is located.
[workspace]
[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>"]
Virtual workspace
Alternatively, a Cargo.toml
file can be created with a [workspace]
section
but without a [package]
section. This is called a virtual
manifest. This is typically useful when there isn’t a “primary” package, or
you want to keep all the packages organized in separate directories.
# [PROJECT_DIR]/Cargo.toml
[workspace]
members = ["hello_world"]
resolver = "2"
# [PROJECT_DIR]/hello_world/Cargo.toml
[package]
name = "hello_world" # the name of the package
version = "0.1.0" # the current version, obeying semver
edition = "2021" # the edition, will have no effect on a resolver used in the workspace
authors = ["Alice <a@example.com>", "Bob <b@example.com>"]
Note that in a virtual manifest the resolver = "2"
should be specified manually. It is usually deduced from the package.edition
field which is absent in virtual manifests and the edition field of a member
won’t affect the resolver used by the workspace.
The members
and exclude
fields
The members
and exclude
fields define which packages are members of
the workspace:
[workspace]
members = ["member1", "path/to/member2", "crates/*"]
exclude = ["crates/foo", "path/to/other"]
All path
dependencies residing in the workspace directory automatically
become members. Additional members can be listed with the members
key, which
should be an array of strings containing directories with Cargo.toml
files.
The members
list also supports globs to match multiple paths, using
typical filename glob patterns like *
and ?
.
The exclude
key can be used to prevent paths from being included in a
workspace. This can be useful if some path dependencies aren’t desired to be
in the workspace at all, or using a glob pattern and you want to remove a
directory.
When inside a subdirectory within the workspace, Cargo will automatically
search the parent directories for a Cargo.toml
file with a [workspace]
definition to determine which workspace to use. The package.workspace
manifest key can be used in member crates to point at a workspace’s root to
override this automatic search. The manual setting can be useful if the member
is not inside a subdirectory of the workspace root.
Package selection
In a workspace, package-related Cargo commands like cargo build
can use
the -p
/ --package
or --workspace
command-line flags to determine which
packages to operate on. If neither of those flags are specified, Cargo will
use the package in the current working directory. If the current directory is
a virtual workspace, it will apply to all members (as if
--workspace
were specified on the command-line). See also
default-members
.
The default-members
field
The optional default-members
key can be specified to set the members to
operate on when in the workspace root and the package selection flags are not
used:
[workspace]
members = ["path/to/member1", "path/to/member2", "path/to/member3/*"]
default-members = ["path/to/member2", "path/to/member3/foo"]
When specified, default-members
must expand to a subset of members
.
The package
table
The workspace.package
table is where you define keys that can be
inherited by members of a workspace. These keys can be inherited by
defining them in the member package with {key}.workspace = true
.
Keys that are supported:
authors | categories |
description | documentation |
edition | exclude |
homepage | include |
keywords | license |
license-file | publish |
readme | repository |
rust-version | version |
license-file
andreadme
are relative to the workspace rootinclude
andexclude
are relative to your package root
Example:
# [PROJECT_DIR]/Cargo.toml
[workspace]
members = ["bar"]
[workspace.package]
version = "1.2.3"
authors = ["Nice Folks"]
description = "A short description of my package"
documentation = "https://example.com/bar"
# [PROJECT_DIR]/bar/Cargo.toml
[package]
name = "bar"
version.workspace = true
authors.workspace = true
description.workspace = true
documentation.workspace = true
The dependencies
table
The workspace.dependencies
table is where you define dependencies to be
inherited by members of a workspace.
Specifying a workspace dependency is similar to package dependencies except:
- Dependencies from this table cannot be declared as
optional
features
declared in this table are additive with thefeatures
from[dependencies]
You can then inherit the workspace dependency as a package dependency
Example:
# [PROJECT_DIR]/Cargo.toml
[workspace]
members = ["bar"]
[workspace.dependencies]
cc = "1.0.73"
rand = "0.8.5"
regex = { version = "1.6.0", default-features = false, features = ["std"] }
# [PROJECT_DIR]/bar/Cargo.toml
[package]
name = "bar"
version = "0.2.0"
[dependencies]
regex = { workspace = true, features = ["unicode"] }
[build-dependencies]
cc.workspace = true
[dev-dependencies]
rand.workspace = true
The lints
table
The workspace.lints
table is where you define lint configuration to be inherited by members of a workspace.
Specifying a workspace lint configuration is similar to package lints.
Example:
# [PROJECT_DIR]/Cargo.toml
[workspace]
members = ["crates/*"]
[workspace.lints.rust]
unsafe_code = "forbid"
# [PROJECT_DIR]/crates/bar/Cargo.toml
[package]
name = "bar"
version = "0.1.0"
[lints]
workspace = true
The metadata
table
The workspace.metadata
table is ignored by Cargo and will not be warned
about. This section can be used for tools that would like to store workspace
configuration in Cargo.toml
. For example:
[workspace]
members = ["member1", "member2"]
[workspace.metadata.webcontents]
root = "path/to/webproject"
tool = ["npm", "run", "build"]
# ...
There is a similar set of tables at the package level at
package.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.