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cargo-metadata - Man Page

Machine-readable metadata about the current package

Examples (TL;DR)

Synopsis

cargo metadata [options]

Description

Output JSON to stdout containing information about the workspace members and resolved dependencies of the current package.

The format of the output is subject to change in futures versions of Cargo. It is recommended to include the --format-version flag to future-proof your code to ensure the output is in the format you are expecting. For more on the expectations, see “Compatibility”.

See the cargo_metadata crate <https://crates.io/crates/cargo_metadata> for a Rust API for reading the metadata.

Output Format

Compatibility

Within the same output format version, the compatibility is maintained, except some scenarios. The following is a non-exhaustive list of changes that are not considersed as incompatible:

  • Adding new fields — New fields will be added when needed. Reserving this helps Cargo evolve without bumping the format version too often.
  • Adding new values for enum-like fields — Same as adding new fields. It keeps metadata evolving without stagnation.
  • Changing opaque representations — The inner representations of some fields are implementation details. For example, fields related to “Source ID” are treated as opaque identifiers to differentiate packages or sources. Consumers shouldn’t rely on those representations unless specified.

JSON format

The JSON output has the following format:

{
    /* Array of all packages in the workspace.
       It also includes all feature-enabled dependencies unless --no-deps is used.
    */
    "packages": [
        {
            /* The name of the package. */
            "name": "my-package",
            /* The version of the package. */
            "version": "0.1.0",
            /* The Package ID for referring to the
               package within the document and as the `--package` argument to many commands
            */
            "id": "file:///path/to/my-package#0.1.0",
            /* The license value from the manifest, or null. */
            "license": "MIT/Apache-2.0",
            /* The license-file value from the manifest, or null. */
            "license_file": "LICENSE",
            /* The description value from the manifest, or null. */
            "description": "Package description.",
            /* The source ID of the package, an "opaque" identifier representing
               where a package is retrieved from. See "Compatibility" above for
               the stability guarantee.

               This is null for path dependencies and workspace members.

               For other dependencies, it is a string with the format:
               - "registry+URL" for registry-based dependencies.
                 Example: "registry+https://github.com/rust-lang/crates.io-index"
               - "git+URL" for git-based dependencies.
                 Example: "git+https://github.com/rust-lang/cargo?rev=5e85ba14aaa20f8133863373404cb0af69eeef2c#5e85ba14aaa20f8133863373404cb0af69eeef2c"
               - "sparse+URL" for dependencies from a sparse registry
                 Example: "sparse+https://my-sparse-registry.org"

               The value after the `+` is not explicitly defined, and may change
               between versions of Cargo and may not directly correlate to other
               things, such as registry definitions in a config file. New source
               kinds may be added in the future which will have different `+`
               prefixed identifiers.
            */
            "source": null,
            /* Array of dependencies declared in the package's manifest. */
            "dependencies": [
                {
                    /* The name of the dependency. */
                    "name": "bitflags",
                    /* The source ID of the dependency. May be null, see
                       description for the package source.
                    */
                    "source": "registry+https://github.com/rust-lang/crates.io-index",
                    /* The version requirement for the dependency.
                       Dependencies without a version requirement have a value of "*".
                    */
                    "req": "^1.0",
                    /* The dependency kind.
                       "dev", "build", or null for a normal dependency.
                    */
                    "kind": null,
                    /* If the dependency is renamed, this is the new name for
                       the dependency as a string.  null if it is not renamed.
                    */
                    "rename": null,
                    /* Boolean of whether or not this is an optional dependency. */
                    "optional": false,
                    /* Boolean of whether or not default features are enabled. */
                    "uses_default_features": true,
                    /* Array of features enabled. */
                    "features": [],
                    /* The target platform for the dependency.
                       null if not a target dependency.
                    */
                    "target": "cfg(windows)",
                    /* The file system path for a local path dependency.
                       not present if not a path dependency.
                    */
                    "path": "/path/to/dep",
                    /* A string of the URL of the registry this dependency is from.
                       If not specified or null, the dependency is from the default
                       registry (crates.io).
                    */
                    "registry": null
                }
            ],
            /* Array of Cargo targets. */
            "targets": [
                {
                    /* Array of target kinds.
                       - lib targets list the `crate-type` values from the
                         manifest such as "lib", "rlib", "dylib",
                         "proc-macro", etc. (default ["lib"])
                       - binary is ["bin"]
                       - example is ["example"]
                       - integration test is ["test"]
                       - benchmark is ["bench"]
                       - build script is ["custom-build"]
                    */
                    "kind": [
                        "bin"
                    ],
                    /* Array of crate types.
                       - lib and example libraries list the `crate-type` values
                         from the manifest such as "lib", "rlib", "dylib",
                         "proc-macro", etc. (default ["lib"])
                       - all other target kinds are ["bin"]
                    */
                    "crate_types": [
                        "bin"
                    ],
                    /* The name of the target. */
                    "name": "my-package",
                    /* Absolute path to the root source file of the target. */
                    "src_path": "/path/to/my-package/src/main.rs",
                    /* The Rust edition of the target.
                       Defaults to the package edition.
                    */
                    "edition": "2018",
                    /* Array of required features.
                       This property is not included if no required features are set.
                    */
                    "required-features": ["feat1"],
                    /* Whether the target should be documented by `cargo doc`. */
                    "doc": true,
                    /* Whether or not this target has doc tests enabled, and
                       the target is compatible with doc testing.
                    */
                    "doctest": false,
                    /* Whether or not this target should be built and run with `--test`
                    */
                    "test": true
                }
            ],
            /* Set of features defined for the package.
               Each feature maps to an array of features or dependencies it
               enables.
            */
            "features": {
                "default": [
                    "feat1"
                ],
                "feat1": [],
                "feat2": []
            },
            /* Absolute path to this package's manifest. */
            "manifest_path": "/path/to/my-package/Cargo.toml",
            /* Package metadata.
               This is null if no metadata is specified.
            */
            "metadata": {
                "docs": {
                    "rs": {
                        "all-features": true
                    }
                }
            },
            /* List of registries to which this package may be published.
               Publishing is unrestricted if null, and forbidden if an empty array. */
            "publish": [
                "crates-io"
            ],
            /* Array of authors from the manifest.
               Empty array if no authors specified.
            */
            "authors": [
                "Jane Doe <user@example.com>"
            ],
            /* Array of categories from the manifest. */
            "categories": [
                "command-line-utilities"
            ],
            /* Optional string that is the default binary picked by cargo run. */
            "default_run": null,
            /* Optional string that is the minimum supported rust version */
            "rust_version": "1.56",
            /* Array of keywords from the manifest. */
            "keywords": [
                "cli"
            ],
            /* The readme value from the manifest or null if not specified. */
            "readme": "README.md",
            /* The repository value from the manifest or null if not specified. */
            "repository": "https://github.com/rust-lang/cargo",
            /* The homepage value from the manifest or null if not specified. */
            "homepage": "https://rust-lang.org",
            /* The documentation value from the manifest or null if not specified. */
            "documentation": "https://doc.rust-lang.org/stable/std",
            /* The default edition of the package.
               Note that individual targets may have different editions.
            */
            "edition": "2018",
            /* Optional string that is the name of a native library the package
               is linking to.
            */
            "links": null,
        }
    ],
    /* Array of members of the workspace.
       Each entry is the Package ID for the package.
    */
    "workspace_members": [
        "file:///path/to/my-package#0.1.0",
    ],
    /* Array of default members of the workspace.
       Each entry is the Package ID for the package.
    */
    "workspace_default_members": [
        "file:///path/to/my-package#0.1.0",
    ],
    // The resolved dependency graph for the entire workspace. The enabled
    // features are based on the enabled features for the "current" package.
    // Inactivated optional dependencies are not listed.
    //
    // This is null if --no-deps is specified.
    //
    // By default, this includes all dependencies for all target platforms.
    // The `--filter-platform` flag may be used to narrow to a specific
    // target triple.
    "resolve": {
        /* Array of nodes within the dependency graph.
           Each node is a package.
        */
        "nodes": [
            {
                /* The Package ID of this node. */
                "id": "file:///path/to/my-package#0.1.0",
                /* The dependencies of this package, an array of Package IDs. */
                "dependencies": [
                    "https://github.com/rust-lang/crates.io-index#bitflags@1.0.4"
                ],
                /* The dependencies of this package. This is an alternative to
                   "dependencies" which contains additional information. In
                   particular, this handles renamed dependencies.
                */
                "deps": [
                    {
                        /* The name of the dependency's library target.
                           If this is a renamed dependency, this is the new
                           name.
                        */
                        "name": "bitflags",
                        /* The Package ID of the dependency. */
                        "pkg": "https://github.com/rust-lang/crates.io-index#bitflags@1.0.4"
                        /* Array of dependency kinds. Added in Cargo 1.40. */
                        "dep_kinds": [
                            {
                                /* The dependency kind.
                                   "dev", "build", or null for a normal dependency.
                                */
                                "kind": null,
                                /* The target platform for the dependency.
                                   null if not a target dependency.
                                */
                                "target": "cfg(windows)"
                            }
                        ]
                    }
                ],
                /* Array of features enabled on this package. */
                "features": [
                    "default"
                ]
            }
        ],
        /* The root package of the workspace.
           This is null if this is a virtual workspace. Otherwise it is
           the Package ID of the root package.
        */
        "root": "file:///path/to/my-package#0.1.0",
    },
    /* The absolute path to the build directory where Cargo places its output. */
    "target_directory": "/path/to/my-package/target",
    /* The version of the schema for this metadata structure.
       This will be changed if incompatible changes are ever made.
    */
    "version": 1,
    /* The absolute path to the root of the workspace. */
    "workspace_root": "/path/to/my-package"
    /* Workspace metadata.
       This is null if no metadata is specified. */
    "metadata": {
        "docs": {
            "rs": {
                "all-features": true
            }
        }
    }
}

Notes:

Options

Output Options

--no-deps

Output information only about the workspace members and don’t fetch dependencies.

--format-version version

Specify the version of the output format to use. Currently 1 is the only possible value.

--filter-platform triple

This filters the resolve output to only include dependencies for the given target triple <https://doc.rust-lang.org/cargo/appendix/glossary.html#target>. Without this flag, the resolve includes all targets.

Note that the dependencies listed in the “packages” array still includes all dependencies. Each package definition is intended to be an unaltered reproduction of the information within Cargo.toml.

Feature Selection

The feature flags allow you to control which features are enabled. When no feature options are given, the default feature is activated for every selected package.

See the features documentation <https://doc.rust-lang.org/cargo/reference/features.html#command-line-feature-options> for more details.

-F features,  --features features

Space or comma separated list of features to activate. Features of workspace members may be enabled with package-name/feature-name syntax. This flag may be specified multiple times, which enables all specified features.

--all-features

Activate all available features of all selected packages.

--no-default-features

Do not activate the default feature of the selected packages.

Display Options

-v,  --verbose

Use verbose output. May be specified twice for “very verbose” output which includes extra output such as dependency warnings and build script output. May also be specified with the term.verbose config value <https://doc.rust-lang.org/cargo/reference/config.html>.

-q,  --quiet

Do not print cargo log messages. May also be specified with the term.quiet config value <https://doc.rust-lang.org/cargo/reference/config.html>.

--color when

Control when colored output is used. Valid values:

  • auto (default): Automatically detect if color support is available on the terminal.
  • always: Always display colors.
  • never: Never display colors.

May also be specified with the term.color config value <https://doc.rust-lang.org/cargo/reference/config.html>.

Manifest Options

--manifest-path path

Path to the Cargo.toml file. By default, Cargo searches for the Cargo.toml file in the current directory or any parent directory.

--locked

Asserts that the exact same dependencies and versions are used as when the existing Cargo.lock file was originally generated. Cargo will exit with an error when either of the following scenarios arises:

  • The lock file is missing.
  • Cargo attempted to change the lock file due to a different dependency resolution.

It may be used in environments where deterministic builds are desired, such as in CI pipelines.

--offline

Prevents Cargo from accessing the network for any reason. Without this flag, Cargo will stop with an error if it needs to access the network and the network is not available. With this flag, Cargo will attempt to proceed without the network if possible.

Beware that this may result in different dependency resolution than online mode. Cargo will restrict itself to crates that are downloaded locally, even if there might be a newer version as indicated in the local copy of the index. See the cargo-fetch(1) command to download dependencies before going offline.

May also be specified with the net.offline config value <https://doc.rust-lang.org/cargo/reference/config.html>.

--frozen

Equivalent to specifying both --locked and --offline.

Common Options

+toolchain

If Cargo has been installed with rustup, and the first argument to cargo begins with +, it will be interpreted as a rustup toolchain name (such as +stable or +nightly). See the rustup documentation <https://rust-lang.github.io/rustup/overrides.html> for more information about how toolchain overrides work.

--config KEY=VALUE or PATH

Overrides a Cargo configuration value. The argument should be in TOML syntax of KEY=VALUE, or provided as a path to an extra configuration file. This flag may be specified multiple times. See the command-line overrides section <https://doc.rust-lang.org/cargo/reference/config.html#command-line-overrides> for more information.

-C PATH

Changes the current working directory before executing any specified operations. This affects things like where cargo looks by default for the project manifest (Cargo.toml), as well as the directories searched for discovering .cargo/config.toml, for example. This option must appear before the command name, for example cargo -C path/to/my-project build.

This option is only available on the nightly channel <https://doc.rust-lang.org/book/appendix-07-nightly-rust.html> and requires the -Z unstable-options flag to enable (see #10098 <https://github.com/rust-lang/cargo/issues/10098>).

-h,  --help

Prints help information.

-Z flag

Unstable (nightly-only) flags to Cargo. Run cargo -Z help for details.

Environment

See the reference <https://doc.rust-lang.org/cargo/reference/environment-variables.html> for details on environment variables that Cargo reads.

Exit Status

Examples

 1. Output JSON about the current package:

cargo metadata --format-version=1

See Also

cargo(1), cargo-pkgid(1), Package ID Specifications <https://doc.rust-lang.org/cargo/reference/pkgid-spec.html>, JSON messages <https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages>

Referenced By

cargo(1), cargo-locate-project(1), cargo-pkgid(1), cargo-tree(1).