Config

Contains all of the configuration options used when running generate

The accepted field

Priority list of all the accepted licenses for a project. cargo-about will try to satisfy the licenses in the order that they are declared in this list. So in the below example, if a crate is licensed with the typical Apache-2.0 OR MIT license expression, only the Apache-2.0 license would be used as it has higher priority than MIT only one of them is required. This list applies globally to all crates. The licenses specified here are used to satisfy the license expressions for every crate, if they can't be satisfied then cargo-about will emit an error for why.

accepted = [
    "Apache-2.0",
    "MIT",
]

The targets field (optional)

A list of targets that are actually building for. Crates which are only included via cfg() expressions that don't match one or more of the listed targets will be ignored. Note that currently the targets are evaluated all at once, so there might be cases where a crate is included that is actually impossible for any one target alone.

targets = [
    "x86_64-unknown-linux-gnu",
    "x86_64-unknown-linux-musl",
    "x86_64-pc-windows-msvc",
    "x86_64-apple-darwin",
]

The ignore-build-dependencies field (optional)

If true, all crates that are only used as build dependencies will be ignored.

ignore-build-dependencies = true

The ignore-dev-dependencies field (optional)

If true, all crates that are only used as dev dependencies will be ignored.

ignore-dev-dependencies = true

The ignore-transitive-dependencies field (optional)

If true, only direct dependencies of crates in the workspace will be included in the graph, transitive dependencies (dependencies of dependencies) will be ignored.

ignore-transitive-dependencies = true

The no-clearly-defined field (optional)

If true, will not attempt to lookup licensing information for any crate from https://clearlydefined.io, only user clarifications, workarounds, and local file scanning will be used to determine licensing information.

The workarounds field (optional)

Unfortunately, not all crates properly package their licenses, or if they do, sometimes in a non-machine readable format, or in a few cases, are slightly wrong. These can be clarified manually via configuration, but some crates that are widely used in the Rust ecosystem have these issues, and rather than require that every cargo-about user who happens to have a dependency on one or more of these crates specify the same config to get it working, cargo-about instead includes a few built-in clarifications that can be opted into with a single config entry rather than redoing work.

See Workarounds for a list of the workarounds currently built-in to cargo-about

workarounds = [
    "ring",
    "rustls",
]

The private field (optional)

It's often not useful or wanted to check for licenses in your own private workspace crates. So the private field allows you to do so.

The ignore field

If true, workspace members will not have their license expression checked, if they are not published.

# Cargo.toml
[package]
name = "sekret"
license = "¯\_(ツ)_/¯"
publish = false # "private"!
# about.toml

# The sekret package would be ignored now
private = { ignore = true }

The registries field

A list of private registries you may publish your workspace crates to. If a workspace member only publishes to private registries, it will also be ignored if private.ignore = true

# Cargo.toml
[package]
name = "sekret"
license = "¯\_(ツ)_/¯"
publish = ["sauce"]
# about.toml

# Still ignored!
private = { ignore = true, registries = ["sauce"] }

Crate configuration

Along with the global options, crates can be individually configured as well, using the name of the crate as the key. Crate specific configuration must come last in the config file.

The accepted field (optional)

Just as with the global accepted field, this accepts specific licenses for the crate. These licenses are appended to the global list, and are again in priority order. So for example, if the global accept was like this:

accepted = ["MIT", "ISC"]

And we are using ring, which also is licensed under the OpenSSL license, we could use the following configuration to satisfy the license requirements of ring.

accepted = ["MIT", "ISC"]

[ring]
accepted = ["OpenSSL"]

The clarify field (optional)

As noted in the workarounds, some crates have complicated or incomplete licensing that messes up the harvesting of the license info in an automated fashion. While the workarounds exists for popular crates (and can always be expanded with PRs!) there are often going to be crates that you will need to clarify yourself until a new release of the crate, etc, which is the purpose of the clarify field, to specify exactly what the license information is, and how to verify that the license terms are still the same as when they were clarified, using hashes of the input files.

Note that since clarifications are human supplied in your project's own configuration, they take precedence over all other methods. If a crate is clarified, it will not be retrieved from clearlydefined.io nor via local file harvesting.

The license field

This is the top level SPDX expression for the crate as a whole. It should be noted that this actually overrides the license expression of the crate itself if it exists, though in most cases this will be the same as the stated license, it is simply required so that you can't accidentally forget it in the cases where it does differ.

[ring.clarify]
license = "ISC AND MIT AND OpenSSL"

The override-git-commit field (optional)

When clarifying a crate with files pulled from its source git repository, cargo-about will normally read the contents of the .cargo_vcs_info.json file that is usually part of a published crate's contents, which includes the full commit hash at the time the crate was published. However, this file is not guaranteed to be present (eg, if the crate is published with cargo publish --allow-dirty), so in that case the git ref to pull the license file contents must be supplied. This can either be a full git revision, or a git tag.

[core-graphics-types.clarify]
override-git-commit = "3841d2bb3aa76dec2ea6319e757603fb923b5a50"

The files and/or git field

When clarifying the license of a crate, it is required to give a source of truth for the licenses in the expression, to prevent drift between the clarification and the actual licensing of the crate in question. For example, if a crate uses the Zlib license, then changes between releases to use the MIT license instead, the source of truth (eg. the LICENSE file) would also (hopefully...) change resulting in a hash mismatch that means the clarification would not be used.

We'll be using this example for the ring crate

[ring.clarify]
license = "ISC AND MIT AND OpenSSL"

[[ring.clarify.files]]
path = 'LICENSE'
license = 'OpenSSL'
checksum = '53552a9b197cd0db29bd085d81253e67097eedd713706e8cd2a3cc6c29850ceb'
start = '/* ===================================================================='
end = '\n * Hudson (tjh@cryptsoft.com).\n *\n */'
The path field

This is the relative path to the file from the root. For files this is the root of the crate, but for git this is the repo root.

The license field (optional)

In a multiple license situation it can be useful to supply the exact license for the file. If this is not supplied the parent clarify.license expression is used instead.

The checksum field

This is the full sha-256 checksum of the contents. If this doesn't match the computed checksum, the clarification will not be used.

The start field (optional)

In some cases, crates concatenate multiple licenses together into a single file, which confuses machine readers, and makes splatting the license text into the final generated template a pain, so in those cases you need to supply a place in the text that a license starts and/or ends from. This is just a simple substring find.

The end field (optional)

Just as with start, this is just a simple substring find, however, it will only match text that comes after the position the start text (or beginning of the file) was found.