| toolchain | Comma-separated list of Rust toolchain specifications. Last version becomes the default. -- see https://rust-lang.github.io/rustup/concepts/toolchains.html#toolchain-specification | no | — |
| target | Target triple to install for this toolchain | no | — |
| components | Comma-separated list of components to be additionally installed | no | — |
| cache | Automatically configure Rust cache | no | true |
| cache-workspaces | Paths to multiple Cargo workspaces and their target directories, separated by newlines. | no | — |
| cache-directories | Additional non workspace directories to be cached, separated by newlines. | no | — |
| cache-on-failure | Cache even if the build fails. | no | true |
| cache-key | An additional cache key that is added alongside the automatic `job`-based cache key and can be used to further differentiate jobs. | no | — |
| cache-shared-key | A cache key that is used instead of the automatic `job`-based key, and is stable over multiple jobs. | no | — |
| cache-bin | Determines whether to cache ${CARGO_HOME}/bin. | no | true |
| cache-provider | Determines which provider to use for caching. Options are github, buildjet, or warpbuild. Defaults to github. | no | github |
| cache-all-crates | Determines which crates are cached. If `true` all crates will be cached, otherwise only dependent crates will be cached. | no | false |
| cache-workspace-crates | Determines which crates are cached. If `true` all crates will be cached, otherwise only dependent crates will be cached. | no | false |
| cache-save-if | Determines whether the cache should be saved. If `false`, the cache is only restored. | no | true |
| matcher | Enable the Rust problem matcher | no | true |
| rustflags | set RUSTFLAGS environment variable, set to empty string to avoid overwriting build.rustflags | no | -D warnings |
| override | Setup the last installed toolchain as the default via `rustup override` | no | true |
| rust-src-dir | Specify path from root directory to the Rust source directory. By default root directory will be used. | no | — |