Allow Cargo.toml as configuration source

CHANGELOG.md

@@ -17,6 +17,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - #678 - Add `target.{target}.pre-build` config for running commands before building the image.
 - #772 - added `CROSS_CONTAINER_OPTS` environment variable to replace `DOCKER_OPTS`.
 - #767, #788 - added the `cross-util` and `xtask` commands.
+- #842 - Add `Cargo.toml` as configuration source
 - #745 - added `thumbv7neon-*` targets.
 - #741 - added `armv7-unknown-linux-gnueabi` and `armv7-unknown-linux-musleabi` targets.
 - #721 - add support for running doctests on nightly if `CROSS_UNSTABLE_ENABLE_DOCTESTS=true`.

README.md

@@ -84,9 +84,27 @@ Additional documentation can be found on the [wiki](https://github.com/cross-rs/
 
 ## Configuration
 
-You can place a `Cross.toml` file in the root of your Cargo project or use a
-`CROSS_CONFIG` environment variable to tweak `cross`'s behavior. The format
-of `Cross.toml` is documented in [docs/cross_toml.md](docs/cross_toml.md).
+You have three options to configure `cross`. All of these options use the TOML format for configuration and the possible configuration values are documented [here](docs/cross_toml.md).
+
+### Option 1: Configuring `cross` directly in your `Cargo.toml`
+
+You can directly set [configuration values](docs/cross_toml.md) in your `Cargo.toml` file, under the `[package.metadata.cross]` table, i.e. key prefix.
+An example config snippet would look like this:
+
+```
+[package.metadata.cross.target.aarch64-unknown-linux-gnu]
+xargo = false
+image = "test-image"
+runner = "custom-runner"
+```
+
+### Option 2: Configuring `cross` via a `Cross.toml` file
+
+You can put your [configuration](docs/cross_toml.md) inside a `Cross.toml` file in your project root directory.
+
+### Option 3: Using `CROSS_CONFIG` to specify the location of your configuration
+
+By setting the `CROSS_CONFIG` environment variable, you can tell `cross` where it should search for the config file. This way you are not limited to a `Cross.toml` file in the project root.
 
 ### Custom Docker images
 

docs/cross_toml.md

@@ -1,4 +1,6 @@
-The `cross` configuration in the `Cross.toml` file, can contain the following elements:
+The `cross` configuration in the `Cross.toml` file, can contain the elements described below.
+
+If the configuration is given in the `Cargo.toml`, these table headers must be of the form `[package.metadata.cross.<KEY>]`.
 
 # `build`
 

src/config.rs

@@ -431,7 +431,9 @@ mod tests {
         use std::matches;
 
         fn toml(content: &str) -> Result<crate::CrossToml> {
-            Ok(CrossToml::parse(content).wrap_err("couldn't parse toml")?.0)
+            Ok(CrossToml::parse_from_cross(content)
+                .wrap_err("couldn't parse toml")?
+                .0)
         }
 
         #[test]