[FR]: Add support for runtime_toolchain_type for jq/yq/...

[BoleynSu]

What is the current behavior?

No response

Describe the feature

The current toolchain only provides the binary for use during the build but no binary for the build output. People already misuse the cfg=exec binary in a cfg=target output, e.g. https://github.com/bazel-contrib/rules_oci/blob/main/oci/private/push.sh.tpl. Providing another runtime_toolchain_type (similar to what rules_java does) can help improve the current situation. Alternatively, we can provide both exec and target binary in the current toolchain and ask users to use the correct binary.

[alexeagle]

We didn't intend to provide jq or yq for the target platform, and from this issue I don't understand why that would be useful. the rules_oci push.sh you point to is meant to be run on the host machine with bazel run so it shouldn't need cfg=target tools.

[BoleynSu]

jq/yq is used at runtime (target) while the binary is for build time (exec). For example, you can think bout how java works if you compile on Linux for Linux with Windows executors. When we run the build results, it should not use java.exe.

[anguslees]

from this issue I don't understand why that would be useful

Eg: using jq/yq in executable rules (ie: bazel tests or bazel run scripts)

[BoleynSu]

#875 partially implements this feature.