My employer uses a combination of Protocol Buffers (for the config schema definition) and Bazel/Starlark (for concrete instantiations). Configs are validated at

My employer uses a combination of Protocol Buffers (for the config schema definition) and Bazel/Starlark (for concrete instantiations). Configs are validated at build time and runtime using CEL (https://github.com/google/cel-spec https://github.com/google/cel-spec).