I'm thinking the best way to approach this for now is via a new "codegen" plugin. You can have

deploy_jar

generate

ResourceSourceField

so that when you depend on it, it's like depending on

resource

but where it gets generated by ~running

./pants package

first https://www.pantsbuild.org/docs/plugins-codegen To do this, you'll want to add a private

sources

field to

deploy_jar

like this: https://github.com/pantsbuild/pants/blob/fe112bf20e9e7cfe4a2c746316ebc2655c428697/src/python/pants/core/target_types.py#L142-L145. You're just doing this to hook into codegen. Use a "plugin field" to extend the existing

deploy_jar

target: https://www.pantsbuild.org/docs/target-api-extending-targets Then, in your codegen rule, you'll call

await Get(BuiltPackage, DeployJarFieldSet, field_set)

I think. This essentially calls

./pants package

. You can then return the resulting

BuiltPackage.digest

in the

GeneratedSources

for your codegen rule We're happy to help more if you have questions along the way 🙂 Feel free to ask questions here or in #plugins We may want to generalize that cross-language relationship in core Pants, but in the meantime