Container Support

The standalone-sign option can be called within the script referenced by a signing service (the docs for users: https://docs.pulpproject.org/pulpcore/workflows/signed-metadata.html; the docs for plugin writers: https://docs.pulpproject.org/pulpcore/plugins/reference/metadata-signing.html).

Users will then write their own signing scripts, respecting our interface (where we define how should the signing script behave - what files should it generate and so on). The interface may be enforced by inheriting from the SigningService model and implementing custom validation/verification methods. We have already done this for AsciiArmoredDetachedSigningService (github).

In the pulp_container backend, we will call the sign method of a customized signing service that executes the signing script and then we will eventually proceed further with publishing the created signatures. For instance, this is how we are using the signing service in pulp_rpm: github. And this is a script that is used for metadata signing in pulp_rpm: docs