Implement modularity content dependency solving
Pulp lacks the ability to perform dependency solving at a module level and to copy dependent modules and their artifacts during copy operation.
Pulp (@2.18) ignores module dependencies when copying modules recursively.
Pulp doesn't distinguish between modular and non-modular artifacts when recursively copying modules to a repository. Pulp however always copies all module artifacts, including the artifacts rpm dependencies.
A potential problem and a rare case:
- a mixture of modular and non-modular packages with the same NEVRA are present in a repo
- unlucky coincidence with versions
- as a result - a "bad" repo (client will likely have a problem with a module which doesn't have all its modular rpms in a repo, since some of the copied rpms were non-modular ones).
It's important for modules to have all their artifacts present in a repo.
Regardless of the depsolving strategy for RPMs, all module artifacts and related modules should be copied to a target repo. E.g if the target repository already contains units newer than a module requires, the module-required units need to be copied in the older version, in addition to the already present units.
Modules may depend on other modules, either for the build- or the run-time. Pulp should perform dependency solving based on runtime dependencies only. They are already available on the Modulemd model.
To support these usecases, a fake
libsolv solvable can be created for each module unit. This will allow tracking dependencies between the modules. To prevent non-modular content from satisfying dependencies in target repository, it seems exposing the
pool->considered bitmap from the
libsolv library to its Python binding will be required. This is how DNF deals with solving modular dependencies when installing and upgrading content. This effort is tracked in the sub-task #3741.