[darc/maestro++] Allow subscriptions to filter on dependencies

[mmitche]

Subscriptions today are all or nothing. When a build comes in, all assets that apply the target repo/branch will be applied. This is fine most of the time, but we have a few cases where we want to flow specific assets.

For example, let's say that we produce an OOB package in corefx in 3.0, but want to use it in 3.1 and 5.0 (not shipping a new package there). We can set up a subscription between the 3.0 channel and 3.1 and 5.0 branches that will flow this dependency, but it will also flow outputs that are also being produced in the 3.1 and 5.0 branches, overwriting them.

What you really want to do is to flow only dependency A from channel X, and all other dependencies from channel Y.

[mmitche]

/cc @dsplaisted

[riarenas]

@mmitche do you think we need this for NET5? moving there for now.

[dsplaisted]

For the CLI team, we'd like this as soon as possible. Currently we are handling this via time-consuming, error-prone processes.

[riarenas]

Keeping it for the .NET 5 time frame then. Thanks for the context @dsplaisted

[wli3]

Any update on this issue?

[JohnTortugo]

Not yet. :-(

[riarenas]

This didn't make the cut for .NET 5. Moving to continuation epic