Provide a better abstraction for customizing downloader behavior

[pulpbot]

Author: @dralley (dalley)

Redmine Issue: 7352, https://pulp.plan.io/issues/7352

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Customization of downloader behavior is currently achieved by subclassing one of the downloader types from the Plugin API and then modifying the get_downloader() method and downloader_factory property on the Remote (sub)class.

A limitation of this abstraction is that while the get_downloader() method accepts **kwargs to pass down to the (possibly customized) downloader, it will pass all kwargs to any downloader without discriminating by the type of downloader. Therefore it's difficult to send a kwarg to be used on a customized HTTP downloader without it being also sent to other types of downloaders such as FileDownloader which are not expecting it.

This could be worked around by additionally modifying the DownloaderFactory, but it's currently suboptimal because:

• The methods you'd want to override are underscore-prefixed (private)
• It would create extra coupling and interdependence between the classes; not the end of the world, but kind of messy

We could probably benefit from revisiting the design and incorporate some of our experience with customizing downloader behavior in various plugins.

[pulpbot]

From: @dkliban (dkliban@redhat.com) Date: 2021-01-14T15:03:24Z

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We will not get to this in the near future.

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This issue has been marked 'stale' due to lack of recent activity. If there is no further activity, the issue will be closed in another 30 days. Thank you for your contribution!

[stale[bot]]

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