Use an incremental upload/manifest based approach for GCB

[dlorenc]

The manifest downloader is now an official build step: https://github.com/GoogleCloudPlatform/cloud-builders/tree/master/gcs-fetcher

We should consider using this combined with an incremental upload approach to make GCB builds faster.

[imjasonh]

There's a library encapsulating manifest upload too, which Skaffold can use: https://github.com/GoogleCloudPlatform/cloud-builders/blob/master/gcs-fetcher/pkg/uploader/uploader.go

[imjasonh]

It looks like incremental upload (and maybe download?) could be used in kaniko-based builds as well, which specify gcsBucket.

[dgageot]

Hi everyone, I'm going to close this one since we didn't see a lot of demand and we do not plan on working on that subject anytime soon. Feel free to reopen if you really want that feature to be implemented.