What is this?

This is a replacement for Crane (https://github.com/pulp/crane)

Crane is a docker-registry proxy that sends HTTP redirects for manifest and image layers that are stored on a CDN, so a docker pull uses the files stored in CDN. Crane does this by using metadata written by pulp.

The docker-pulp-driver is a docker registry storage driver that implements the low-level filesystem functions to emulate a registry directory structure based on the same pulp metadata files Crane uses. Actual manifest and images are read from the CDN. Because of the way registry internals work, the driver read the manifests dir ectly from CDN, but sends redirects for layer requests.

How to add this into Docker registry?

Docker registry does not support dynamic module loading as of this writing (there is a PR for that). So, we have to build a custom Docker registry to get this to work. Here are the steps:

Fork docker registry
Vendor this project in the forked copy. They use vndr, not govendor
In cmd/registry/main.go, import github.com/bserdar/docker-pulp-driver/pulp

That's sufficient to build. For configuration:

storage:
    delete:
      enabled: true
    cache:
        blobdescriptor: redis
    pulp:
        pollingdir: /var/lib/pulpmd
        pollingInterval: 60
        maxthreads: 100
    maintenance:
        uploadpurging:
            enabled: false
    redirect:
        disable: false

Here, the important things are:

storage.pulp: Tells Docker registry to use this driver
storage.redirect: Note the double-negative. This causes docker to check if driver requests a redirect for layer requests.

bserdar/docker-pulp-driver

What is this?

How to add this into Docker registry?