https://github.com/activestate/static-docker-registry

Experiments in making 'docker pull' reliable
https://github.com/activestate/static-docker-registry

Last synced: 4 months ago
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Experiments in making 'docker pull' reliable

• Host: GitHub
• URL: https://github.com/activestate/static-docker-registry
• Owner: ActiveState
• License: mit
• Created: 2014-04-03T23:40:32.000Z (about 12 years ago)
• Default Branch: master
• Last Pushed: 2014-04-04T19:03:53.000Z (about 12 years ago)
• Last Synced: 2025-10-09T02:42:50.433Z (9 months ago)
• Language: Go
• Homepage:
• Size: 203 KB
• Stars: 12
• Watchers: 50
• Forks: 4
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          
static-docker-registry

======================

This is a demonstration of making 'docker pull' more reliable.

Pull is made realible by having it fetch the image layers (and metadata) *directly* 

from the CDN instead of having to go throughly the comparably unreliable registry 

middleman.

![](diagram.png)

In order to achieve this, we need four things:

1. [patch docker](https://github.com/dotcloud/docker/pull/4607) to make it ignore the 

   special X-* http headers if not present, even though it is not strictly required if 

   we add the headers to the endpoint app (see point 3).

2. [patch

   docker-registry](https://github.com/ActiveState/docker-registry/compare/static-registry)

   to store 'tags' and 'images' files under each repositority. this allows the

   docker client to directly request /tags and /images from the CDN. the /tags

   file in particular is required as it is not possible to enumerate the /tag_*

   files from the registry store. the patched version is available as a docker image -

   `docker pull srid/static-docker-registry`

3. the [endpoint web

   app](https://github.com/ActiveState/static-docker-registry/blob/master/endpoint) - a simple

   redirecting http proxy server that redirects on incoming requests to the CDN.

4. A distributed and reliable data store like openstack swift (or amazon s3) for use as the

   storage backend in docker-registry. the data files must be made publicly available via http 

   for use in the endpoint app.

Now what happens when you one runs 'docker pull' is:

* /v1/_ping is requested, and endpoint returns a 200 response

* docker proceeds to fetch metadata and layers

* for every request therein, the endpoint will respond with a http redirect to

  the corresponding CDN file.

* docker respects the redirect response, and fetches from the CDN.

As a result, 'docker pull' is made more reliable as it doesn't rely on a

registry middleman at all. The endpoint app is still useful as a federation

server so that "docker pull /foo/myimg" knows where to go to

get the images from.