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• Launchpad Entry: deploy-dynamic-mirrors

• Packages affected: apt, launchpad

Summary

To spread the mirror load more evenly a new method in apt was developed. This spec describes what must be done to deploy this new method as default.

Release Note

TBD

Rationale

The mirror configuration is currently pretty static. It can either be dns based or static in the users sources.list. A more dynamic approach is needed to be able to deal with mirror changes quicker and to distribute the mirror load better.

Design

The new apt mirror method works by asking a server for a set of fast closeby mirrors. The current location for this is on launchpad is http://launchpad.net/ubuntu/+countrymirrors-archive

Apt uses one of those mirrors then for fetching files. It will only update the mirror information if apt-get update is called and it additinally caches them to avoid hitting the central server too hard.

To enable the new apt mirror methods as default we need to take the following steps:

1. change apt-setup to write mirror:// urls instead of http:// urls it does no longer need to write any mirror info itself

2. change the apt mirror methods to only update the mirror information only if apt sends send IndexFile=True to the methods (to ensure that Packages information is always in sync with the mirror that is downloaded from) [done]

3. Ensure that the cached mirror information is used if the main mirror is not reachable (this should be the case but needs to be tested).

Test/Demo Plan

TBD

Outstanding issues

Launchpad needs to be optimized so that the load from the users asking for mirorr information can be handled. Salgado was confident that this is possible with server side caching.

CategorySpec