getdeb-collaboration team mailing list archive

[Joao Pinto <joao.pinto@xxxxxxxxxx>]

Hello,
after this long time of unavailability an also based on our current
limitation it's time to reevaluate the mirror selection strategy.

The current setup is:
On the client side:
Clients are configured to use: deb
http://archive.getdeb.net/ubuntulucid-getdeb apps games
On the server side
http://archive.getdeb.net/ubuntu/dists/... contains the repository package
list and is always retrieved from the real server (archive.getdeb.net)
http://archive.getdeb.net/ubuntu/pool/... which contains the .deb files is
handled by a PHP script which uses the mirror list and check if the file is
available at some mirror. Once a valid mirror is found the client is
redirected to it using a regular HTTP redirect.

Advantages:
- real time detection of failed servers and redirection
- ability to centrally track package downloads

Disadvantages:
- overhead of the extra http request / real time validation on a per request
basis
- single point of failure, no redirection with the master server is down

A possible alternative is to use the APT mirror: method, it will require
client's to be configure with a line like:
Add a source entry like:
deb mirror://host/path/to/mirror-list/// dist component
Add a configuration file for apt with:
Acquire::Mirror::RefreshInterval "0" <- this is required to force the target
mirror url to be obtained for each "apt-get update"

With this approach the master server is only queried once per "apt-get
update", all the subsequent transactions use the same mirror url. The
obtained mirror is cached on a local file, if the master server is
unavailable the last obtained mirror will be used.

Advantages:
- no single point of failure (except for when the master server is down and
the user did not perform any apt-get update yet)
- no overhead/overload of the master server on a per file basis

Disadvantages:
- a different method must be implemented to identify stale or unavailable
mirrors
- inability to track per file downloads
- more complex manual configuration (unusual source line and APT conf item).

Giving our present issues I think we really should try to move the the
mirror: method at this time, any comments, other ideas ?

Thanks

-- 
João Luís Marques Pinto
GetDeb Team Leader
http://www.getdeb.net
http://blog.getdeb.net