Creates EC2 snapshots of a given EBS volume and keeps around a configurable set phased over increasing intervals

  snapman.py --days=1..6d,1..3w vol-abcde

This takes a snapshot of vol-abcde and deletes all but one snapshot per day for the last week, plus two more at 2 and 3 weeks old

• for EC2 credentials, use boto's configuration files or environment variables http://code.google.com/p/boto/wiki/BotoConfig
• if you're snapshotting a volume that's mounted, make sure to wrap snapman in a script that makes the snapshot consistent (e.g. xfs_freeze or pg_start_backup)

• python 2.6+
• boto
• pytz
• python-dateutil

• don't delete snapshots that we didn't create, or at least make that the default (perhaps by checking the description prefix)
• keep snapshots mounted and accessible at /${mountpoint}/.snap/${timestamp}/ (can we do this without creating volumes out of every snapshot?)
• option to only print what snapshots would be deleted
• detect and warn that the given --days setting can't keep all of the requested backups instead of relying on --simulate