My Apache logrotate config looks like this:

/var/log/http/*log {
    monthly
    dateext
    dateformat .%Y.%m
    [... rest stripped for brevity ...]
}

This works great, except that the date on the rotated filename is one period later than the period actually covered by the logs, for example error_log.2012.09 covers 2012-08-01 to 2012-08-31.

I realize that there are other options for Apache (eg. cronolog), but I have a bunch of other logs that I also need to rotate, and logrotate is really exactly what I need apart from this one issue.

Is there a way to get logrotate to use a date offset -- or, even better, figure out the previous time period -- when generating the rotated filename?