Manipulate date

logrotate

/var/log/myproject/celery.log {
    size 1
    su myuser myuser
    copytruncate
    create
    rotate 10
    missingok
    postrotate
        timeext=`date -d '1 day ago' "+%Y-%m-%d"`  # daily
#        timeext=$(date +%Y-%m-%d_%H)  # hourly
        mv /var/log/myproject/celery.log.1 /var/log/myproject/archive/celery_$timeext.log
    endscript
}