You could poll using lsof to detect when lsof no longer has the rotated file open. Not an elegant solution, but it would reliably tell you when it's safe to compress.
________________________________ From: rsyslog <[email protected]> on behalf of Jean-Baptiste Denis via rsyslog <[email protected]> Sent: Friday, August 27, 2021 16:39 To: David Lang <[email protected]>; rsyslog-users <[email protected]> Cc: Jean-Baptiste Denis <[email protected]> Subject: Re: [rsyslog] rsyslogd HUP and logrotate USE CAUTION. This message is from outside of N.C. A&T. ________________________________ Hello David, thank you for the explanation and confirmation ! So, this is a kind of gray area unless rsyslog offers some kind of blocking mechanism that do the close/reopen and exits when its done. rsyslog could also handle the rotation, but I have only seen a size criteria using outchannel (https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.rsyslog.com%2Fdoc%2Fmaster%2Ftutorials%2Flog_rotation_fix_size.html&data=04%7C01%7Casinger%40ncat.edu%7C10c250b5a98f4eefe02708d969a32328%7Cd844dd75a4d74b1fbd33bc0b1c796c38%7C0%7C0%7C637656972418202636%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=BsyPcnpd8wrbPBc6cnX9J3hTT%2FuVVoT2albLXGGtO%2BI%3D&reserved=0). I could also add a sleep X after sending the HUP in the postrotate script to achieve something similar to what you suggest. But relying on sleep to ensure that the HUP has been fully processed does not sound reliable (at least it is not satisfactory to me). Jean-Baptiste On 8/27/21 10:18 PM, David Lang wrote: > signals (like HUP) are sent and processed asynchronously, so it can take a > little bit of time to be handled. Your > understanding is correct. > > what I normally do is not use logrotate, but do the rotation myself in a > script run from cron that does the mv of the > files, sends the hub, then sleeps fora second before starting the compression > (and then normally I mv the compressed > file to a date based directory hierarchy, when you have very high log > volumes, you may want to rotate files frequently, > I've done it as frequently as every minute, and that results is LOTS of > files, more than you want in one directory) > > I don't know if this can be done in the postrotate stanza of logrotate. > > David Lang > > On Fri, 27 Aug 2021, Jean-Baptiste Denis via rsyslog wrote: > >> Date: Fri, 27 Aug 2021 16:34:51 +0200 >> From: Jean-Baptiste Denis via rsyslog <[email protected]> >> Reply-To: [email protected], rsyslog-users <[email protected]> >> To: [email protected] >> Cc: Jean-Baptiste Denis <[email protected]> >> Subject: [rsyslog] rsyslogd HUP and logrotate >> >> Hello, >> >> I've got a general question about logrotate postrotate script and rsyslogHUP >> signal handling interaction. >> >> Lets say I have this logrotate section: >> >> /var/log/messages >> { >> rotate 4 >> daily >> dateext >> missingok >> notifempty >> compress >> postrotate >> /usr/bin/systemctl kill -s HUP rsyslog.service >/dev/null 2>&1 || >> true >> endscript >> } >> >> And logrotate fires up. Something like might happen: >> >> 1. /var/log/messages is rotated to /var/log/messages-20210827 >> 2. rsyslog is still writing to /var/log/messages-20210827 >> 3. postrotate script runs, the kill signal command returns immediately >> 4. logrotate start compressing /var/log/messages-20210827 >> >> The "real" handling of SIGUP happens in rsyslogd mainloop and could happen >> anywhere after 3, which means also after 4. >> >> When the /var/log/messages activity is high (about 100 messages/sec), I >> often have logrotate compression step >> complaining about "file size changed while zipping". >> >> I can workaround this using the delaycompress option, but I'd like to >> understand if my understanding is correct and if >> there is a better/cleaner solution ? >> >> If I'm correct until this point, I can only see two options: >> >> - using delaycompress in logrotate block >> - having a command line tool that tells rsyslogd to close and reopen the log >> files AND that does not exit before >> its done and use this command in postrotate >> >> What are your thoughts ? Any suggestions ? >> >> Thank you. >> >> Jean-Baptiste >> >> >> >> >> >> _______________________________________________ >> rsyslog mailing list >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Furldefense.com%2Fv3%2F__https%3A%2F%2Flists.adiscon.net%2Fmailman%2Flistinfo%2Frsyslog__%3B!!JFdNOqOXpB6UZW0!4KbwKsaSUOggdRvK-LPY-1Q1vlVOQ26d_yxjlWF8IeLQNVAxcYLHIzJzGA9hqLmX%24&data=04%7C01%7Casinger%40ncat.edu%7C10c250b5a98f4eefe02708d969a32328%7Cd844dd75a4d74b1fbd33bc0b1c796c38%7C0%7C0%7C637656972418202636%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=K0YZjGTLX3tRKMStPHe359qu5MgxHxgPEBHuas3ewLQ%3D&reserved=0 >> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Furldefense.com%2Fv3%2F__http%3A%2F%2Fwww.rsyslog.com%2Fprofessional-services%2F__%3B!!JFdNOqOXpB6UZW0!4KbwKsaSUOggdRvK-LPY-1Q1vlVOQ26d_yxjlWF8IeLQNVAxcYLHIzJzGLbhsE0Z%24&data=04%7C01%7Casinger%40ncat.edu%7C10c250b5a98f4eefe02708d969a32328%7Cd844dd75a4d74b1fbd33bc0b1c796c38%7C0%7C0%7C637656972418202636%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=VhkhFdE7ngK0O2eON%2B8cvftRrmsoQ%2FPxisC%2B%2FsaAiQA%3D&reserved=0 >> What's up with rsyslog? 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