Nginx-exporter docker version - issue when access.log rotate

[dec21raj]

Hi Team,

First of all Thank you very much for the software.

I installed RPM of this software on CentOS 7.x which works great.
Few of my server are running with "Scientific Linux release 6.7 (Carbon)" where systemd is not supported. So I tried to use Docker version of this software.

Issue I am noticing, when access.log file rotates, exporter stop reading the contents from access.log
Am I running docker instance in a wrong way ?

docker run -d
--name nginx-exporter
-v /var/log/nginx/access.log:/var/log/nginx/access.log
-v /etc/prometheus/prometheus-nginxlog-exporter.hcl:/etc/prometheus/prometheus-nginxlog-exporter.hcl
-p 4040:4040
quay.io/martinhelmich/prometheus-nginxlog-exporter
-config-file /etc/prometheus/prometheus-nginxlog-exporter.hcl

[martin-helmich]

In general, this should not happen, and I've used this exporter with log rotation successfully. I this this might possibly be related as to how exactly the access log file is rotated. Let me do some digging and get back to you on this. ⏳

[dec21raj]

Thanks Martin.
Please let me know if you need additional information.

NGINX Logrotate config pasted blow.

cat /etc/logrotate.d/nginx
/var/log/nginx/*.log {
daily
missingok
rotate 52
compress
delaycompress
notifempty
create 640 nginx adm
sharedscripts
postrotate
if [ -f /var/run/nginx.pid ]; then
kill -USR1 cat /var/run/nginx.pid
fi
endscript
}

[martin-helmich]

You could try using the copytruncate option.

[dec21raj]

Thanks Martin. That helped.
Looks like its limitation of docker, which can't load the new log file created where inode got changed after rotation.