Are variables supported in logrotate configuration files?

Question

I looked at logrotate.conf examples and everything in my /etc/logrotate.d directory. Nowhere was I able to find documentation on variables in these files.

I am trying to create a config file for rotating the logs of an application we are writing. I want to set the directory where logs are stored once, and then use it as a variable, like so:

my_app_log_dir=/where/it/is/deployed/logs

${my_app_log_dir}/*.log ${my_app_log_dir}/some_sub_dir/*.log {
    missingok
    # and so on
    # ...
}

Is that possible?

score 11 · Answer 1 · answered Dec 11 '10 at 14:23

You can achieve what you are looking for by implementing this kludge:

my-logrotate.conf ( NOTE: double quotes " are mandatory, also note that file names don't have to appear on the same line )

"*.log"
"some_sub_dir/*.log"
{
    missingok
    # and so on
    # ...
}

Then the actual logrotate script - my-logrotate.sh

#!/bin/sh

set -eu

cd "${my_app_log_dir}"
exec logrotate /path/to/my-logrotate.conf

Now you can add logrotate.sh to your crontab.

score 5 · Answer 2 · answered Mar 23 '16 at 09:35

You can use a bash "here document" to create a suitable config file on the fly, either at installation time or before running logrotate.

A bash script might look like this:

cat >rt.conf <<.
"${my_app_log_dir}/*.log" {
    rotate 5
    size 15k
    missingok
}
.

logrotate  rt.conf

score 1 · Answer 3 · answered Nov 19 '09 at 09:24

Directly in the config file no (as far as my knowledge in logrotate goes).

Other solution:

Use the include option to include parts of the configuration file from a directory. This can help you if you have a package for your application, the package can leave a file in that directory containing only the entries for your app.

score 1 · Answer 4 · answered Jul 27 '20 at 21:20

With logrotate 3.8.7,a test reveals that you can set and use variables in the pre-rotate and post-rotate script sections.

I tried this for a particular service log file.

   postrotate
         pid_file="/run/some_service/some_serviced.pid"
         test -e "${pid_file}" && kill -s HUP $(cat "${pid_file}") || true
         touch "${pid_file}.WAS_USED"
   endscript

After running logrotate in force mode to ensure the log file was rotated and the post-rotate script executed, on looking in /run/some_service, there was an additional file "some_serviced.pid.WAS_USED", thus proving that the use of the variable worked.

Are variables supported in logrotate configuration files?

4 Answers4