The logroate.d entry for pgbouncer. Rotates the log once a day.

pgbouncer-logroate.sh

# /etc/logrotate.d/pgbouncer
/var/log/postgresql/pgbouncer.log {
    daily
    missingok
    rotate 7
    compress
    delaycompress
    notifempty
    create 640 postgres adm
    sharedscripts
    postrotate
        /usr/bin/pgrep -x pgbouncer > /dev/null && /usr/sbin/pgbouncer -R /var/run/postgresql/pgbouncer.pid
    endscript
}
# Rotate pgbouncer logs. 
# Log rotate settings details:
# Logfile location /var/log/postgresql/pgbouncer.log or /var/log/pgbouncer/pgbouncer.log
# daily: Rotate the log file daily.
# missingok: Do not output an error if the log file is missing.
# rotate 7: Keep the last 7 rotated logs.
# compress: Compress the rotated files.
# delaycompress: Delay compression of the rotated file to the next rotation cycle. This is useful in combination with compress.
# notifempty: Do not rotate the log if it is empty.
# create 640 postgres adm: Create a new log file with set permissions, owner, and group after rotation.
# sharedscripts: Run the postrotate script only once, not for each log file rotated.
# postrotate/endscript: Commands inside this block are executed after the log file is rotated. Here, 
# it checks if PgBouncer is running 
# (pgrep -x pgbouncer) 
# and sends a signal to reopen its log files 
# (/usr/sbin/pgbouncer -R or /usr/bin/pgbouncer -R depending on your install). 
# The path /var/run/postgresql/pgbouncer.pid should be replaced with the actual path 
# to your PgBouncer PID file if it's different, such as /var/run/pgbouncer/pgbouncer.pid
# Manually rotate via the command
# sudo logrotate -d /etc/logrotate.d/pgbouncer