When logrotate fails to automatically rotate MySQL slow logs despite proper configuration, we need to systematically examine several aspects. Here's the configuration in question:

/var/log/mysql/mysql-slow.log {
    daily
    rotate 3
    compress
    notifempty
    missingok
    create 660 mysql adm
    postrotate 
    if test -x /usr/bin/mysqladmin && \
       /usr/bin/mysqladmin ping &>/dev/null
    then
       /usr/bin/mysqladmin flush-logs
    fi
    endscript
}

First, let's verify the basic requirements:

# Check log file existence
ls -la /var/log/mysql/mysql-slow.log

# Test mysqladmin command manually
/usr/bin/mysqladmin ping

# Verify file permissions
stat /var/log/mysql/mysql-slow.log

The most critical place to check is the logrotate execution log. On Ubuntu systems, this is typically located at:

/var/log/syslog
/var/log/cron.log

Search for logrotate entries with:

grep logrotate /var/log/syslog
grep CRON /var/log/syslog | grep -i logrotate

When testing manually, always use verbose flags:

logrotate -vf /etc/logrotate.d/mysql-slow

The -v flag provides verbose output, while -f forces rotation regardless of schedule.

Here are some common issues and their solutions:

# 1. Permission issues
chown mysql:adm /var/log/mysql/mysql-slow.log
chmod 660 /var/log/mysql/mysql-slow.log

# 2. Missing cron job
cat /etc/cron.daily/logrotate

# 3. Test postrotate script independently
if test -x /usr/bin/mysqladmin && \
   /usr/bin/mysqladmin ping &>/dev/null
then
   /usr/bin/mysqladmin flush-logs
fi

For more robust logging, consider this enhanced configuration:

/var/log/mysql/mysql-slow.log {
    daily
    rotate 7
    compress
    delaycompress
    missingok
    notifempty
    create 660 mysql adm
    sharedscripts
    postrotate
        # More robust version with error logging
        if [ -x /usr/bin/mysqladmin ]; then
            if /usr/bin/mysqladmin ping > /dev/null 2>&1; then
                /usr/bin/mysqladmin flush-logs >> /var/log/mysql/logrotate.log 2>&1
            else
                echo "$(date): MySQL not running" >> /var/log/mysql/logrotate.log
            fi
        else
            echo "$(date): mysqladmin not found" >> /var/log/mysql/logrotate.log
        fi
    endscript
}

To better track rotation attempts, add this to your rsyslog configuration:

# /etc/rsyslog.d/10-logrotate.conf
if $programname == 'logrotate' then /var/log/logrotate.log
& stop

This will capture all logrotate activity in a dedicated file.

---

When logrotate fails to rotate MySQL slow query logs despite correct configuration, we need to examine several technical aspects. Your configuration appears valid, but let's systematically verify each component.

# Confirmed log file exists
ls -la /var/log/mysql/mysql-slow.log

# Verified mysqladmin works
/usr/bin/mysqladmin ping
/usr/bin/mysqladmin flush-logs

# Checked file permissions
stat /var/log/mysql/mysql-slow.log

Your manual test with logrotate -d -f worked, which indicates the configuration is syntactically correct. The main suspects become:

1. Logrotate Execution Timing

# Check when logrotate runs
cat /etc/cron.daily/logrotate

# Verify last execution time
grep logrotate /var/log/syslog | tail -n 5

2. Permission Issues During Cron Execution

The cron job might run with different permissions than your manual test:

# Create test script
echo '#!/bin/bash
whoami
/usr/sbin/logrotate -v /etc/logrotate.conf' > /tmp/logrotate_test.sh
chmod +x /tmp/logrotate_test.sh

# Run as cron would
sudo -u nobody /tmp/logrotate_test.sh

Here's a more robust version of your configuration with additional debugging:

/var/log/mysql/mysql-slow.log {
    daily
    rotate 3
    compress
    delaycompress
    notifempty
    missingok
    create 660 mysql adm
    sharedscripts
    postrotate
        logger -t logrotate "Rotating MySQL slow log"
        if [ -x /usr/bin/mysqladmin ]; then
            /usr/bin/mysqladmin ping &>/dev/null && \
            /usr/bin/mysqladmin flush-logs || \
            logger -t logrotate "MySQL flush-logs failed"
        fi
    endscript
}

To capture what happens during automatic rotation:

# Method 1: Force run with debug
sudo /usr/sbin/logrotate -vf /etc/logrotate.d/mysql-slow

# Method 2: Add verbose logging
*/5 * * * * root /usr/sbin/logrotate -v /etc/logrotate.d/mysql-slow >> /var/log/logrotate.debug 2>&1

• selinux Context: ls -Z /var/log/mysql/
• Inode Changes: Some applications require special handling
• Disk Space: Check with df -h /var/log

After implementing changes, monitor for rotation:

watch -n 60 'ls -l /var/log/mysql/mysql-slow.log*'