Log rotation in Nginx - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Nginx logrotate configuration effect

Given this logrotate configuration snippet for nginx logs, what will happen after logrotate runs?

/var/log/nginx/*.log {
  daily
  missingok
  rotate 7
  compress
  delaycompress
  notifempty
  create 0640 www-data adm
  sharedscripts
  postrotate
    systemctl reload nginx > /dev/null 2>/dev/null || true
  endscript
}

A Logs are rotated weekly, keeping 7 uncompressed old logs, nginx is restarted after rotation.

B Logs are rotated daily, keeping 7 compressed old logs, nginx is reloaded after rotation.

C Logs are rotated daily, old logs are deleted immediately, nginx is stopped after rotation.

D Logs are rotated monthly, keeping 30 compressed old logs, nginx is reloaded before rotation.

💡 Hint

Look at the keywords 'daily', 'rotate 7', 'compress', and 'postrotate' commands.

This configuration rotates nginx logs daily, keeps 7 old logs compressed (due to 'compress' and 'delaycompress'), and reloads nginx after rotation to reopen log files.

❓ Troubleshoot

intermediate

Nginx logs not rotating as expected

You configured logrotate for nginx logs but notice logs are not rotating daily as expected. Which of these is the most likely cause?

A The logrotate cron job is not running or disabled on the system.

B The nginx service is running and does not allow log rotation.

C The log files are empty, so logrotate refuses to rotate them.

D The logrotate configuration file has 'weekly' instead of 'daily'.

💡 Hint

Check if the system is actually running the logrotate commands automatically.

If the cron job or systemd timer that runs logrotate is not active, logs won't rotate regardless of configuration.

❓ Configuration

advanced

Configure logrotate to keep logs for 14 days and compress immediately

Which logrotate configuration snippet correctly rotates nginx logs daily, keeps 14 compressed old logs, and compresses logs immediately after rotation?

A

/var/log/nginx/*.log {
  weekly
  rotate 14
  compress
  delaycompress
  notifempty
  create 0640 www-data adm
  sharedscripts
  postrotate
    systemctl reload nginx > /dev/null 2>/dev/null || true
  endscript
}

B

/var/log/nginx/*.log {
  daily
  rotate 14
  compress
  delaycompress
  notifempty
  create 0640 www-data adm
  sharedscripts
  postrotate
    systemctl reload nginx > /dev/null 2>/dev/null || true
  endscript
}

C

/var/log/nginx/*.log {
  daily
  rotate 7
  compress
  delaycompress
  notifempty
  create 0640 www-data adm
  sharedscripts
  postrotate
    systemctl reload nginx > /dev/null 2>/dev/null || true
  endscript
}

D

/var/log/nginx/*.log {
  daily
  rotate 14
  compress
  notifempty
  create 0640 www-data adm
  sharedscripts
  postrotate
    systemctl reload nginx > /dev/null 2>/dev/null || true
  endscript
}

💡 Hint

Immediate compression means no 'delaycompress' option.

Option D rotates daily, keeps 14 compressed logs, and compresses immediately because it lacks 'delaycompress'.

✅ Best Practice

advanced

Recommended action after log rotation for nginx

After rotating nginx logs, what is the recommended action to ensure nginx writes to new log files?

A Do nothing; nginx automatically detects rotated logs.

B Restart the nginx service to apply log rotation changes.

C Reload the nginx service to reopen log files without downtime.

D Delete old log files manually to free disk space.

💡 Hint

Consider how nginx handles open file descriptors after log rotation.

Reloading nginx causes it to reopen log files without stopping the service, which is best practice after log rotation.

🧠 Conceptual

expert

Understanding delaycompress in logrotate

What is the main reason to use the 'delaycompress' option in nginx logrotate configuration?

A To delay compression until the next rotation cycle, ensuring the most recent rotated log remains uncompressed for immediate access.

B To compress logs immediately after rotation to save disk space right away.

C To delay log rotation until the log file reaches a certain size.

D To prevent compression of any rotated logs permanently.

💡 Hint

Think about why you might want the newest rotated log to stay uncompressed temporarily.

'delaycompress' keeps the most recent rotated log uncompressed until the next rotation, which helps processes that might still be writing or reading that file.