What to do if nginx is down

nginx troubleshooting steps: Check nginx status and error log Restart nginx Check syntax errors and invalid settings in configuration files Check file descriptors and memory usage restrictions Check security groups and firewall rules Check whether nginx processes hang Check file system available space Check third-party module installation and stability Troubleshoot hardware issues

nginx downtime troubleshooting

1. Determine the problem

• Use systemctl status nginx to check the status of nginx.
• View error messages in /var/log/nginx/error.log .

2. Restart nginx

• Use systemctl restart nginx to try restart nginx.
• If the restart fails, use journalctl -xe to check the details.

3. Check configuration issues

• Check the configuration file in /etc/nginx/nginx.conf to make sure there are no syntax errors or invalid settings.
• Pay special attention to server , listen and root instructions.

4. Check resource limitations

• Use ulimit -n to check the limitations of file descriptors. nginx requires 1024 by default.
• Use free -m to check memory usage.

5. Check the security group

• Ensure that nginx's security group allows incoming connections from the client.
• Check if the firewall rules are not blocking nginx.

6. Check the process hangs

• Use ps auxf | grep nginx to check if the nginx process is suspended.
• If the process hangs, use gstack <pid></pid> to get the stack trace.

7. Check for file system failures

• Use df -h to check the free space of nginx logs and configuration directories.
• If there is insufficient space, consider clearing old logs or upgrading to a larger file system.

8. Check third-party modules

• If nginx uses third-party modules, make sure they are installed correctly.
• Disable suspicious modules or fall back to a stable version.

9. Check for hardware problems

• If all software issues are excluded, check the server hardware for failures.
• Restart the server or contact the system administrator for help.

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