Nagios Core 4.3.4自定义配置生效异常：Web界面未更新

Problem Background #

You've completed the following custom configuration steps for Nagios Core 4.3.4:

1. Added these lines to /usr/local/nagios/etc/nagios.cfg:

   cfg_file=/usr/local/nagios/etc/objects/newhost.cfg
   cfg_dir=/usr/local/nagios/etc/servers
   

2. Created /usr/local/nagios/etc/servers/ubuntu_host.cfg with:

   define host {
       use linux-server
       host_name ubuntu_host
       alias Ubuntu Host
       address 192.168.1.10
       register 1
   }
   

3. Created /usr/local/nagios/etc/objects/newhost.cfg with:

   # Define a host for the local machine
   define host{
       use linux-server
       host_name google.com
       alias google.com
       address www.google.com
   }
   # Define a service to "ping" the local machine
   define service{
       use generic-service
       host_name google.com
       service_description PING
       check_command check_ping!100.0,20%!500.0,60%
   }
   define service{
       use generic-service
       host_name google.com
       service_description HTTP
       check_command check_http
       notifications_enabled 0
   }
   

The pre-flight check passed successfully, detecting 3 hosts:

Running pre-flight check on configuration data...
Checking objects...
Checked 7 services.
Checked 3 hosts.
Checked 0 host groups.
Checked 0 service groups.
Checked 1 contacts.
Checked 1 contact groups.
Checked 24 commands.
Checked 5 time periods.
Checked 0 host escalations.
Checked 0 service escalations.
Checking for circular paths...
Checked 3 hosts
Checked 0 service dependencies
Checked 0 host dependencies
Checked 5 timeperiods
Checking global event handlers...
Checking obsessive compulsive processor commands...
Checking misc settings...
Total Warnings: 0
Total Errors: 0

You've restarted nrpe, nagios, and httpd services, but the Nagios Web UI still shows only the original information and hasn't loaded the new configurations.

Troubleshooting Steps #

1. Verify Nagios Service Actually Loaded the New Config

Don't rely solely on the restart command's exit code—dig deeper to confirm:

• Check the service status directly:

  # For systemd-based systems
  systemctl status nagios
  # For SysVinit systems
  service nagios status
  

  Look for "active (running)" in the output, and scan recent logs for any startup errors.
• Inspect the Nagios log file (default path: /usr/local/nagios/var/nagios.log):

  tail -20 /usr/local/nagios/var/nagios.log
  

  Look for entries like Successfully reloaded configuration. If this line is missing, the log will likely detail why the config failed to load.

2. Clear Browser Cache

Browsers often cache old UI content—this is one of the most overlooked fixes:

• Force-refresh the page: Use Ctrl+F5 (Windows/Linux) or Cmd+Shift+F5 (Mac)
• Open the Nagios UI in incognito/private browsing mode to bypass local cache entirely

3. Fix Configuration File Permissions

The Nagios user (typically nagios) needs read access to all your custom config files. Even if the pre-flight check passes, missing permissions will block the service from loading them:

• Check current permissions:

  ls -l /usr/local/nagios/etc/servers/ubuntu_host.cfg /usr/local/nagios/etc/objects/newhost.cfg
  

• Correct permissions if needed:

  chown nagios:nagios /usr/local/nagios/etc/servers/*.cfg /usr/local/nagios/etc/objects/newhost.cfg
  chmod 644 /usr/local/nagios/etc/servers/*.cfg /usr/local/nagios/etc/objects/newhost.cfg
  

  Restart Nagios after making these changes.

4. Validate Web UI User Permissions

If you're not logged in as the default nagiosadmin, your user might lack access to the new hosts/services:

• Confirm your user's contact group is associated with the new hosts. For example, your google.com host inherits settings from the linux-server template—check that the template's contact_groups includes your user's group.
• For nagiosadmin, verify the contacts.cfg file correctly links them to the admin contact group (which should have full access to all objects).

5. Double-Check Config Inclusion in nagios.cfg

Reconfirm your nagios.cfg settings to ensure files are being included properly:

• Make sure cfg_file=/usr/local/nagios/etc/objects/newhost.cfg is not commented out (no leading #)
• Ensure cfg_dir=/usr/local/nagios/etc/servers points to an existing directory, and all files inside have a .cfg extension (Nagios ignores non-.cfg files in cfg directories)

6. Trigger a Manual Config Reload

Sometimes standard restart commands don't work as expected—try a direct reload:

1. Re-run the pre-flight check to confirm config validity:

   /usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
   

2. Manually reload or start Nagios:

   # Systemd
   systemctl reload nagios
   # SysVinit
   service nagios reload
   # Or manual start command
   /usr/local/nagios/bin/nagios -d /usr/local/nagios/etc/nagios.cfg
   

内容的提问来源于stack exchange，提问作者Frodogus