To monitor Apache2 on an Ubuntu server where Icinga agent is installed, while Icinga server is installed on another Ubuntu server, you can follow these step-by-step instructions. This guide assumes that Icinga 2 and Icinga Web 2 are properly installed and configured on your Icinga server, and the Icinga agent is installed and connected to your Icinga server.

Step 1: Install Necessary Plugins

On the Icinga Agent Server: Ensure you have the nagios-plugins package installed, as it includes the check for Apache. Install it using:

$ sudo apt-get update
$ sudo apt-get install nagios-plugins

Step 2: Configure Icinga Agent

Check the Apache Status Module: Make sure that the Apache status module is enabled on the Apache server. You can enable it with:


$ sudo a2enmod status
$ sudo systemctl restart apache2

Ensure the /etc/apache2/mods-enabled/status.conf is configured to allow access from the Icinga server IP. It might look something like this:


<Location /server-status>
    SetHandler server-status
    Require local
    Require ip 192.168.x.x  # IP of your Icinga server
</Location>

Configure the Agent: On the Icinga agent, ensure it can execute the Apache check. You might need to create a command in Icinga if it doesn’t exist:

object CheckCommand "check_apache_status" {
    import "plugin-check-command"
    command = [ PluginDir + "/check_http" ]
    arguments = {
        "-H" = "$address$"
        "-u" = "/server-status?auto"
    }
}

Step 3: Configure Icinga Server

Define the Host Object: If you haven't already defined the host object for the Apache server in your Icinga configuration, add it:

object Host "apache-server" {
    import "generic-host"
    address = "apache-agent-ip"
    check_command = "hostalive"
}

Define Service for Apache Monitoring: Create a service definition to check Apache status:

apply Service "apache-status" {
    import "generic-service"
    check_command = "apache_status"
    vars.address = "$host.address$"
    assign where host.name == "apache-server"
}

OR

apply Service "apache-status" {
    import "generic-service"
    check_command = "http"
    vars.address = "$host.address$"
    assign where host.name == "apache-server"
}

Reload Icinga 2: After making changes to the configuration files, reload the Icinga 2 service to apply the changes:

sudo systemctl reload icinga2

Step 4: Verify the Configuration

Icinga Web 2: Log into Icinga Web 2 and navigate to the 'Services' section. You should see your new service for monitoring Apache. Verify that it is checking the status as expected.

Troubleshooting: If there are issues, check the Icinga 2 logs for any errors related to the Apache checks. The logs are usually located in /var/log/icinga2/icinga2.log.

	=====================================================
	Step 1 - Install icinga2 in Agent Server
	=====================================================
	8 apt update
	9 apt -y install apt-transport-https wget gnupg
	10 wget -O - https://packages.icinga.com/icinga.key | gpg --dearmor -o /usr/share/keyrings/icinga-archive-keyring.gpg
	11 . /etc/os-release; if [ ! -z ${UBUNTU_CODENAME+x} ]; then DIST="${UBUNTU_CODENAME}"; else DIST="$(lsb_release -c| awk '{print $2}')"; fi; echo "deb [signed-by=/usr/share/keyrings/icinga-archive-keyring.gpg] https://packages.icinga.com/ubuntu icinga-${DIST} main" > /etc/apt/sources.list.d/${DIST}-icinga.list
	12 apt update
	13 apt install icinga2
	14 apt install monitoring-plugins
	=====================================================
	Step 2 - Enable icinga2 Agent
	=====================================================
	root@ip-172-31-4-57:~# icinga2 node wizard
	Welcome to the Icinga 2 Setup Wizard!
	We will guide you through all required configuration details.
	Please specify if this is an agent/satellite setup ('n' installs a master setup) [Y/n]: Y
	Starting the Agent/Satellite setup routine...
	Please specify the common name (CN) [ip-172-31-4-57.ap-south-1.compute.internal]:
	Please specify the parent endpoint(s) (master or satellite) where this node should connect to:
	Master/Satellite Common Name (CN from your master/satellite node): ip-172-31-12-175.ap-south-1.compute.i nternal
	Do you want to establish a connection to the parent node from this node? [Y/n]: Y
	Please specify the master/satellite connection information:
	Master/Satellite endpoint host (IP address or FQDN): 172.31.12.175
	Master/Satellite endpoint port [5665]:
	Add more master/satellite endpoints? [y/N]: N
	Parent certificate information:
	Version: 3
	Subject: CN = ip-172-31-12-175.ap-south-1.compute.internal
	Issuer: CN = Icinga CA
	Valid From: May 10 04:17:19 2024 GMT
	Valid Until: Jun 11 04:17:19 2025 GMT
	Serial: f0:c6:d1:1c:f0:78:1b:6b:2d:7c:20:4b:1b:50:3c:be:f0:25:a2:17
	Signature Algorithm: sha256WithRSAEncryption
	Subject Alt Names: ip-172-31-12-175.ap-south-1.compute.internal
	Fingerprint: 54 FD AD AC 55 39 7F 7A 5F C2 2D BB 09 22 BE 43 08 15 FB DF 0D F6 5C 2B 76 15 0F C 1 DD 29 00 7B
	Is this information correct? [y/N]: y
	Please specify the request ticket generated on your Icinga 2 master (optional).
	(Hint: # icinga2 pki ticket --cn 'ip-172-31-4-57.ap-south-1.compute.internal'): 94deed8004eefccb459689dbc6fe1112543b01eb
	Please specify the API bind host/port (optional):
	Bind Host []:
	Bind Port []:
	Accept config from parent node? [y/N]: y
	Accept commands from parent node? [y/N]: y
	Reconfiguring Icinga...
	Disabling feature notification. Make sure to restart Icinga 2 for these changes to take effect.
	Enabling feature api. Make sure to restart Icinga 2 for these changes to take effect.
	Local zone name [ip-172-31-4-57.ap-south-1.compute.internal]:
	Parent zone name [master]:
	Default global zones: global-templates director-global
	Do you want to specify additional global zones? [y/N]:
	Do you want to disable the inclusion of the conf.d directory [Y/n]: n
	Done.
	Now restart your Icinga 2 daemon to finish the installation!\
	$ systemctl restart icinga2
	=====================================================
	Step 3 - Install Apache 2
	=====================================================
	26 apt-get update
	27 apt install apache2
	28 clear
	29 ls
	30 systemctl start apache2
	31 systemctl status apache2
	=====================================================
	Step 4 - Verify if Mod_Staus module in Apache2
	=====================================================
	$ ls /etc/apache2/mods-enabled | grep status*
	status.conf
	status.load
	$ sudo /usr/sbin/a2enmod status
	Module status already enabled
	Note - If you want to enable - follow this - https://www.devopsschool.com/blog/how-to-install-mod_status-on-your-apache-servers-and-enable-extendedstatus/
	=====================================================
	Step 5 - Enable Mod Status Module from icinga server
	=====================================================
	$ more /etc/apache2/mods-enabled/status.conf
	$ vi /etc/apache2/mods-enabled/status.conf
	$ systemctl restart apache2
	<IfModule mod_status.c>
	# Allow server status reports generated by mod_status,
	# with the URL of http://servername/server-status
	# Uncomment and change the "192.0.2.0/24" to allow access from other hosts.
	<Location /server-status>
	SetHandler server-status
	Require local
	Require ip 172.31.12.175
	</Location>
	# Keep track of extended status information for each request
	ExtendedStatus On
	# Determine if mod_status displays the first 63 characters of a request or
	# the last 63, assuming the request itself is greater than 63 chars.
	# Default: Off
	#SeeRequestTail On
	<IfModule mod_proxy.c>
	# Show Proxy LoadBalancer status in mod_status
	ProxyStatus On
	</IfModule>
	</IfModule>
	=====================================================
	Step 6 - Enable Apache check in Icinga Server
	=====================================================
	49 cd /etc/icinga2/conf.d/
	50 ls
	51 vi commands.conf
	object CheckCommand "check_apache_status" {
	import "plugin-check-command"
	command = [ PluginDir + "/check_http" ]
	arguments = {
	"-H" = "$address$"
	"-u" = "/server-status?auto"
	}
	}
	OR
	object CheckCommand "check_apache_status" {
	import "plugin-check-command"
	command = [ PluginDir + "/check_http" ]
	arguments = {
	"-H" = "172.31.4.57"
	"-u" = "/server-status?auto"
	}
	}
	$ systemctl restart icinga2
	$ systemctl status icinga2

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