Monitoring Docker containers on an Ubuntu server using Icinga involves setting up the Icinga agent to execute Docker-specific monitoring checks and configuring the Icinga server to process and display these checks. Here is a step-by-step guide to achieve this.

Step 1: Install Docker Monitoring Plugin

On the Icinga Agent Server: You need to have a plugin that can monitor Docker. One common choice is the check_docker plugin, which can be found on GitHub. You will have to manually download and install this plugin.

$ cd /usr/lib/nagios/plugins
$ sudo wget https://exchange.icinga.com/elacheche/Docker%20containers%20check/files/12915/docker_check.py
$ sudo chmod +x docker_check.py

Install Python and Docker SDK for Python: The check_docker plugin requires Python and the Docker SDK for Python.

$ sudo apt-get update
$ sudo apt-get install python3 python3-pip
$ sudo pip3 install docker

Step 2: Configure Icinga Agent

Add Command Definitions: You need to define a command in Icinga for the Docker check. Create or edit a configuration file in the Icinga agent:

sudo nano /etc/icinga2/conf.d/commands.conf
Add the following definition:

object CheckCommand "docker_check" {
    command = [ "/usr/bin/python3", "/usr/lib/nagios/plugins/docker_check.py" ]
    arguments = {
        "--containers" = "$docker_containers$"
        "--stats" = "$docker_stats$"
    }
}

Step 3: Configure Icinga Server

Define Host Object: If not already done, define the host object for the Docker server in your Icinga server configuration:

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

Define Service for Docker Monitoring: Create a service definition to monitor Docker:

apply Service "docker-status" {
    import "generic-service"
    check_command = "docker_check"
    vars.docker_containers = "all"
    vars.docker_stats = "true"
    assign where host.name == "docker-server"
}

Reload Icinga 2: After configuring the service and command, reload Icinga 2 to apply the changes:

$ sudo systemctl reload icinga2

Step 4: Verify the Configuration

Icinga Web 2: Log into Icinga Web 2 and check the 'Services' section. You should see your new service for monitoring Docker. Ensure that it is reporting the status of Docker containers as expected.

Troubleshooting: If the checks aren't working as expected, look at the logs in /var/log/icinga2/icinga2.log for any errors. Check the permissions of the check_docker.py script and ensure that the Icinga user can execute it and has access to Docker via the Docker group.

Rajesh Kumar

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