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How to monitor a VMware ESXi 5 / 6 host with Check_MK & OMD

Recently I posted a guide detailing how to install OMD (Open Monitoring Distribution) on Ubuntu 14.04. Part of OMD is the Check_MK network monitoring platform. I consider it the best available in the Open Source world. Check_MK supports monitoring VMware ESXi hosts, as well as vSphere servers. It uses the vSphere API to communicate with the host, so it’s able to pull much more data than SNMP. It’s not exactly a very intuitive process to get an ESXi host added to Check_MK, but it’s very easy if you know what to do. The documentation available is sub par, at best. So, I’m going to change that! This guide applies to all versions of ESXi 5 or later. So, ESXi 5, 5.1, 5.5 and 6.

Check_MK is capable of monitoring all sorts of valuable data from an ESXi host. This includes, CPU usage, RAM usage, Datastore usage, Network bandwidth statistics, health sensors and virtual machine power state.

How to add an ESXi 5, 5.1, 5.5 or 6 host to Check MK

Go ahead and log in to your Check_MK web interface. In the Configuration navigation area of the left, click on Host & Service Parameters.

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Once you are here, select “Datasource Programs.”

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Select the line that says “Check state of VMWare ESX vis vSphere.”

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You can create the rule in the Main directory, or somewhere else if you like. It doesn’t matter.

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There are three settings you need to be concerned with here.

  • Specify explicit host names
  • vSphere User name
  • vSphere secre

You should create a read-only account in ESXi / vSphere in a production environment. You can enter an FQDN, hostname, or IP in the hosts field.

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Click Save.

At the top, go ahead and click on “1 Change” and then “Activate Changes!

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Now, select “Hosts” in the configuration navigation menu on the left.

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Select “Create new host.”

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The only thing you need to do here is enter the FQDN, Hostname, or IP Address of the ESXi Host / vSphere server in the Hostname field.

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Now, click on “Save & go to Services.”

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All available sensors will be checked by default, and unless you don’t want specific items to be monitored, go ahead and click on “Save manual check configuration.”

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Now, click on “2 Changes” at the top, and then “Activate Changes!

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All done! You can click on “Hosts” under views and your ESXi host will now be listed. It will take about 3-5 minutes for it to pull all of the initial sensor data. Once is does you will be monitoring CPU, RAM, Datastores, Network Cards, Virtual Machine power state, and much much more!

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If you run into any problems, feel free to ask for help in the comments below. Thanks!