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Custom notification and automation based on host failure in VMware Cloud on AWS

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Physical hardware failure is inevitable, this is true whether it is running in your on-premises datacenter or in the Cloud like VMware Cloud on AWS. Although vSphere HA will automatically restart all affected VMs after detecting a host failure, there is usually additional activities that must be performed by a customer such as notifying all impacted application owners and even creating an incident ticket for hardware replacement.

With VMware Cloud on AWS, the hardware replacement is done automatically for you but the downstream activity of notifying application owners to verify the application is functional is still managed by the customer. There are many ways in how customers can manage such incidents and one solution that I am a huge advocate of is taking advantage of the powerful vCenter Server Events, which has over 1700+ events, not to mention any of the 2nd/3rd party events.

When an ESXi host fails, the com.vmware.vc.HA.DasHostFailedEvent event will be generated which contains all the relavent information related to the host failure including the specific hostname/IP, when the incident occurred and details about the vSphere Cluster and Datacenter is also provided. This information is visible using the vSphere UI but it can also be programmatically retrieved using the vSphere API, which is how the vSphere UI renders this information.

Note: Everything described in this blog post including the VEBA example is applicable to any environment that contains vCenter Server and is not limited to just VMware Cloud on AWS.

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Configuring dnsmasq as PXE Server for ESXi 

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One really cool thing that I came to learn while setting up the infrastructure to network boot the latest Raspberry Pi 4 was the use of dnsmasq, which I have used in the past but I did not realize it could do so much more. In addition to providing DNS services, it can also be configured to run TFTP and provide DHCP capabilities which can then be used to support PXE installations.

Another neat feature of dnsmasq is ability to proxy to an existing DHCP server which is extremely useful for anyone with an existing DHCP infrastructure. Given the simplicity of dnsmasq and having already set this up for the rPI, I figure it would also be useful to take folks through in setting up dnsmasq to also support ESXi installations over PXE, since this still comes up from new folks just getting started with ESXi kickstart automation.

For more details about PXE installation of ESXi, I highly recommend this whitepaper and although it states 6.0, the concepts and configurations are still applicable to the latest ESXi 7.0 release.

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Two methods to network boot Raspberry Pi 4

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My Raspberry Pi 4 (8GB) model just came last week and after completing my RADIO (VMware's R&D Innovation Offsite) session recording, I wanted to setup my new rPI so I can start playing with it when I had some spare time. I also have the 4GB model but it was running quite hot as I was using the default case (do not recommend) and decided to put that aside for now. I ended up purchasing the 8GB model from Canakit which includes additional heatsinks and nice built-in fan with their custom case.

After spending some time setting up the rPI OS and applying the various updates, I was not too keen on using the SD Card, especially as some folks on forums mentioned that it can easily be worn out depending on the type of workload. While researching online and some references pointed out by colleagues, I came to learn that in addition to booting from USB which is now possible with rPI, you can also network boot the rPI without an SD Card or any storage for that matter! This immediately resonated with me, especially as I am a huge fan of scripted installations such as Kickstart/Jumpstart.

Here are all the resources that I had used that provided all the heavy lifting. I have optimized some of the commands to make it easy for anyone to simply copy and past who is new to setting up an rPI. The authors below did a fantastic job in outlining all the details, so I highly recommend a read if you would like to get more information. I also will be going over an alternative method at the end for booting the rPI over the network which is not really talked about.

One really cool thing that I came to learn while setting up the infrastructure to network boot an rPI was the use of dnsmasq, which I have used in the past but I did not realize it could do so much more. I may have spent more time playing with dnsmasq than with the rPI itself and I will probably cover this in another blog post on how you can easily setup a PXE/gPXE/iPXE system to enable automated OS installation (e.g. Kickstart) that can be used with ESXi or any other OS for that support network installations via BIOS/UEFI.

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