Using ESXi ISO image builder with VMware vSphere 7.0 Update 2

Creating custom ESXi images is useful when you need to add custom drivers to your installation ESXi ISO. Previously, there were third-party tools that are no longer maintained. However, since vSphere 6.x, VMware has offered its own utility, which is built into vSphere, called ESXi Image Builder.

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Vladan Seget

Vladan Seget is an independent consultant, professional blogger, vExpert 2009-2021, VCAP-DCA/DCD and MCSA. He has been working for over 20 years as a system engineer.

How to Add ESXi Software Depot

To work with software depots and customize image profiles, you'll have to add one or more software depots to the ESXi Image Builder Inventory.

There are two possibilities:

Offline depot—You can use an offline file (ZIP)
Online depot—Directly via a URL pointing to the VMware official software depots

Let's first try to do an online depot. Click New > Add Software Depot, and then enter a Name and the VMware online depot URL. Alternatively, you can add a local file, which you can download from VMware.

The second possibility is useful for environments that do not have internet access. The URL is https://hostupdate.vmware.com/software/VUM/PRODUCTION/main/vmw-depot-index.xml

Add VMware ESXi Software Depot

Within each depot, you'll see the images and its vSphere Installation Bundles (VIBs). A VIB is an ESXi software package. VMware and its partners package solutions, drivers, CIM providers, and applications that extend the ESXi platform as VIBs. You can use VIBs to create and customize ISO images or to upgrade ESXi hosts by installing VIBs asynchronously onto the hosts.

What is the VMware Offline Depot? VMware also calls it an offline bundle. It is a ZIP file that you download from the internet or copy from some media. You can save the zip file on a local or shared network drive. Offline bundles are also available on the websites of third-party vendors.

Since the release of vSphere 7.0, VMware has distributed an add-on .zip file that contains the delta between the OEM custom image and the base image that VMware provides. So, you can download the original VMware ESXi image and custom ISO images, as well as those OEM add-ons.

VMware OEM Add Ons

Create a personalized ESXi ISO image

We'll create an offline depot and then import the ZIP file we have downloaded from VMware. We're using the latest VMware-ESXi-7.0U2a-17867351-depot.zip file (offline bundle), available in the MyVMware account.

First, create a software depot as a "custom depot" (this is the same as in the first screenshot, but choose the bottom radio button). Just give it a meaningful name and click OK.

Add an offline depot

Then import the driver you want to include in the final ISO. In my case, I chose an NIC driver not present on the original ISO.

Add an offline depot

Now, create another new depot where we'll import the latest original ESXi 7 ZIP file.

Create another software depot for the original ESXi image

Import the ZIP file inside this depot by clicking the Import button, as shown in the image below. Repeat the steps for each depot.

Import the latest original ESXi 7 ZIP file

You will see two image profiles. There is the standard, which includes VMware Tools, and the no-tools, which does not include VMware Tools. The latter is usually used for auto deploying stateless environments, which allow the image to be more lightweight and faster to boot.

Now that we have both depots, the easiest way is to create a clone of the original image and add the new drivers to it during the process.

Just select the image profile you want to use, and click the Clone button.

Select the desired image profile and clone it

A new assistant starts, which allows you to specify a name for the new image profile. In the image below, the arrow points out the selection of the original depot that we're making the clone from.

Clone of ESXi 7.0.2a standard

Then, check the box next to your driver so it can be included in the final image. If you have multiple depots, be sure to select only the drivers you want to include in the final image.

Check the box to select your driver to be included in the image

Then, finish the wizard to complete the process.

Finish the wizard

Now, we can export the image profile. Note that we have selected the "Vladan_ESXi" custom image that we just created. You can specify whether you want to include the installer in the ISO.

You can also skip acceptance level checking, as during the export, there is a VIB Validation. This process is fairly important because all dependencies are checked and validated.

When you export an image profile to an ISO, vSphere ESXi Image Builder validates each VIB, so the system has a lot to do. It performs the following actions:

Conflict Checks—Image Builder validates that there are no conflicts by checking the Conflicts property of each SoftwarePackage.
Signature Validation—The system performs a VIB signature validation, which prevents unauthorized modification of VIB packages. The signature is a cryptographic checksum that guarantees that a VIB was produced by the author.
File Path Rules—The system verifies that VIBs follow file path usage rules. VMware tests VMwareCertified and VMwareAccepted VIBs to guarantee that those VIBs always follow file path usage rules.

You can also generate a zip archive.

Export your image

The Export button changes to a Download button. Just click it to download your final ISO file where your driver is installed. You can use this ISO as an installation media.

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Download your final ISO file

Final words

This was a small tutorial to teach us how to use the vSphere 7 Image Builder tool, which works hand-in-hand with Auto Deploy. But if you don't use Auto Deploy in your organization, then you can use it only as an Image Builder and export your customized ESXi images as ISO files.