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Record and Replay vSphere Inventory using govc and vcsim 

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Happy New Year! 🥳

I wanted kick off 2021 with something I had just learned about right at the end of 2020 which I think this will be useful going into the new year for a number of different use cases. Back in 2017, I wrote about a new and lighter weight version of the vCenter Simulator (vcsim) which had been developed as part of the govmomi (vSphere SDK for Go) project. Since then, the govmomi project has grown exponentially and is now integral to a number of popular open source projects such as Packer builder for vSphere, Terraform provider for vSphere and Kubernetes Cluster API for vSphere (CAPV) to just name a few.

Govmomi is also heavily used internally by VMware for both development and testing purposes. In fact, it has been used to build a number of new VMware features such as the vSphere Integrated Containers (VIC) solution and most recently the vSphere with Tanzu capability that was introduced in vSphere 7.0.

Getting back to vcsim, this has been an invaluable tool for both our VMware developers but also the general VMware community. The ability to "simulate" a mocked vSphere environment with a basic inventory can be extremely useful for learning about the vSphere API and interacting with this endpoint using any vSphere SDK including PowerCLI. For automation folks, this can be useful for designing and creating your scripts in an offline mode before testing it against a real environment. For folks building 3rd party solutions that includes a visual interface, this is an easy way to test out your UI and ensure that there are no issues for large vSphere inventories which can be difficult to validate in a development environment.

Simulating a fake vSphere inventory is great, but it also has its limitations. There are so many unrealized use cases if you could capture a real vSphere inventory and then replay that back using vcsim. Just think about a bug reproduction use case and being able to share a real vSphere inventory with a development or QA team without needing to provide them direct access to the production environment?

In my opinion, this was the missing key feature from the original vcsim. To my surprise, this functionality was actually added to govc/vcsim earlier last year and I was quite happy with its implementation! Let's now take a closer look at how the record and replay functionality of govc/vcsim works.

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govcsim - Neat incubation project (vCenter Server & ESXi API based simulator)

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I know many of my readers have inquired about VCSIM (vCenter Server Simulator) which was a really useful tool that served a variety of use cases, but unfortunately it had stopped working with the VCSA 6.0 release. VCSIM is another topic that is near and dear to me and it is something I continue to push and advocate for internally at VMware. Earlier this week, I came to learn about a cool new incubation project that Doug MacEachern had been working on for some time now. Doug is an awesome VMware developer working on the vSphere Integrated Containers (vIC) project and he is also well known for his active contributions to both govmomi (vSphere SDK for Go) and govc CLI.

As you can probably guess from the title, the name of the project is called govcsim and it is a vCenter Server and ESXi API based simulator written using govmomi. It creates a vCenter Server model with a datacenter, hosts, cluster, resource pools, networks and a datastore. The naming of the objects is similar to that of the original VCSIM mode that was included with the VCSA. The number of resources can be increased or decreased using the various resource type flags. Resources can also be created and removed using the API. Doug had developed the tool to provide an easy way for their team to test some of the work they are doing with vIC. The tool is still under incubation but continues to received enhancements. In fact, the other day when I had used it for the first time, I had found a couple of issues which Doug resolved immediately.

I got a chance to give govcsim a spin the other day and currently you can connect to it using govmomi, govc, pyvomi (vSphere SDK for Python) or rbvmomi (vSphere SDK for Ruby). It currently does not work with PowerCLI (connects but no inventory), I know this is something Doug is currently looking into. You might also be able to connect using other vSphere SDKs but these are the ones that Doug and I have tried so far.

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Slick way of deploying OVF/OVA directly to ESXi & vCenter Server using govc CLI

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I have been meaning to write about this neat little feature that was added to the govc CLI late last year that allows you to easily deploy any OVF/OVA without the need of ovftool. You might ask, why not use ovftool? Well, if you just need to perform a very basic OVF/OVA deploy and prefer not to install anything on your desktop, this can be a nice alternative. govc is provided as a simple binary that is platform agnostic and supports Windows, Linux & Mac OS X. govc is built using govmomi which is also known as the vSphere SDK for Go and this also means you can consume this capablitity beyond just the CLI but also programmatically if you wish. Obviously, the CLI is the easiest method which I will demonstrate below.

Just to be clear, there is still a huge amount of value in using ovftool as it contains a large mount of functionality that is not found any where else. It is still the recommended tool for deploying OVF/OVA across all VMware based Hypervisors and is extensively used by other VMware's products for general OVF/OVA deployment.

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