govmomi (vSphere SDK for Go), govc CLI & Kubernetes on vSphere

One of the exciting announcements that was made last week at VMworld was the joint partnership between Docker, Google, Pivotal and VMware. Paul Strong (Office of the CTO) wrote a great blog post Better Together – Containers are a Natural Part of the Software-Defined Data Center where he goes into more details about the partnership. The really neat part of the announcement which I think some people may have missed is that this was more than just an announcement. There are actually active projects currently being worked on, most notably a working prototype for a Kubernetes vSphere Provider.

For those of you who are not familiar with Kubernetes, it is an open-source project that was started by Google which provides Container Cluster Management. You can think of Kubernetes as a placement engine/scheduler for Containers, similar to how vSphere DRS is responsible for scheduling Virtual Machines. The Kubernetes vSphere Provider allows you to run a Kubernetes Cluster on top of a vSphere based infrastructure and provides a platform for scheduling Docker Containers running on top of vSphere.

Kubernetes is completely written in Go (short for Golang), a programming language developed by Google. To be able to easily integrate with Kubernetes, a Go library needed to be written for the vSphere API and hence govmomi was born! Similar to pyvmomi and rbvmomi which are vSphere SDKs for Python and Ruby respectively, govomimi is the vSphere SDK equivalent for Go. The govmomi project is an open source project lead by VMware and you can find the Github repository at https://github.com/vmware/govmomi.

In addition to govmomi, I also learned about a neat little CLI that was built on top of the SDK called govc (currently an Alpha release) which provides a simplified command-line interface to a vSphere environment leveraging govmomi. You can find the source code under the govmomi Github repository https://github.com/vmware/govmomi/tree/master/govc. The Kubernetes vSphere Providers leverages govc to be able to orchestrate the deployment of a Kubernetes Cluster on top of vSphere leveraging the vSphere API.

To use govc, you will need to ensure you have Go 1.2+ installed on your system. Here are the steps on installing Go and govc

Step 1 - Download the latest Go package installer for your OS here and once you have Go installed, you can verify that everything is working by running the following command:

go version

Step 2 - Setup your build environment by running the following commands:

export GOPATH=$HOME/src/go
mkdir -p $GOPATH
export PATH=$PATH:$GOPATH/bin

Step 3 - Check out govc source code by running the following command:

go get github.com/vmware/govmomi/govc

At this point, govc has been installed. You can now connect to either a vCenter Server or ESXi host. The easiest way is to specify the vSphere API endpoint and credentials is by setting a couple of environmental variables, so you do not have to specify it on the command-line.

Step 4 - Run the following command and specify the username, password and either the hostname or IP Address of your vCenter Server or ESXi host:

export GOVC_URL='https://[USERNAME]:[PASSWORD]@[ESXI-OR-VCENTER-HOSTNAME-OR-IP]/sdk'

Step 5 - To verify that everything is working, you can run the following command to query the endpoint you have connected to:

govc about

If everything was successful, you should see some basic information about the vSphere API endpoint you have connected to. In the example above, I am connected to a VCSA (vCenter Server Appliance). The govc CLI is quite similar to RVC with commands broken up into various namespaces. However, one feature that is not there today is the ability to tab complete the commands which is something I just love about RVC!

You can also just run "govc" and it will provide a list of available commands:

You can get more details about each command by specifying --help command, here is an example of the host.info

To get information about one of my ESXi hosts, I need to specify --host.ip option along with the IP:

As you can see from the screenshot above, some basic information is displayed about my ESXi host which is running on a Mac Mini. If you would like to learn more about govc, I highly recommend you check out the govc repository on Github which has additional documentation. You can also file any bugs or feature requests you would like to see on the project page.

At this point you are now ready to proceed to the next steps which is to setup Kuberentes and deploy a Kubernetes Cluster onto your vSphere environment. Unfortunately I ran into a problem while going through the Kubernetes deployment and I did not know where to go next and decided to file a Github issue here. To my surprise, I immediately got a response back from the VMware Engineers who are working on the project. I had a couple of email exchanges with the team to debug the problem. It looks like we found the culprit and I was able to get Kubernetes up and running. There are a couple of minor caveats which I will explain in more detail in Part 2 of this post and walk you through the steps of deploying a Kubernetes Cluster running on top of vSphere.