WilliamLam.com

Remotely query an ESXi host without adding it to vCenter Server

by // Leave a Comment

I was browsing through the vSphere API Reference the other day and I came across an interesting vSphere API called QueryConnectionInfoViaSpec() which was introduced in vSphere 6.0. This new API is similiar to the existing QueryConnectionInfo() method which also allows you to remotely query an ESXi host without requiring you to add it to your vCenter Server Inventory, which I did not know about before. Some of the information that you can retrieve is whether it is currently being managed by an existing vCenter Server and if so, what is its IP Address, any registered Virtual Machines, networks and datastores that may be configured along with underlying host capabilities.

The main difference between this new API is that instead of accepting a list of arguments to the method, it accepts a HostConnectSpec. It is a minor difference, but what this allows you to do is to be able to re-use that exact same spec in the AddHost_Task() API if you determine that you would like to add the ESXi host to your vCenter Server Inventory after inspecting the remote ESXi host. I think this is a useful API if you want to validate that you are not stealing an ESXi host from another managed vCenter Server and if you are, at least you know which vCenter Server it was being managed by. To demonstrate this vSphere API, I have created a simple PowerCLI script called Get-RemoteESXi.ps1 which requires a vCenter Server login as well as the Hostname/IP Address and credentials of the remote ESXi host you wish to query.

Here is an example output of running the script which stores the returned output to the $results variable.

query-remote-esxi-without-adding-to-vcenter-server
If you want to check whether the ESXi host is being managed by an existing vCenter Server, you can check the following property which will hold the IP Address of the vCenter Server if it is currently being managed:

$result.Host.ManagementServerIp

If you want to check if there are running VMs already on the ESXi host, you can check the following property:

$result.vm

As mentioned earlier, there is a ton of other information returned from the remote ESXi host and I will leave it as an exercise for the reader to explore further.

Quick Tip - Minor changes on how to customize vSphere 6.0 Update 2 Web Client login UI

by // 6 Comments

For those of you interested in customizing the vSphere Web Client login UI in the latest vSphere 6.0 Update 2 release, you may have found that after following the instructions here, the result is an empty background image. The reason this happens is that as of vSphere 6.0 Update 2, new capabilities such as a Logon Banner and 2-Factor Authentication using Smart Card support have been added. All of these capabilities are UI driven and as one would expect, they have updated HTML/CSS pages which from vSphere 6.0 or vSphere 6.0 Update 1. If you simply took the existing sample templates in my Github repo and replaced it on your system, the vSphere Web Client would not be able render them properly.

customize-vsphere-web-client-login-ui-vsphere-60-update-2
The fix is actually quite simple, instead of just copying the sample templates I have, you need to make a copy of the existing vSphere 6.0 Update 2 files (login.css & unpentry.jsp) and make the relevant code changes. Given the number questions I have received on this topic, I figure I would just create a new Github repo that contains vSphere 6.0 Update 2 specific sample themes.

Disclaimer: This is not officially supported by VMware, if you decide to enable this, please use at your own risk and ensure you backup all original files in case you need revert back to the original configurations.

For the full instructions and sample themes for customizing the vSphere Web Client login UI for vSphere 6.0 Update 2, have a look at the new Github repo here https://github.com/lamw/customize-vsphere-web-client-6.0u2 and for vSphere 6.5, have a look at the repo here https://github.com/lamw/customize-vsphere-web-client-6.5 

How to automate vSphere MOB operations using PowerShell?

by // 5 Comments

A couple of weeks back I was investigating something that involved the use of the vSphere Managed Object Browser (MOB) and I needed to automate a particular operation. For those of you not familiar with the vSphere MOB, it is a UI debugging tool that allows you to visualize and invoke vSphere APIs using just a web browser. The vSphere MOB is available on both vCenter Server and ESXi and uses the underlying vSphere API. Outside of learning about the vSphere APIs and potentially for troubleshooting purposes, there really is no good reason to be directly interacting with the vSphere MOB on a regular basis. Customers can use any one of the many vSphere SDK/CLIs to easily automate and interact with the vSphere API.

Having said that, there may be cases where you might want to invoke a specific operation using the vSphere MOB, such as private API for example. Obviously, using any private/internal APIs is not officially supported by VMware and their use will be at your own risk. Nonetheless, I had a specific operation that I needed to call from the vSphere MOB and wanted to do so using PowerShell. Several years back I had demonstrated how you could invoke the vSphere MOB using Python but I could not find any PowerShell examples that actually worked. I figured this would be a good learning opportunity for myself and probably something I or others could benefit in the future.

To provide a concrete example, I will be invoking a supported vSphere API called the QueryOptions which is used for accessing either a vCenter Server or ESXi Advanced Settings. For our example, I will be connecting to the vCenter Server's MOB and will be querying for a specific vCenter Server Advanced Setting. If we were to do this manually in the vSphere MOB, we would first open a web browser and login to the following URL: https://[VC-SERVER]/mob/?moid=VpxSettings&method=queryView

automate-vsphere-mob-using-powercli
If you wanted to see all advanced settings, you would leave the "name" parameter blank. For our example, we will query for the VirtualCenter.InstanceName property as shown in the screenshot above and then click on the "Invoke Method" to execute the vSphere API operation. If successful, it should display the results which in our case is the IP Address of my vCenter Server. Pretty straight forward vSphere MOB example. OK, onto automating this from PowerShell. I have created a sample PowerShell script called automate-vsphere-mob.ps1 which you will need to edit and provide your vCenter Server Hostname/IP Address and the vCenter Server credentials (can be read-only) since we are not performing any write operations.

Here are some more specific details on what is happening in the script for those interested:

  1. Authenticate to the vSphere MOB URL that you wish to invoke using an HTTP GET operation and storing the session into a variable named vmware (Line 28-29)
  2. Extract the hidden vmware-session-nonce property used to prevent Cross-Site Request Forgery (CSRF) (Line 31-40)
  3. Create the body request which must include the vmware-session-nounce property along with the vSphere API payload (Line 42-45)
  4. Invoke the actual vSphere API call using an HTTP POST along with the existing session from Step 1 and body payload
  5. Process the results (this will be specific to API call) and profit! (Line 50-59)

If you now run the script, you will see that the result is exactly what we saw from interactively using the vSphere MOB. Hopefully this will be useful for anyone who may have a need to automate against the vSphere MOB. For those curious on what I was investigating with the vSphere MOB, stay tuned for more details 🙂