ESXi – Page 91

How to automate vSphere MOB operations using PowerShell?

07.13.2016 by William Lam // 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

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:

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)
Extract the hidden vmware-session-nonce property used to prevent Cross-Site Request Forgery (CSRF) (Line 31-40)
Create the body request which must include the vmware-session-nounce property along with the vSphere API payload (Line 42-45)
Invoke the actual vSphere API call using an HTTP POST along with the existing session from Step 1 and body payload
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 🙂

Using the vSphere API to remotely collect ESXi configuration file (esx.conf)

06.23.2016 by William Lam // 9 Comments

Last week we took a look at two new Automated solutions here and here that allows us to leverage vCenter Server and the vSphere APIs to remotely extract information that historically required logging in directly into an ESXi host. While working on the two scripts, I was reminded of another use that could also be really useful which builds on top of some information that I had shared back in 2012. ESXi provides a very basic file manipulation capability that is exposed as a simple HTTPS-based interface.

Here is a quick recap of the three URLs which can be accessed by opening a browser and logging into the ESXi host:

https://esxi-1.primp-industries.com/host
https://esxi-1.primp-industries.com/folder
https://esxi-1.primp-industries.com/tmp

For the purpose of this article, we will be focusing on the first url endpoint /host and below is an example screenshot on some of the configuration files (46 in total) that you would be able to access using this interface.

One of the available ESXi configuration files that you access is the esx.conf file directly where it might be useful to periodically capture the state of this file for either auditing or troubleshooting purposes.

Note: Although esx.conf does contain some amount of the ESXi configurations, it does not represent the full state of the ESXi host. If you wish to perform periodic full backups of your ESXi host (which includes esx.conf by default among other files), there is a vSphere API for this by using the HostFirmwareSystem and the BackupFirmwareConfiguration() method.

Applying the same technique as I have described here, we can easily retrieve the esx.conf for a specific ESXi host being managed by vCenter Server without needing directly login to the ESXi host or worse connecting via SSH. I have created a PowerCLI script called Get-Esxconf.ps1 which just accepts a VMHost object.

Here is an example of how you would use the function and screenshot below of the output:

$esxConf = Get-VMHost -Name "esxi-1" | Get-Esxconf

If you are interested in a specific key within the esx.conf configuration file, we further process the output. The following snippet below searches for the following key /system/uuid and will return the value as it iterates through the esx.conf output.

$esxConf = Get-VMHost -Name "esxi-1" | Get-Esxconf

$keyToSearchFor = "/system/uuid"

foreach ($line in $esxConf.Split("`n")) {
    $data = $line.split("=").trim().replace('"',"")
    if($data[0] -eq $keyToSearchFor) {
        Write-Host "Key:" $keyToSearchFor 
        write-Host "Value:" $data[1]
    }
}

Hopefully this gave you an idea of just one of the many use cases that can now be enabled through the use of the vSphere API and this ESXi interface. Here are just a few other use cases that I can think of on the top of my mind that could come in handy:

Managing ESXi SSH public/private keys, we have mostly been using httpGet, but you can also use an httpPut to upload these files without needing to go to each and every ESXi host
Replacing Custom SSL Certificates if you are not using VMCA, you can also use an httpPut request to upload these files (you will need to restart hostd or reboot the host for the new SSL Certificates to go into effect)
Quickly access the vpxa.cfg (vCenter Server agent) configuration file for troubleshooting purposes

Using the vSphere API to remotely collect ESXi esxcfg-info

06.15.2016 by William Lam // 7 Comments

Using the same technique as I have described here, you can now also use the vSphere API to connect to vCenter Server to remotely collect esxcfg-info from ESXi hosts without having to SSH'ing to each and every single host. Historically, the esxcfg-* commands were only available in the classic ESX Service Console (COS) and the ESXi Shell. As part of the ESXi transition, VMware has converted all the commands over to the vSphere API which means that you no longer needed to run those local CLIs commands to manage or configure your ESXi hosts like you used to with classic ESX.

The only exception that still exists today is the esxcfg-info command, which still contains a lot of useful information, for some of which is not currently in the vSphere API today. Similiar to the vm-support.cgi script, there is also an esxcfg-info.cgi script which I had blogged about here back in 2011. To output the esxcfg-info, simply open a web browser and specify the following URL with the Hostname/IP Address of your ESXi host:

https://esxi-1.primp-industries.com/cgi-bin/esxcfg-info.cgi

Once you have authenticated with a valid user, you will see that the output matches the output if you were to manually run esxcfg-info command on the ESXi Shell.

Instead of the raw output that you are all probably familiar with, you can also format the output using XML simply by appending ?xml to the end of the URL:

https://esxi-1.primp-industries.com/cgi-bin/esxcfg-info.cgi?xml

With the second formatted option, we can now easily retrieve the result and store that into an XML object for processing using any one of our favorite scripting/programming languages. In the previous article, I demonstrated the use of the vSphere API method AcquireGenericServiceTicket() using a pyvmomi (vSphere SDK for Python) script. In this example, I will demonstrate the exact same use of the vSphere API but now leveraging PowerCLI. I have created a script called Get-Esxcfginfo.ps1 which connects to a vCenter Server and requests a session ticket to a specific ESXi host's esxcfg-info.cgi URL and that will then return us a one time HTTP request to connect to the ESXi host to retrieve the requested information.

Here is an example on how to use the command which will return the XML output which would then require further processing of the XML:

$xmlResult = Get-VMHost -Name "192.168.1.190" | Get-Esxcfginfo

I have also included an example of how to parse the XML return in the script itself. As you can see from the screenshot below, I am extracting the Device Name, Vendor Name & Vendor ID from the esxcfg-info output.

Pretty cool huh? Stay tuned for one more blog post which I will show you another way in which you can make use of this vSphere API!