ESXi – Page 97

Remotely query an ESXi host without adding it to vCenter Server

07.19.2016 by William Lam // 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.

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.

How to automate vSphere MOB operations using PowerShell?

07.13.2016 by William Lam // 8 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