title: Run scripts in guest OS with vRA ABX Actions
---
Thus far in my [vRealize Automation project](series/vra8), I've primarily been handing the payload over to vRealize Orchestrator to do the heavy lifting on the back end. This approach works really well for complex multi-part workflows (like when [generating unique hostnames](vra8-custom-provisioning-part-two#the-vro-workflow)), but it may be overkill for more linear tasks (such as just running some simple commands inside of a deployed guest OS). In this post, I'll explore how I use [vRA Action Based eXtensibility (ABX)](https://blogs.vmware.com/management/2020/09/vra-abx-flow.html) to do just that.
### The Goal
My ABX action is going to use PowerCLI to perform a few steps inside a deployed guest OS (Windows-only for this demonstration):
1. Auto-update VM tools (if needed).
2. Add specified domain users/groups to the local Administrators group.
3. Extend the C: volume to fill the VMDK.
4. Set up Windows Firewall to enable remote access.
5. Create a scheduled task to attempt to automatically apply any available Windows updates.
### Template Changes
#### Cloud Assembly
I'll need to start by updating the cloud template so that the requester can input an (optional) list of admin accounts to be added to the VM, and to enable specifying a disk size to override the default from the source VM template.
I will also add some properties to tell PowerCLI (and the `Invoke-VmScript` cmdlet in particular) how to connect to the VM.
##### Inputs section
I'll kick this off by going into Cloud Assembly and editing the `WindowsDemo` template I've been working on for the past few eons. I'll add a `diskSize` input:
```yaml
formatVersion: 1
inputs:
site: [...]
image: [...]
size: [...]
diskSize:
title: 'System drive size'
default: 60
type: integer
minimum: 60
maximum: 200
network: [...]
adJoin: [...]
[...]
```
The default value is set to 60GB to match the VMDK attached to the source template; that's also the minimum value since shrinking disks gets messy.
I'll also drop in an `adminsList` input at the bottom of the section:
```yaml
[...]
poc_email: [...]
ticket: [...]
adminsList:
type: string
title: Administrators
description: Comma-separated list of domain accounts/groups which need admin access to this server.
default: ''
resources:
Cloud_vSphere_Machine_1:
[...]
```
##### Resources section
In the Resources section of the cloud template, I'm going to add a few properties that will tell the ABX script how to connect to the appropriate vCenter and then the VM.
-`vCenter`: The vCenter server where the VM will be deployed, and thus the server which PowerCLI will authenticate against. In this case, I've only got one vCenter, but a larger environment might have multiples. Defining this in the cloud template makes it easy to select automagically if needed. (For instance, if I had a `bow-vcsa` and a `dre-vcsa` for my different sites, I could do something like `vCenter: '${input.site}-vcsa.lab.bowdre.net'` here.)
-`vCenterUser`: The username with rights to the VM in vCenter. Again, this doesn't have to be a static assignment.
-`templateUser`: This is the account that will be used by `Invoke-VmScript` to log in to the guest OS. My template will use the default `Administrator` account for non-domain systems, but the `lab\vra` service account on domain-joined systems (using the `adJoin` input I [set up earlier](joining-vms-to-active-directory-in-site-specific-ous-with-vra8#cloud-template)).
I'll also include the `adminsList` input from earlier so that can get passed to ABX as well. And I'm going to add in an `adJoin` property (mapped to the [existing `input.adJoin`](joining-vms-to-active-directory-in-site-specific-ous-with-vra8#cloud-template)) so that I'll have that to work with later.
I now need to also make some updates to the custom form configuration in Service Broker so that the new fields will appear on the request form. First things first, though: after switching to the Service Broker UI, I go to **Content & Policies > Content Sources**, open the linked content source, and click the **Save & Import** button to force Service Broker to pull in the latest versions from Cloud Assembly.
I can then go to **Content**, click the three-dot menu next to my `WindowsDemo` item, and select the **Customize Form** option. I drag-and-drop the `System drive size` from the *Schema Elements* section onto the canvas, placing it directly below the existing `Resource Size` field.
On the **Values** tab, I change the *Step* option to `5` so that we won't wind up with users requesting a disk size of `62.357 GB` or anything crazy like that.
That should be everything I need to add to the custom form so I'll be sure to hit that big **Save** button before moving on.
### Extensibility
Okay, now it's time to actually make the stuff work on the back end. But before I get to writing the actual script, there's something else I'll need to do first. Remember how I added properties to store the usernames for vCenter and the VM template in the cloud template? My ABX action will also need to know the passwords for those accounts. I didn't add those to the cloud template since anything added as a property there (even if flagged as a secret!) would be visible in plain text to any external handlers (like vRO). Instead, I'll store those passwords as encrypted Action Constants.
#### Action Constants
From the vRA Cloud Assembly interface, I'll navigate to **Extensibility > Library > Actions** and then click the **Action Constants** button up top. I can then click **New Action Constant** and start creating the ones I need:
-`vCenterPassword`: for logging into vCenter.
-`templatePassWinWorkgroup`: for logging into non-domain VMs.
-`templatePassWinDomain`: for logging into VMs with the designated domain credentials.
I'll make sure to enable the *Encrypt the action constant value* toggle for each so they'll be protected.
I like to think that it's fairly well documented (but I've also been staring at / tweaking this for a while); here's the gist of what it's doing:
1. Capture vCenter login credentials from the Action Constants and the `customProperties` of the deployment (from the cloud template).
2. Use those creds to `Connect-ViServer` to the vCenter instance.
3. Find the VM object which matches the `resourceName` from the vRA deployment.
4. Wait for VM tools to be running and accessible on that VM.
5. Determine the OS type of the VM (Windows/Linux).
6. If it's Windows and the tools are out of date, update them and wait for the reboot to complete.
7. If it's Windows, move on:
8. If it needs to add accounts to the Administrators group, assemble the needed script and run it in the guest via `Invoke-VmScript`.
9. Assemble a script to expand the C: volume to fill whatever size VMDK is attached as HDD1, and run it in the guest via `Invoke-VmScript`.
10. Assemble a script to set common firewall exceptions for remote access, and run it in the guest via `Invoke-VmScript`.
11. Assemble a script to schedule a task to (attempt to) apply Windows updates, and run it in the guest via `Invoke-VmScript`.
It wouldn't be hard to customize the script to perform different actions (or even run against Linux systems - just set `$whateverScript = "apt update && apt upgrade"` (or whatever) and call it with `$runWhateverScript = Invoke-VMScript -VM $vm -ScriptText $whateverScript -GuestUser $templateUser -GuestPassword $templatePassword`), but this is as far as I'm going to take it for this demo.
#### Event subscription
Before I can test the new action, I'll need to first add an extensibility subscription so that the ABX action will get called during the deployment. So I head to **Extensibility > Subscriptions** and click the **New Subscription** button.
I'll be using this to call my new `configureGuest` action - so I'll name the subscription `Configure Guest`. I tie it to the `Compute Post Provision` event, and bind my action:
I do have another subsciption on that event already, [`VM Post-Provisioning`](adding-vm-notes-and-custom-attributes-with-vra8#extensibility-subscription) which is used to modify the VM object with notes and custom attributes. I'd like to make sure that my work inside the guest happens after that other subscription is completed, so I'll enable blocking and give it a priority of `2`:
After hitting the **Save** button, I go back to that other `VM Post-Provisioning` subscription, set it to enable blocking, and give it a priority of `1`:
Note that I've set the disk size to 65GB (up from the default of 60), and I'm adding `lab\testy` as a local admin on the deployed system.
Once the deployment finishes, I can switch back to Cloud Assembly and check **Extensibility > Activity > Action Runs** and then click on the `configureGuest` run to see how it did.
So it *claims* to have successfully updated the VM tools, added `lab\testy` to the local `Administrators` group, extended the `C:` volume to fill the 65GB virtual disk, added firewall rules to permit remote access, and created a scheduled task to apply updates. I can open a console session to the VM to spot-check the results.
This is really just the start of what I've been able to do in-guest leveraging `Invoke-VmScript` from an ABX action. I've got a [slightly-larger version of this script](https://github.com/jbowdre/misc-scripts/blob/main/vRealize/configure_guest.ps1) which also performs similar actions in Linux guests as well. And I've also cobbled together ABX solutions for generating randomized passwords for local accounts and storing them in an organization's password management solution. I would like to get around to documenting those here in the future... we'll see.
In any case, hopefully this information might help someone else to get started down this path. I'd love to see whatever enhancements you are able to come up with!
