Backing Up Portgroup Data with PowerShell and XML

Managing virtual standard switches (vSwitches) in a VMware environment, large or small, can cause a lot of headaches. Ensuring each portgroup is named the same, has the same VLAN and is present on each host can be a challenge. Virtual distributed switches (dvSwitches) exist to make our lives easier, but aren’t always available due to licensing or other restrictions. They have their own drawbacks, but the good generally outweighs the bad.

As I have been spending a significant amount of time in PowerShell and XML recently I wrote a script designed to backup the Portgroup configuration of all your clusters to ensure that all hosts will have the proper networking configuration during host rebuilds or additions. Let’s walk through this script and show you all the different elements.

1. Here we define and connect to the vCenter server

$vCenterFqdn = "vcenter01.domain.local"
Connect-viserver $vCenterFqdn

2. Here we are defining the path for our Portgroups.xml file. We’ll reference this variable later on.

$xmlNetworkPath="C:\Scripts\XML\Portgroups.xml"

3. Here we are checking to see if this file already exists. If it does we’ll skip ahead to the population side, but if not we’ll have to create it. $networkCheck tests the path defined in the variable $xmlNetworkPath. If that file is there, we’re writing into the console that it exists and we’re moving on. If it doesn’t exist we move on to step 4.

$networkCheck = Test-Path $xmlNetworkPath
IF ($networkCheck -eq $True){Write-Host "Portgroup file already exists. Continuing..." -foreground "Green"}
ELSE
{Write-Host "Portgroup file not created. Creating..." -foreground "Yellow"}

4. Since this is our first run, this file doesn’t exist yet so we need to create it. Populating an empty XML file is not something I ever figured out how to do. Someone much smarter than me in XML and PowerShell can figure it out, but I found a nice work around by creating an XML template. This is an outline of what our XML file will be and we’re just filling in the data as we go.

$xmlNetwork=[xml]@’ is saying everything between @’ and ‘@ will be part of this file. At the end, we’re saving this output ($xmlNetwork.Save) to the file path we defined earlier ($xmlNetworkPath).


$xmlNetwork=[xml]@'

<vSwitchConfig>
  <templates>
    <Portgroup>
      <vlanId></vlanId>
      <virtualSwitch></virtualSwitch>
      <cluster></cluster>
    </Portgroup>
  </templates>
  <Portgroups>
    <test />
  </Portgroups>
</vSwitchConfig>
‘@
$xmlNetwork.Save($xmlNetworkPath)

5. In case we run into permissions issues we want to perform an additional check to ensure that file was actually written. For the most part we’re just repeating Step 3. The difference here is we’re changing the output in “Write-Host” but also if the file isn’t created, we need to kill the script. The message is written that the file was not created, then we wait 20 seconds, then exit the script. The reason we add the “Start-Sleep” is in case this script is run by just double-clicking and not triggered from within a powershell window, the script will exit and you’ll never know why.

$networkCheck = Test-Path $xmlNetworkPath
IF ($networkCheck -eq $True){Write-Host "Portgroup file created successfully. Continuing..." -foreground "Green"}
ELSE
{Write-Host "Portgroup file not created. Exiting..." -foreground "Red"; Start-Sleep 20; Break}}

6. Now we need to read the contents of that XML file we created in XML format. The [XML] denotes that this is an XML file. $xmlNetwork is just the variable name I chose (this can be anything you want) and $xmlNetworkPath is the path to the file we defined in step 2

[XML]$xmlNetwork = Get-Content $xmlNetworkPath

7. Now comes the fun part where we actually start pulling data from vCenter. We’re going to get all the clusters in the vCenter we’re connected to. The ForEach command says that for every cluster we need to run this same command. So in each cluster we’re looking for an ESXi host that is currently connected, then we choose a random host from the cluster (get-random) and on that random host we get all the virtual portgroups that aren’t on dvSwitches.

$getClusters = Get-Cluster
ForEach ($cluster in $getClusters) {
$getPortgroups = $cluster | Get-VMHost | Where {$_.ConnectionState -ne "NotResponding"} | Get-Random | Get-VirtualPortGroup | Where {$_.key -notlike "*dvportgroup*"}

8. Now that we have all these portgroups let’s get all the data we need in them. We perform another ForEach on every Portgroup that was on that host. The $testPg variable is used to see if the current Portgroup name ($pgName.Name) is present in the XML file. What we don’t want is to re-add the same Portgroup name over and over again, we just want a single reference to the portgroup name and we’ll add another entry for the clusters that contain it. $testPg -eq $null means if the portgroup name isn’t there, we’ll create a new entry.

foreach ($pgName in $getPortGroups) {
$testPg = $xmlNetwork.vSwitchConfig.Portgroups.Portgroup|Where {$_.name -eq $pgName.Name}
IF ($testPg -eq $null)

9. If the Portgroup isn’t there we need to create a new entry. Looking at the XML file outline we created in Step 4 you see the tag. This is used to work around my inability to create new entries in XML. We copy the section below and then fill out the data as we go


<Portgroup>
  <vlanId></vlanId>
  <virtualSwitch></virtualSwitch>
  <cluster></cluster>
</Portgroup>

The variable “$xmlNetwork” was defined in Step 6 and is the name of our XML file. The addition of “.vSwitchConfig” is the top level tag in our XML file from Step 4.
The variable “$parentNode” defines the top-level of the XML file we’ll be using from our template.
The variable “$destinationNode” defines where this copied data is going to be placed.
The variable “$cloneNode” defines what tag we’re copying from $parentNode.
The variable “$addNameAttribute” is creating an attribute called “name” and the name we’re giving it is the name of the portgroup we’re pulling from vCenter. Adding “.Value = ” to the end of this variable gives us the ability to define the name when we’re creating the new portgroup tag.
The variable $newNode is used to create the new Portgroup tag and then “.InnerXML =” allows us to chose the template tag from the XML file.
(The use of [void] is something I don’t fully grasp. This is the only way it works, but I can’t tell you why.)
Using $destinationNode.AppendChild is saying place this new tag into the $destinationNode location. $newNode is the data that’s being added. “.Attributes” allows us to assign the new name Attribute we defined and “.Append($addNameAttribute)” places that attribute tag.
The variable $updateNetwork is a lookup in the XML file to find a portgroup with the tag we just created.
Once we find that portgroup, $updateVLAN, $updateVirtualSwitch, and $updateCluster are used to assign the values to these empty tags that were created.


{
$parentNode = $xmlNetwork.vSwitchConfig.templates
$destinationNode = $xmlNetwork.vSwitchConfig.Portgroups
$cloneNode = $parentNode.SelectSingleNode("Portgroup")
$addNameAttribute = $xmlNetwork.CreateAttribute("name")
$addNameAttribute.Value = $pgName.Name
$newNode = $xmlNetwork.CreateElement("Portgroup")
$newNode.InnerXML = $cloneNode.InnerXML
[void]$destinationNode.AppendChild($newNode).Attributes.Append($addNameAttribute)
$updateNetwork = ($xmlNetwork.vSwitchConfig.Portgroups.Portgroup|Where {$_.name -eq $pgName.Name})
$updateVLAN = $updateNetwork.vlanId = $pgName.VLanId.ToString()
$updateVirtualSwitch = $updateNetwork.virtualSwitch = $pgName.VirtualSwitchName
$updateCluster = $updateNetwork.cluster = $cluster.Name
}

10. In the event this portgroup already exists, we have the ELSE portion of our IF statement we started in Step 8. Here we’re referencing the portgroup in question and checking to see if the cluster tag has already been added. We look up the portgroup name “$testPg” and search for a cluster that matches the cluster we’re currently working with. If that cluster doesn’t exist, we add a new element ($xmlNetwork.CreateElement(“cluster”)) and populate its value ($addCluster.InnerText = $cluster.Name)

If that cluster tag already exists for that Portgroup, we don’t do anything “{}”


ELSE {($testCluster = $testPg|Where {$_.cluster -eq $cluster.Name});
IF ($testCluster -eq $null) {
$addCluster = $xmlNetwork.CreateElement("cluster");
$addCluster.InnerText = $cluster.Name
$testPg.AppendChild($addCluster) | Out-Null }ELSE{}}
}}

11. Once all of our clusters and Portgroups have been looped through. We need to save that data to the XML file we created.

$xmlNetwork.Save($xmlNetworkPath)

12. Now that the file has been saved, we want to see what data has been written. This isn’t required, but just adds a nice little output to the screen so you can see that the data has been populated as expected.

We perform the same Get-Content command with our [XML] tag. Then we write the output of every portgroup, sorted by name, into a table so we can see all the data.


[XML]$xmlNetwork = Get-Content $xmlNetworkPath
Write-Host "The following Portgroup configuration exists in $($xmlNetworkPath)" -foreground "Yellow"
$xmlNetwork.vSwitchConfig.Portgroups.Portgroup | Sort name | Format-Table

I have obscured some of the networks and VLANs in use in my environment, but this is the output you can expect.

All together this is what the script looks like:


#Connect to the defined vCenter Server
$vCenterFqdn = "vcenter01.domain.local"
Connect-viserver $vCenterFqdn

#Define XML File Path
$xmlNetworkPath="C:\Scripts\XML\Portgroups.xml"

#Check for Portgroup XML File
$networkCheck = Test-Path $xmlNetworkPath
IF ($networkCheck -eq $True){Write-Host "Portgroup file already exists. Continuing..." -foreground "Green"}
ELSE
{Write-Host "Portgroup file not created. Creating..." -foreground "Yellow"

#Create XML Portgroup File

$xmlNetwork=[xml]@'

<vSwitchConfig>
  <templates>
    <Portgroup>
      <vlanId></vlanId>
      <virtualSwitch></virtualSwitch>
      <cluster></cluster>
    </Portgroup>
  </templates>
  <Portgroups>
    <test />
  </Portgroups>
</vSwitchConfig>
'@
$xmlNetwork.Save($xmlNetworkPath)

$networkCheck = Test-Path $xmlNetworkPath
IF ($networkCheck -eq $True){Write-Host “Portgroup file created successfully. Continuing…” -foreground “Green”}
ELSE
{Write-Host “Portgroup file not created. Exiting…” -foreground “Red”;Start-Sleep 20; BREAK}}

#Get contents of XML file
[XML]$xmlNetwork = Get-Content $xmlNetworkPath

#Gather all hosts in each cluster
$getClusters = Get-Cluster
foreach ($cluster in $getClusters) {
$getPortgroups = $cluster | Get-VMHost | Where {$_.ConnectionState -ne “NotResponding”} | Get-Random | Get-VirtualPortGroup | Where {$_.key -notlike “*dvportgroup*”}
foreach ($pgName in $getPortGroups) {
$testPg = $xmlNetwork.vSwitchConfig.Portgroups.Portgroup|Where {$_.name -eq $pgName.Name}
IF ($testPg -eq $null) {
$parentNode = $xmlNetwork.vSwitchConfig.templates
$destinationNode = $xmlNetwork.vSwitchConfig.Portgroups
$cloneNode = $parentNode.SelectSingleNode(“Portgroup”)
$addNameAttribute = $xmlNetwork.CreateAttribute(“name”)
$addNameAttribute.Value = $pgName.Name
$newNode = $xmlNetwork.CreateElement(“Portgroup”)
$newNode.InnerXML = $cloneNode.InnerXML
[void]$destinationNode.AppendChild($newNode).Attributes.Append($addNameAttribute)
$updateNetwork = ($xmlNetwork.vSwitchConfig.Portgroups.Portgroup|Where {$_.name -eq $pgName.Name})
$updateVLAN = $updateNetwork.vlanId = $pgName.VLanId.ToString()
$updateVirtualSwitch = $updateNetwork.virtualSwitch = $pgName.VirtualSwitchName
$updateCluster = $updateNetwork.cluster = $cluster.Name
} ELSE {($testCluster = $testPg|Where {$_.cluster -eq $cluster.Name});
IF ($testCluster -eq $null) {
$addCluster = $xmlNetwork.CreateElement(“cluster”);
$addCluster.InnerText = $cluster
$testPg.AppendChild($addCluster) | Out-Null }ELSE{}}
}}
$xmlNetwork.Save($xmlNetworkPath)

#Display Results
[XML]$xmlNetwork = Get-Content $xmlNetworkPath
Write-Host “The following Portgroup configuration exists in $($xmlNetworkPath)” -foreground “Yellow”
$xmlNetwork.vSwitchConfig.Portgroups.Portgroup | Sort name | Format-Table

Removing Values in XML Using PowerShell

We’ve gathered values from our XML file and we’ve managed to add values to an XML file using PowerShell, but what about deleting? What I’m talking about is deleting XML tags and attributes, not deleting the value in an existing tag. Let’s look at our sample file and I’ll explain.

Above is our sample.xml file that was updated in the last post. Inside we have individual portgroups with a name and elements that we were added. In the context of the project I was working on, I needed the ability to delete a portgroup and all of its elements (VLAN, virtual switch, and cluster), but in some situations I needed to just delete the cluster. If a portgroup needed to be removed from one specific cluster, but remaining available to another cluster I couldn’t have the entire portgroup removed as it could affect virtual machines that are still running.

How do we do it? Let’s find out.

Just like before, let’s get the contents of our XML file so we can work with the data.

$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

The two things we need in order to remove a portgroup are the name of the portgroup and the name of the cluster. Based on the sample.xml file, we see that “VM Network” is on two clusters (cluster1 and NestedCluster) so let’s start there. Let’s get some simple variables setup just like we did last time.

$name = Read-Host -Prompt "Enter the name of the Portgroup (ex: Management Network)"
$cluster = Read-Host -Prompt "Enter the name of the cluster for this Portgroup (ex: Cluster1)"

I’ve created a new powershell file called “removePortgroup.ps1” and it has the above variables in there prompting me to enter the name and the cluster of the portgroup to be removed.

Now that we have the XML contents and our variables defined it’s time to see what data is there. If you recall from my earlier post about getting data from XML, we can see the contents of our file by following the hierarchy. With the following command we can see all portgroups that have been defined.

$xmlConfig.config.portgroups.ChildNodes

Now that we know what’s there, we need to filter the results and only display the Web Network. We’ll pass this as a variable so we can use that info later.

$clusters = $xmlConfig.config.portgroups.ChildNodes | ? {$name -eq $_.name}

Using the same command as before but passing it as a variable, we added a parameter to search for the name of our Portgroup (VM Network) using the $name variable we created earlier and we are trying to match it with another portgroup of the same name. When we run the command “$clusters” we see what portgroup came back as a match. We can see the VM Network portgroup that has 2 clusters.

With this portgroup living on two clusters we are only interested in removing it from one which is NestedCluster. We’ll work on the logic for this later one, for now let’s focus on how you remove a single from this portgroup.

The following commands will remove the element that matches our $name and $cluster variables we created earlier.

$text = "#text"
$clusterTag = $xmlConfig.config.portgroups.portgroup | Where {$_.name -eq $name}
$updateTag = $clusterTag.SelectNodes("cluster") | Where {$_.$text -eq $cluster}
$updateTag.ParentNode.RemoveChild($updateTag)

We are looking for the Text inside of the tag. As you can see from the output at the bottom, it has a label (or whatever it is called) of #text. The problem is, when working within PowerShell, if I add a “#” to a line, it will comment out everything after it. We get around that limitation but creating a variable called $text and given it a value of #text. Maybe there is a better way of doing it, but this worked so I went with it.

The next line is looking for a portgroup matching $name. The next line is selecting the tag that matches $cluster. The final line is performing the removal of that tag. This still needs to be saved, so we’re not done yet, but at this point we have removed from . If you run the command below you can see that “NestedCluster” has been removed as a cluster in the “VM Network” portgroup.

$xmlConfig.config.portgroups.ChildNodes

Now what if this portgroup is only on one cluster and we want to delete it and all of its attributes completely? We can do so with the following command.

$xmlConfig.config.portgroups.ChildNodes | ? {$name -eq $_.name} | % {$xmlConfig.config.portgroups.RemoveChild($_)} | Out-Null

In this command, we are getting all the portgroups in the first part, then filtering the results where $name matches the name of an existing portgroup. Then we are removing that entire and all its contents from the XML file. The Out-Null is required to make it work, but I don’t really know why. Once again, this isn’t saved yet, we can do that in the next step.

In order to save we need to run the following command.

$xmlConfig.Save($xmlFile)

Now that this file is saved, we can re-check the XML file using the commands below

$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

If we run the command $xmlConfig.config.portgroups.childnodes we will see that “VM Network” is now gone

We can remove just an attribute or we can remove an entire element. How can we create a script to determine which one to use? If we wrap this all in an IF/ELSE statement we can do it pretty easily.

Using the $clusters variable we created earlier, we can perform a count of how many tags there are. Running the following command will show many clusters a portgroup is provisioned to.

$clusters.cluster.count

In our IF/ELSE statement, we are checking to see if the count is greater than 1 (-gt 1) and then performing the command to remove just the cluster tag. If it’s not greater than 1, we are running the command to remove the entire portgroup and all of its attributes.

$clusters = $xmlConfig.config.portgroups.ChildNodes | ? {$name -eq $_.name}
IF ($clusters.cluster.count -gt 1){
$text = "#text"
$clusterTag = $xmlConfig.config.portgroups.portgroup | Where {$_.name -eq $name}
$updateTag = $clusterTag.SelectNodes("cluster") | Where {$_.$text -eq $cluster}
$updateTag.ParentNode.RemoveChild($updateTag)
$xmlConfig.Save($xmlFile) } ELSE {
$xmlConfig.config.portgroups.ChildNodes | ? {$name -eq $_.name} | % {$xmlConfig.config.portgroups.RemoveChild($_)} | Out-Null
$xmlConfig.Save($xmlFile) }

Notice how we see the same #text and “NestedCluster” output after the commands ran when we were just trying to remove a cluster? That’s because powershell sees there are more than 1 cluster assigned to the VM Network portgroup and it just removed it.

Here is the full script to check if there are multiple XML attributes named “cluster” and remove it or remove the entire portgroup element.

#Define XML file and Get its contents
$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

#Define variables and prompt for input
$name = Read-Host -Prompt "Enter the name of the Portgroup (ex: Management Network)"
$cluster = Read-Host -Prompt "Enter the name of the cluster for this Portgroup (ex: Cluster1)"

#IF/ELSE Statement to remove a single attribute or an entire element
$clusters = $xmlConfig.config.portgroups.ChildNodes | ? {$name -eq $_.name}
IF ($clusters.cluster.count -gt 1){
$text = "#text"
$clusterTag = $xmlConfig.config.portgroups.portgroup | Where {$_.name -eq $name}
$updateTag = $clusterTag.SelectNodes("cluster") | Where {$_.$text -eq $cluster}
$updateTag.ParentNode.RemoveChild($updateTag)
$xmlConfig.Save($xmlFile) } ELSE {
$xmlConfig.config.portgroups.ChildNodes | ? {$name -eq $_.name} | % {$xmlConfig.config.portgroups.RemoveChild($_)} | Out-Null
$xmlConfig.Save($xmlFile) }

Adding Values to XML Using PowerShell

Continuing on from the previous post on getting values from an XML file using PowerShell, I’m going to talk about how to add values to an XML files. With the recent project I was working on I needed a way to easily add new portgroups into the XML configuration file. Every environment changes and while having something manually update an XML file would work there is always the possibility of messing up the syntax or something much worse.

Let’s have a look at the sample XML file again.

What we have here is 3 port groups (Management Network, VM Network, Web Network) with a VLAN, VirtualSwitch, and Cluster defined. The entire file sits inside the “config” tags. Each portgroup lives inside the “portgroups” tag, and the values for each portgroup live inside the individual “portgroup” tags.

The goal here is to add a brand new portgroup to this XML file so when we can then add that portgroup with the correct values to our ESXi hosts. Given our existing structure we’ll need a name, VLAN, Virtual Switch, and Cluster for this new portgroup.

In order to update our XML file we need to get the XML file contents and we do that by using the following command (again, using the file path as a variable so I can easily change it later).

$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

Now that we have the contents of the XML file, we need to gather the name, VLAN, Virtual Switch, and Cluster for this new portgroup. The question you’ll have to ask yourself is do you want to update the script file with each new portgroup you need to add or do you just want the script to prompt for those values each time it’s run?

If you want to manually update the file and let it run by itself just define the following variables in your script. For this example we’re creating a new portgroup called “App Network” with VLAN 31, on vSwitch1 and on cluster2.

$name = "App Network"
$vlanID = "31"
$virtualSwitch = "vSwitch1"
$cluster = "cluster2"

When we need to add these values into our XML file, we will refer to them using $name, $vlanID, $virtualSwitch, and $cluster.

Let’s do the same thing, but where we’re prompted for the values each time.

$name = Read-Host -Prompt "Enter the name of the new Portgroup (ex: Management Network)"
$vlanId = Read-Host -Prompt "Enter the VLAN Id number for the Portgroup (ex: 13)"
$virtualSwitch = Read-Host -Prompt "Enter the name of the Virtual Switch for Portgroup (ex: vSwitch1)"
$cluster = Read-Host -Prompt "Enter the name of the cluster for this Portgroup (ex: Cluster1)"

I saved the variables above as a file named “addPortgroup.ps1” in the C:\Scripts directory. Running that script in PowerShell prompted for my input for each of those lines. Instead of updating a script file each time I need to add a new Portgroup, I can run the script and enter the values myself.

Now that we’ve recorded these values, let’s start using them.

First off we need to create a new portgroup tag since we’re adding a new portgroup. We use a variable name (in this case $newPortgroup) to define where this tag will live. $xmlConfig.config.Portgroups is the parent of each of the Portgroups we currently have. What we’re doing here is saying make a change to by adding a new element called .

$newPortgroup = $xmlConfig.config.Portgroups.AppendChild($xmlConfig.CreateElement("Portgroup"))

Once we do that, now we’re going to start adding those attributes we already defined. We’ll start with name.

$newPortgroup.SetAttribute("Name",$name)

In the new Portgroup element we created, we set an attribute for and set it to the value of $name (“App Network” for our example).

Now, we can repeat that process for each attribute just like above and save our work (I’ll show how to save in a later step), but if we do that our XML formatting may not be what we’re looking for.

On line 20 of our sample.xml file we see how this data gets saved.

As you can see each attribute is added on the same line. Maybe this works for you, and if so, great. For me, I wanted to maintain the existing formatting, so there is a little more work to do.

Now we need to add each remaining attribute as a child to the already created “App Network” portgroup. We do that with the following command.

$newvlanIdAttribute = $newPortgroup.AppendChild($xmlConfig.CreateElement("vlanId"))
$newvlanIdValue = $newvlanIdAttribute.AppendChild($xmlConfig.CreateTextNode($vlanId))

The first line creates a new attribute called “vlanId” that’s been added to our new then the second line set the value of that attribute to $vlanId (VLAN 31 for this example).

We can now add Virtual Switch and Cluster the exact same way.

$newvirtualSwitchAttribute = $newPortgroup.AppendChild($xmlConfig.CreateElement("virtualSwitch"))
$newvirtualSwitchValue = $newvirtualSwitchAttribute.AppendChild($xmlConfig.CreateTextNode($virtualSwitch))
$newclusterAttribute = $newPortgroup.AppendChild($xmlConfig.CreateElement("cluster"))
$newclusterValue = $newclusterAttribute.AppendChild($xmlConfig.CreateTextNode($cluster))

With all the new elements created and the values set, we need to save this configuration. If we close down PowerShell right now none of our updates are saved. Save using the following command

$xmlConfig.Save($xmlFile)

Now that we’ve updated the xml file, let’s see what it looks like In PowerShell. We’ll need to re-check the contents of the XML file as it changed since we lasted checked.

$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

And now let’s look at $xmlConfig.config.portgroup.portgroups

And if we look at the contents of the XML file we can see that “App Network” matches the layout of our other portgroups

And here is what the script looks like all together:

#Define XML file and Get its contents
$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

#Define variables and prompt for input
$name = Read-Host -Prompt "Enter the name of the new Portgroup (ex: Management Network)"
$vlanId = Read-Host -Prompt "Enter the VLAN Id number for the Portgroup (ex: 13)"
$virtualSwitch = Read-Host -Prompt "Enter the name of the Virtual Switch for Portgroup (ex: vSwitch1)"
$cluster = Read-Host -Prompt "Enter the name of the cluster for this Portgroup (ex: Cluster1)"

#Create a new XML element with the input entered above and save
$newPortgroup = $xmlConfig.config.Portgroups.AppendChild($xmlConfig.CreateElement("Portgroup"));
$newPortgroup.SetAttribute("Name",$name);
$newvlanIdAttribute = $newPortgroup.AppendChild($xmlConfig.CreateElement("vlanId"));
$newvlanIdValue = $newvlanIdAttribute.AppendChild($xmlConfig.CreateTextNode($vlanId));
$newvirtualSwitchAttribute = $newPortgroup.AppendChild($xmlConfig.CreateElement("virtualSwitch"));
$newvirtualSwitchValue = $newvirtualSwitchAttribute.AppendChild($xmlConfig.CreateTextNode($virtualSwitch));
$newclusterAttribute = $newPortgroup.AppendChild($xmlConfig.CreateElement("cluster"));
$newclusterValue = $newclusterAttribute.AppendChild($xmlConfig.CreateTextNode($cluster));
$xmlConfig.Save($xmlFile)

Getting Values from XML Using PowerShell

Working on a recent project I was tasked with maintaining VMware host configuration via XML files. The goal was to have a central location to modify the settings of a host (DNS, vmkernel interfaces, vswitch config, port groups) without having to update each host by hand. This lead me down the path of using PowerShell with XML files as the configuration source.

Below is the sample of my XML file.

What we have here is 3 port groups (Management Network, VM Network, Web Network) with a VLAN, Virtual Switch, and Cluster defined. The entire file sits inside the “config” tags. Each portgroup lives inside the “portgroups” tag, and the values for each portgroup live inside the individual “portgroup” tags.

Below is a sample command to get values from an XML file. We pass the file location as a variable and then we store all those values inside another variable to make working with the values easier.

$xmlFile = "C:\Scripts\sample.xml"
$xmlConfig = [System.Xml.XmlDocument](Get-Content $xmlFile)

And once we type in $xmlConfig into Powershell we can see that it is pulling in the data from our XML file.

We can see the “config” section, but how do we dig deeper? Type in $xmlconfig.config and let’s look at the output

Now we can see the “portgroups” section. Let’s go deeper and see what’s inside of that by typing the following:

$xmlconfig.config.portgroups

Nice! Now we can see all the portgroups we have defined. In order to get detail on each of these, we can type $xmlconfig.config.portgroups.portgroup and we’ll get a list of all the portgroups and all their values.

Now let’s say we are only concerned about retrieving values from one of those portgroups. We can add a Where clause to find only the Portgroups that exist on vSwitch1 as an example with the following command:

$xmlconfig.config.portgroups.portgroup | Where {$_.virtualswitch -eq "vSwitch1"}

Grabbing values out of an XML file is pretty straightforward. In the next post we’ll talk about how to add information to an XML file.