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) }

Removing Values in XML Using PowerShell

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)

Adding Values to XML Using PowerShell