WilliamLam.com

Thank you for voting! (Top vBlog 2017)

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I had been in meetings all day today and I had noticed my Twitter notifications was going nuts. It was only until my last meeting of the day, which was with Emad, did I learn what was going on. I had no idea the Top vBlog 2017 results were being announced today and when Emad broke the news that I had gotten #1 this year, I was left speechless. I want to thank everyone who voted for me, this recognition truly means a lot coming from the community, so thank you! I also want to congratulate all my fellow bloggers who were also recognized in this years Top vBlog including the special category winners.


Lastly, a huge shoutout to Eric Siebert for running the Top vBlog program and spending countless hours putting everything together, we know its not easy each year and the community really appreciates it. Of course, I could not leave out Eric Wright and Turbonomic who were the sponsors again for this years Top vBlog. Thanks for guys!

If you missed the live-stream earlier (like me), you can watch the full results below. I believe Eric will also be publishing the complete Top vBlog results on his blog soon, so stay tuned for that!

vSphere Content Library versioning 

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A question came up the other day on how versioning is handled when using the vSphere Content Library feature and specifically when you update an existing VM template that already exists in the Content Library (CL, which I will be using throughout the article). Having used CL since vSphere 6.0 which I have also written about it extensively here, I knew that it had a built-in versioning mechanism which would automatically increment as new updates were applied to the VM Templates stored in CL.

One thing that I do not think many folks are aware of is that you can actually retrieve the CL Item Version within the vSphere Web Client. You can do by just adding the "Content Version" column by right clicking on column headers and select show/hide columns to add or remove specific fields.


I figured, this was pretty straight forward and shared my findings with the individual and thought that was it. While working on my Content Library PowerCLI community module, I came to learn there was more than one version that was being returned by the CL API.

Here is an example screenshot showing the three different versions using the Get-ContentLibraryItems (not to be confused with the OOTB Get-ContentLibraryItem cmdlet):


Taking a look at the API documentation, it was still not 100% clear on what all these versions provided and also when would they increment? I reached out to one of the CL Engineers, Eric who then provided me more information on how each of these versions are being used. Lets go through each one of them and I will include an example which also helped me understand how these different "versions" actually work.

Content Version - This particular version will increment as changes are made to the actual file content itself. This is also the same version that is available in the vSphere Web Client UI as shown earlier.

Lets now go through an example workflow to show when this version will get incremented:

  1. Create a new VM called Foo (ContentVersion=N/A)
  2. Clone VM Foo into CL called Foo VM Template (ContentVersion=1)
  3. Clone completes for Foo VM Template (ContentVersion=2) <--The reason this is 2 and not 1 is that when the initial CL Item is created (think of it as a placeholder), the Content Version is incremented
  4. Deploy Foo VM Template to new VM called Bar (ContentVersion=2, no changes on deploy)
  5. Update VM Bar with some changes and clone Bar back to Foo VM Template (ContentVersion=3) <--Changes were made and we now increment the Content Version

Metadata Version - This particular version will only increment for changes made to either the name or description of the CL template.

Version - This particular version is used for concurrency control and this will always increment along with the Metadata Version for local libraries.

Lets now go through an example workflow for a local library to show how these two versions get incremented:

  1. Create a new VM called Foo (MetadataVersion=N/A)
  2. Clone VM Foo into CL called Foo VM Template (MetadataVersion=1, Version=1)
  3. Update the description of Foo VM Template (MetadataVersion=2, Version=2)
  4. Deploy Foo VM Template to new VM called Bar (MetadataVersion=2, Version=2, no changes on deploy)
  5. Update VM Bar with some changes and clone Bar back to Foo VM Template (MetadataVersion=3, Version=3)

Lets now go through an example workflow for a subscribed library to show how these two versions get incremented:

  • Create a new VM called Foo on a local library named CL1 (MetadataVersion=N/A)
  • Clone VM Foo into CL called Foo VM Template (MetadataVersion=1, Version=1)
  • Update the description of Foo VM Template (MetadataVersion=2, Version=2)
  • Create a new subscribed library to CL1 which will download Foo VM Template (MetadataVersion=2, Version=1) <--MetadataVersion must match the publisher, but version does not have to match

After going through a few of these exercises with a few dummy VMs and using my Get-ContentLibaryItems function, I was able to get a better grasp on CL versioning. Hopefully this helpful for anyone who might want to use the CL APIs to track changes between their VM templates and/or files or just being able to see this within the vSphere Web Client UI.

Quick Tip - List all open ports on the VCSA / PSC

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The list of required ports for both a vCenter Server Appliance (VCSA) and Platform Services Controller (PSC) are pretty well documented here (6.5), here (6.0) and here (5.5) for customers who require this information to setup external connectivity within their networking infrastructure. Having said that, it is may not always be clear on what ports are actually opened as they will usually depend on the type of deployment and the services that are running. Instead, some customers have inquired about getting a list of all open ports directly from the VCSA/PSC to ensure they have the actual configuration which can be used to build firewall rules and/or for auditing purposes.

Today, the only method is to login directly into the VCSA/PSC via SSH (you could also use GuestOps API, so that SSH is NOT required) and fetching this information using iptables. Hopefully, in the future, this can be made available as part of the VAMI API since it already covers some basic inbound firewall rule capabilities. In the mean time, below are examples of how to get all the open ports for both VCSA/PSC

Run the following command to view all open ports on VCSA/PSC:

iptables -L port_filter -n --line-numbers


You will notice in the output above, there is also a chain number on the far left side which is associated with each rule. This chain number can be used to inspect the rule further and some rules include a nice alias to help you identify what the port might be used for.

For example, we can run the following to inspect chain rule #30 and find out this port is being used for syslog. If we want the port number, we simply add the -n option.

iptables -L port_filter 30
iptables -L port_filter 30 -n


Not all of the firewall rules have an alias name and even if they do, it still may not be apparent on what service is opening that particular port. We can actually look at the firewall rule definitions which are located under /etc/vmware/appliance/firewall and you will see a JSON file for each of the VCSA/PSC services that require firewall rules to be opened up. For a given port, you can just grep in this directory to identify the service that is requiring the port.

For example, if we take a look at the vmware-syslog, we see that it requires tcp/udp 514 and tcp 1514 under the "rules" array which defines the list of external ports open. You can ignore the internal ports as those are not exposed to the outside world but used by internal services. In case the services are still not clear, you can always reference the port number back to the documentation which I had linked above to get more details about the particular port.