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Its easy to deploy Citrix products into a Public Cloud such as Microsoft Azure, however just assuming that as it is in the Microsoft Cloud it will be resilient is often the reason that services hosted in the cloud fail to operate as expected.
This article will walk you through the process of making sure your Citrix StoreFront implementation in Microsoft Azure will stay up and operational at all times.
I am certainly NOT saying that this could or should replace the Citrix NetScaler as a load balancer however with the current limitations that the Citrix NetScaler has in Microsoft Azure it is a good option for keeping some form of fail over in your StoreFront deployment in the cloud.
This article assumes that you already have a working environment in Azure and that you have 2 StoreFront servers, on the domain, StoreFront installed and working as a Server Group.
NOTE: In this example I have 2 StoreFront servers running but NOT as a single server group. This is because I want the appearance of each store to be different to demonstrate the load balancing working.
So, lets get to it…
As you can see I have 2 StoreFront servers running in the same region ready to go.
Step 1 – Static IP Addressing
First open up Windows Powershell for Azure and connect to your subscription that the servers are running in and type in the commands below for each StoreFront server
NOTE: The servers may restart once you assign the IP Addresses!
Step 2 – Availability Set
You need to add both of your StoreFront servers to a Availability Set. The reason for this is that when Microsoft patch the services in Azure they do not take into account the workloads you are running. Therefore by creating an availability set and adding both StoreFront servers into it you are instructing Microsoft to keep the servers on separate racks in the datacenter and also on different patching cycles.
Navigate to your primary StoreFront server and select Configure
Select Create an Availability Set
Give the Availability Set a Name
Click Save
Confirm the Save action – be aware that the server may be restarted as a result of this being created
If you click on Dashboard you will see that the availability set has been created but Azure is warning you that there is only 1 instance running in it currently
Navigate to your secondary StoreFront server and click Configure
Select your Availability Set from the drop down list provided
Click Save
Confirm the save action – NOTE: You server may be restarted when you apply this
At this point your Availability Set has been created but you want to confirm that your 2 StoreFront servers are running on different Patch and Fault Domains.
Click on Cloud Services
Select the Cloud Service that both your StoreFront servers are running in and select Instances. Here you should see that the Update Domain and Fault Domain are different for both servers. This means that the servers will never be down at the same time unless Microsoft loose a datacenter
Step 3 – Check Storage Replication
You will need to ensure that your Storage is Locally Redundant. To check this click on Storage
Select Configure and ensure that Locally Redundant is selected
Step 4 – Create Internal Load Balancer
Next you will need to create an Internal Load Balancer in Microsoft Azure with 2 nodes in pointing to each of your StoreFront Servers
First open up Windows Powershell for Azure and connect to your subscription. Create a new Internal Load Balancer by typing in the below command. ServiceName is the name of the cloud service that you want the ILB in, Give it a Name, tell it what subnet you want the Load Balancer on and give it a static IP Address that is not in use.
Next type in the below command to ensure that the Internal Load Balancer has been created correctly
Next you need to add an End Point for your primary StoreFront server. Type in the following command giving the End Point a Name, Internal and External Port, Protocol and a Load Balanced Set Name
At this point you have set up a load balancer and bound port 80 from your primary StoreFront server to it. You could test this by opening up a browser and putting in http://192.168.1.100 but that does not look so nice, therefore you should create a DNS record in your dns lookup zone and point it to the Load Balancer IP Address
Once you have done this test that it is working by performing a nslookup on the new domain name
You should now be able to open up a browser and connect to your new dns name, whick in turn will direct you to the primary StoreFront server in your Load Balanced set
Switch back to your Azure Powershell window and add the second node (Secondary StoreFront server) to the Load Balancer
OPTIONAL: You can check the End Points running on the StoreFront servers by entering the command below
Step 5 – Configure NetScaler
You need to change the StoreFront Session Settings on your NetScaler to reflect the new Load Balancer IP Address. Login to your NetScaler and Open up the Session Policies section under the NetScaler Gateway Node
Edit your Session Profile and change the Home Page Address to point to your new DNS record for StoreFront (pointing at teh Load Balancer IP Address) – In this case I have just put in the IP Address
Do the same for the Published Application settings
Save your NetScaler Config
Step 6 – Test the Fail Over
For this example I have changed the banner colour for StoreFront
BMUK-SF
BMUK-SF-2
Shutdown StoreFront Server 2
Log into your NetScaler Gateway
Your Apps will be displayed – Note the RED background – this session is being directed to BMUK-SF
Log out of your NetScaler Gateway and reverse the servers turned on. Now BMUK-SF2 is ON and BMUK-SF is powered OFF
Log back into your NetScaler Gateway
Your Apps will be displayed again, however note the GREEN background – this session is being directed to BMUK-SF-2
Thats it! Thats how to deploy a highly available Citrix StoreFront delivery in the Microsoft Azure Public Cloud. Hope this helped some of you out, as always please comment and share.
Laters,
b@m