Testing specific Azure Web Site Instance

Question

I have an Azure Web Site configured to use multiple (2) instances:

Azure Configuration

I have a service bus that should pass messages (ie Cache Evict) between the instances. I need to test this mechanism.

In a conventional (on premise) system I would point a browser to instance 1 (ie http://myserver1.example.com), perform an action, then point my browser to the other instance (http://myserver2.example.com) to test.

However, in Azure I can't see a way to hit a specific instance. Is it possible? Or is there an alternative way to to run through this test scenario (act on instance 1, ensure instance 2 behaves appropriately)?

I don't believe you can have such level of control in Azure. It's a question of load balancing and it's done automatically. — Kenan Zahirovic, Nov 27 '14 at 16:29
Can I take instances out of the load balancer, but still keep them alive? That way I could preform the test by controlling which instance is in load balancer? — Philip Pittle, Nov 27 '14 at 16:30
http://azure.microsoft.com/blog/2014/10/30/azure-load-balancer-new-distribution-mode/ — Kenan Zahirovic, Nov 27 '14 at 16:33

score 4 · Accepted Answer · answered Nov 28 '14 at 03:22

Unfortunately, there isn't an official way of doing this. However, you can achieve that by setting a cookie called ARRAffinity on your request.

Try hitting your site from any client (Chrome, Firefox, curl, httpie, etc) and inspect the response headers that you are getting back.

For example in curl you would do

curl -I <siteName>.azurewebsites.net

you would get this

HTTP/1.1 200 OK
Content-Length: 2
Content-Type: text/html
Last-Modified: Wed, 17 Sep 2014 16:57:26 GMT
Accept-Ranges: bytes
ETag: "2ba0757598d2cf1:0"
Server: Microsoft-IIS/8.0
X-Powered-By: ASP.NET
Set-Cookie: ARRAffinity=<very long hash>; Path=/;Domain=<siteName>.azurewebsites.net
Date: Fri, 28 Nov 2014 03:13:07 GMT

what you are interested in is the ARRAFinity if you send couple of request you would notice that hash will keep changing between 2 values that represent your 2 instances.

Set that in your Cookie header on your request will guarantee it going to one of the instances and not the other.

curl --cookie ARRAfinity=<one of the hashes you got> <siteName>.azurewebsites.net

That did it! A bit annoying having to mine / manipulate cookies but at the end of the day it wasn't too big a deal. — Philip Pittle, Nov 28 '14 at 13:12

Testing specific Azure Web Site Instance

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