Azure Traffic Manager is used to mange the traffic of your Internet resources and monitor the health of those resources. These resources may reside outside the Azure as well.
This post is focused on Azure Web Apps and how to manage multiple web apps using Azure Traffic Manager and handling deployments using new TFBuild of VSTS.
Consider a scenario of having two deployments of your site in different regions, one in the South East Asia and the other one in the North Europe. The site is deployed in two places in order to cater the users from each region with minimum latency. Traffic Manager is deployed in place in order determine the resource usage and directs the clients to the right location.
First when a client requests the site, the request hits the DNS, the DNS records have the mapping of the URL to the Traffic Manager DNS and it makes a lookup request to the corresponding Traffic Manager DNS.
Then the Traffic Manager DNS will deliver the right IP address of the web app based on the configured routing rules. This IP address will be given to the client, subsequent requests from the client will be sent directly to the obtained IP address until the local DNS cache expires.
Setting up Traffic Manager
Create a Traffic Manager space and you will get a URL like domainprefix.trafficmanager.net(The below sample I generated when while sipping my iced tea and named the Traffic Manager mytea). When creating the Traffic Manager you will configure the load balancing mechanism. Here I simply chose Performance as my load balancing mechanism since I want to reduce the latency of the site based on the geographic region it is accessed from.
Then you add the web apps you want to manage to the Traffic Manager as endpoints. (Note, only web apps running in the standard or upper tier are allowed to be added to the Traffic Manager)
I added two web apps one in South East Asia and the other one in the North Europe as you can see in the below image.
How does this work ?
After creating the Traffic Manager profile (mytea.trafficmanager.net), you will add the endpoints. When adding the endpoints, the Traffic Manager will register its URL as one of the domain names in mentioned web apps. The web app URLs are registered as CNAME entries of the Traffic Manager DNS.
How does this work when you have a custom domain ?
When you have a custom domain, example abc.com you register that domain in the above section, and you configure the azure web app URL as a CNAME record in the abc.com domain. Now when you type abc.com in the browser you will be served with the site.
In a more simpler way, the DNS entry which holds the A record of abc.com should have CNAME record to point to the Azure web app.
When using the Traffic Manager, you register the traffic manager URL as a CNAME entry in the abc.com.
Managing deployments to multiple web apps
This had been one of the well known and highly anticipated requirement of CI/CD pipeline. But with the new TFBuilds introduced in Visual Studio Team Services it is very simple. You can simply add multiple deployments steps in your build definition and the TFBuild will take care of your deployment.
Below image shows a build definition with two azure web app deployment endpoints.
Now you can type the Traffic Manager URL in the browser with the http/https prefix and you will be served with the site.
In order to check the performance routing of the region I changed the home page of the site deployed in North Europe. Then I browsed the site using a VM deployed in North Europe and browsed it from local machine where my physical location is closer to the South East Asia.
You can see that two different sites are served based on the location from where I’m browsing the site.