Azure Traffic Manager support with Azure Function Apps

Question

I am trying to use Azure Traffic Manager (GTM) to geographically distribute load to function apps in each region.

I have tried adding an 'app service endpoint' and an 'external endpoint' (including adding the GTM name as a custom CNAME to the function app), but both result in "Error 404 - Web app not found.". The custom CNAME also never adds correctly.

According to the last comment on this post, the ability to do this should now be supported: Setting up a custom domain with an Azure Function app

I am unable to comment back on the post as I am a new user.

Answer 1

I have tried adding an 'app service endpoint' and an 'external endpoint' (including adding the GTM name as a custom CNAME to the function app)

Azure Traffic Manager is only eligible for use with App Services at the 'Standard' level or above as mentioned here. If your function isn't host in an app plan at the 'Standard' level or above, Azure Traffic Manager will not work.

If you are not using 'Standard' or higher level app plan, Azure Functions Proxies would be a workaround for you. Please check following thread which discuss the similar problem.

Azure Functions Traffic Manager

Here is the quick reference from the answer provided by Dakota Kincer.

So the answer I arrived to after Traffic manager didntsupport Azure functions was to overall build 3 Azure functions. I built an East and a West that has my azure function code on it. Then I built a main Azure Function that has 0 code. It only has Azure proxies on it that route to my 2 other Azure Functions. The route is controlled by a variable in the proxy string that is help in the main API app settings. Using %myvariable% you can set part of the url. When I need to publish I switch the variable to the secondary URL location. Update the Primary and then switch the URL to its original primary location. This will have to work for now till traffic manager is integrated into functions or a better solution arises.

I am unable to comment back on the post as I am a new user.

You could modify your post if you want to provide more information.

Answer 2

Traffic Manager supports Azure functions monitoring. You can enable this by going to TM settings -> endpoints -> add endpoint -> choose Azure endpoint type -> App Service for Target resource type -> under Target Resource choose Function app which you want to monitor.

Most likely you want to be able to access function apps under specific domain domain, for example my-domain.com. For that under Custom Header Settings specify host:my-domain.com. You'll need to setup custom domain in function apps configuration too.