Azure Traffic Manager for switching to different API Management Service

Question

So I'm working on building scripts to deploy Azure resources using the Az modules in PowerShell. I am new to Azure Traffic Manager, so I'm wondering if what we are looking to do is even possible, and if so, how.

We have an API Management Service (APIMS) with a handful of APIs in it that point to a few different web apps within Azure. So the way it works currently is we have a client application that will post to a specific API operation via its APIMS URL.

We are looking at the idea of using Traffic Manager purely for moving traffic from one APIMS to a another in the event that we need to create a new APIMS. I can add the existing APIMS as an endpoint to the Traffic Manager as an external endpoint using its public IP address. But beyond that, here's what I'm unsure of:

• How exactly would traffic actually get routed through the traffic manager, through the APIMS, to the specific API post? (as in, what would the client application need to specify as where it's sending its post?). Or would this even work??
• If we create a new APIMS, can we then simply add that as a new endpoint to the traffic manager (again, as an external endpoint via its IP address), and then delete the old APIMS endpoint?

I did find this question that's similar, but that answer is using Add-AzureTrafficManagerEndpoint as opposed to New-AzTrafficManagerEndpoint, which is what I'm using and apparently does not support -DomainName as a parameter.

Answer 1

Traffic manager does not route traffic, it only does domain name resolution. You could use TM for that. For your custom domain in traffic manager (say contoso.com) you can add CNAME record pointing to contoso.azure-api.net (it's preferable to use CNAME instead of A and APIM service IP may change in certain scenarios). And add SSL certificate in APIM for contoso.com. What will happen in that setup:

1. Client wants to make request to https://contoso.com/myapi
2. Client will perform DNS lookup for contoso.com and see CNAME record pointing to contoso.azure-api.net
3. Client will perform DNS lookup for contoso.azure-api.net and see APIM IP address
4. Client will try to open SSL connection to APIM
5. APIM having SSL certificate available will accept the connection
6. Client will send request.

All this does not require any special configuration from your client apart from setting it up to use "contoso.com" as a hostname for your API. Later if you want to switch to a different APIM service you could go and update TM. Client will not require any changes.

The one thing to know is that this particular setup does not require TM per se. As all you really need is a custom domain from any DNS provider because all you need to do to switch traffic from one APIM to another is update CNAME record.