Need Workaround for API URL Suffix Constraint in Azure API Management

Question

Need Workaround for API URL Suffix Constraint in Azure API Management

Deepakraj P 20

Description

We are in the process of migrating APIs from Mashery to Azure API Management. As part of this, we have the following requirement:

We have two APIs that are currently served without any API URL suffix (i.e., the endpoint is the root /).

The client systems cannot update or change the existing endpoint URLs, so any alteration in the URL structure—such as adding /api1 or /api2 as suffixes—will break integrations.

Problem

Azure API Management enforces unique API URL suffixes across the entire instance, which means we cannot assign / as the suffix to more than one API—even if they are intended to be served through different domains.

🛠️ What we’re trying

We have added custom domains (e.g., a.hummingbot.in and b.hummingbot.in) to APIM, hoping we can map:

https://a.hummingbot.in/ → API 1 (with no suffix)

https://b.hummingbot.in/ → API 2 (with no suffix)

But the suffix conflict still prevents us from assigning / to both APIs—even though the hostnames are different.

Request

We are looking for a workaround or best practice that will allow us to:

Serve multiple APIs with the same API URL suffix (ideally /)
Avoid changing client endpoints
Possibly leverage custom domains or self-hosted gateway routing, if applicable

Can you please advise whether Azure APIM supports this through any configuration workaround, host-based routing, or other pattern?

Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-07-25T13:23:24.29+00:00

@Deepakraj P

It appears that you're encountering an issue with Azure API Management related to the URL suffix restriction. Specifically, since your APIs are currently served at the root path (/) and the client systems can't adapt to changes in the URL structure, you're in a bit of a bind with the unique suffix requirement enforced by Azure APIM.

Here's a possible workaround you might consider:

Custom Domains: You can indeed leverage custom domains, as you're already attempting to do. Ensure that your custom domains are set up correctly for the APIM instance. The key here is to assign a different API Management service instance for each custom domain, each having its root endpoint configured for each respective API. This approach allows you to bypass the URL suffix conflict entirely.

Path-based Routing with Application Gateway: Another option is to use Azure Application Gateway with path-based routing. You can set up your Application Gateway to listen on the root path and then route requests to the appropriate backend API based on the hostname or any specific header values you might include. This would allow you to maintain the desired root URL structure while serving two different APIs.

Self-Hosted Gateway: If you want further control, consider using Azure API Management's Self-Hosted Gateway. This allows you to host the gateway in your own data center (or in Azure) and customize routing without being limited by the standard APIM constraints.

It’s important to verify that you are operating within the Premium or Developer tiers of API Management, as these support multiple custom domains.

I hope this provides a useful starting point for your API migration.
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Deepakraj P 20 Reputation points

2025-07-25T14:14:02.3066667+00:00

I missed to mention that the APIs are hosted on clien't datacenter, and using self-hosted gateway we're trying to import and manage APIs. Custom domains are already added to the instance whereas we still don't have option or control to assign APIs to respective domain. I believe we tried to have multiple gateways in the environment, still we can't have individual gateway for each of the hundreds of APIs.

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Sai Prabhu Naveen Parimi 3,470 Reputation points Microsoft External Staff Moderator

2025-07-25T13:23:24.29+00:00

@Deepakraj P

It appears that you're encountering an issue with Azure API Management related to the URL suffix restriction. Specifically, since your APIs are currently served at the root path (/) and the client systems can't adapt to changes in the URL structure, you're in a bit of a bind with the unique suffix requirement enforced by Azure APIM.

Here's a possible workaround you might consider:

Custom Domains: You can indeed leverage custom domains, as you're already attempting to do. Ensure that your custom domains are set up correctly for the APIM instance. The key here is to assign a different API Management service instance for each custom domain, each having its root endpoint configured for each respective API. This approach allows you to bypass the URL suffix conflict entirely.

Path-based Routing with Application Gateway: Another option is to use Azure Application Gateway with path-based routing. You can set up your Application Gateway to listen on the root path and then route requests to the appropriate backend API based on the hostname or any specific header values you might include. This would allow you to maintain the desired root URL structure while serving two different APIs.

Self-Hosted Gateway: If you want further control, consider using Azure API Management's Self-Hosted Gateway. This allows you to host the gateway in your own data center (or in Azure) and customize routing without being limited by the standard APIM constraints.

It’s important to verify that you are operating within the Premium or Developer tiers of API Management, as these support multiple custom domains.

I hope this provides a useful starting point for your API migration.
Deleted

This comment has been deleted due to a violation of our Code of Conduct. The comment was manually reported or identified through automated detection before action was taken. Please refer to our Code of Conduct for more information.
Deepakraj P 20 Reputation points

2025-07-25T14:14:02.3066667+00:00

I missed to mention that the APIs are hosted on clien't datacenter, and using self-hosted gateway we're trying to import and manage APIs. Custom domains are already added to the instance whereas we still don't have option or control to assign APIs to respective domain. I believe we tried to have multiple gateways in the environment, still we can't have individual gateway for each of the hundreds of APIs.

Answer 1

Ievgen Zasid 75

Hello @Deepakraj P ,

To achieve seamless API migration objective you need to implement the following idea/steps:

Onboard 2 APIs to 1 API Management instance
https://myorg.azure-api.net/api1/
https://myorg.azure-api.net/api2/
Spin up Azure Application Gateway with 2 http listeners in front of API Management
https://a.hummingbot.in/
https://b.hummingbot.in/
Implement the following routing leveraging "Rewrite a URL" capability - https://learn.microsoft.com/en-us/azure/application-gateway/rewrite-url-portal https://a.hummingbot.in/ => https://myorg.azure-api.net/api1/ https://b.hummingbot.in/ => https://myorg.azure-api.net/api2/

As a bonus you can configure Azure Web Application Firewall(WAF) on Application Gateway layer which is not possible to do on API Management. That should increase the security for your API Integrations.

If you find my recommendations helpful to you please mark my answer as accepted or let me know if you have any additional questions.

Deepakraj P 20 Reputation points

2025-07-25T14:10:41.3133333+00:00

I missed to mention that the APIs are hosted on clien't datacenter, and using self-hosted gateway we're trying to import and manage APIs. To make sure it works what I can do now based on the given information?

Ievgen Zasid 75

@Deepakraj P ,

As an option you can do the following:

Configure 2 custom domains for self-hosted API Gateway(this will work only for Developer or Premium tier) https://learn.microsoft.com/en-us/azure/api-management/api-management-howto-configure-custom-domain-gateway.
https://a.hummingbot.in/
https://b.hummingbot.in/
Onboard a facade API into the root "/"
Implement routing in facade API policy like below

Hope that helps.

   <policies>
    <inbound>
        <base />
        <choose>
            <when condition="@(context.Request.Url.Host == \"a.hummingbot.in\")">
                <set-backend-service base-url="https://backend-service-a.azurewebsites.net" />
            </when>
            <when condition="@(context.Request.Url.Host == \"b.hummingbot.in\")">
                <set-backend-service base-url="https://backend-service-b.azurewebsites.net" />
            </when>
            <otherwise>
                <!-- Optional: Define a default backend or return an error -->
                <return-response>
                    <set-status code="404" reason="Not Found" />
                    <set-header name="Content-Type" exists-action="override">
                        <value>application/json</value>
                    </set-header>
                    <set-body>{"message": "No backend found for the requested host."}</set-body>
                </return-response>
            </otherwise>
        </choose>
    </inbound>
    <outbound>
        <base />
    </outbound>
</policies>

Ievgen Zasid 75 Reputation points

2025-07-28T19:31:29.5866667+00:00

@Deepakraj P , did my solution help you? Please mark it as answer or let me know if you have any additional question. Thanks

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Need Workaround for API URL Suffix Constraint in Azure API Management

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