CODEWITHSUNDEEP
azureurl-rewritingazure-api-management
Dave061
Dave061

Reputation: 215

Azure APIM foward custom header and change backend URI

I am a newbie with azure APIM. I am trying to implement such a functionality where I need to make sure that when the client sends the request with the proper subscription-key and wants to add a custom header to route to the appropriate backend service URL. Without adding a Web Service URL only API URL Suffix I have. Otherwise, I have to create 10 same apis with little changes in the URL.

The client adds the custom header in his request to base URL https://my-app-api.azure-api.net/api/customers

Ocp-Apim-Subscription-Key: Keys-for-auth

"X-subjectName": my-subject-value

When the request came to the backend to override the URI with that header, I need to extract the custom header from the call and override the backend URI. Can I do it via policies?

After overriding my backend URI it should look like this: https://my.api.com/api/v1/my-subject-value /customers

Thank you!

Policy from the comments:

<inbound> 
     <set-variable name="myvar" value="@(context.Request.Headers.GetValueOrDefault("my-header",""))" /> 
     <set-backend-service base-url="my-api-backend.com{{myvar}}" />    
</inbound>

Upvotes: 1

Views: 3535

Answers (1)

Markus Meyer
Markus Meyer

Reputation: 3967

Please get the value of the variable this way:
context.Variables.GetValueOrDefault<string>("myvar")

With the rewrite-uri the value of the variable can be appended to URL:

<inbound> 
     <set-variable name="myvar" value="@(context.Request.Headers.GetValueOrDefault("my-header",""))" /> 
     <set-backend-service base-url="my-api-backend.com" />    
     <rewrite-uri template="@("/" + context.Variables.GetValueOrDefault<string>("myvar"))" copy-unmatched-params="false" />        
</inbound>

Please find below a complete working example for demonstration:

<policies>
    <inbound>
        <base />
        <set-variable name="myvar" value="@(context.Request.Headers.GetValueOrDefault("my-header",""))" />
        <rewrite-uri template="@("/?name=" + context.Variables.GetValueOrDefault<string>("myvar"))" copy-unmatched-params="false" />
        <set-backend-service base-url="https://api.agify.io" />
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

Request with custom header:

enter image description here

Result from trace:

enter image description here

Upvotes: 2

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