Can Azure Api Management expose OpenAPI documentation?

Question

We have some Azure Functions exposed through Api Management? Can Api Management expose a /swagger endpoint automatically, the same way the Swashbuckle package does for api's in Asp.Net.

Answer 1

You can expose your openapi documentation through the API itself. The documentation of an API can be requested on

https://management.azure.com/subscriptions/[subscriptionid]/resourceGroups/[resourcegroupname]/Microsoft.ApiManagement/service/[servicename]/apis/[apiid]?export=true&format=openapi&api-version=2021-01-01-preview

Just create an additional operation (ex. openapi.yaml) on your API, call the url above through a custom policy and return the result. You can use the following policy

<policies>
    <inbound>
        <base />
        <send-request mode="new" response-variable-name="result" timeout="300" ignore-error="false">
            <set-url>@("https://management.azure.com/subscriptions/{{azure-subscriptionid}}/resourceGroups/{{azure-resourcegroup}}/providers/Microsoft.ApiManagement/service/" + context.Deployment.ServiceName + "/apis/" + context.Api.Id + "?export=true&format=openapi&api-version=2021-01-01-preview")</set-url>
            <set-method>GET</set-method>
            <authentication-managed-identity resource="https://management.azure.com/" />
        </send-request>
        <return-response>
            <set-status code="200" reason="OK" />
            <set-header name="Content-Type" exists-action="override">
                <value>application/yaml</value>
            </set-header>
            <set-body>@((string)(((IResponse)context.Variables["result"]).Body.As<JObject>()["value"]))</set-body>
        </return-response>
    </inbound>
    <backend>
        <base />
    </backend>
    <outbound>
        <base />
    </outbound>
    <on-error>
        <base />
    </on-error>
</policies>

More info can be found on https://www.devprotocol.com/2021/07/20/expose-openapi-documentation-on-azure-api-management.html

Answer 2

Azure API management cannot automatically generate the swagger page. Azure API management only can provide you the API definition file. Then you can use other tools (such as Swagger UI) with the definition file to generate the page you need.

Besides, Azure API management has provided you the UI(https://youapimanagementname.portal.azure-api.net) to tell you how to use all the APIs.