All the microservices that we have created in this recipe are anonymous, which means they are publicly accessible to everyone. In order to make them secure, you need to follow either of the approaches recommended in Chapter 9, Implementing Best Practices for Azure Functions.
The Azure Function proxies also allow you to intercept the original request and, if required, you can add new parameters and pass them to the backend API. Similarly, you can add additional parameters and pass the response back to the client application. You can learn more about Azure Function proxies in the official documentation at https://docs.microsoft.com/en-us/azure/azure-functions/functions-proxies.