How to download a blob from azure storage that goes through an Azure function for request and response?

Question

How to download a blob from azure storage, to a mobile device, that first goes through an Azure function for request and response?

HTTPClient using 1 request & response

mobile device (request) --> function --> blob download

mobile device (response) <-- function <-- blob download

I want to download a blob from a storage container. I want to do this through an Azure function that will process code/logic as the download request and response passes through it. My main question is how can I make the function request the blob from the blob storage container and pass it to the client without having the function download the blob first. Basically I want the blob download to pass-through the function to the client as if the client had requested the blob download directly. I use HTTPClient.

Answer 1

I think from your Azure function you should return a HTTP redirect

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, string path, TraceWriter log) {
    // ... determine the blob you want to download ...

    var response = HttpResponseMessage(HttpStatusCode.Redirect);
    response.Headers.Location = new Uri(/* Azure blob URI goes here */);
    return response;
}

Inspired by this blog post .