Error 406 or 500 when executing function returning HttpResponseMessage<byte[]> on Azure CLI

[sirmamedical]

I am trying to implement a file download using Azure function in java. The function is:

@FunctionName("FileDownload")
@HttpOutput(name="$return", dataType = "binary")
public HttpResponseMessage<byte[]> download(@HttpTrigger(name = "req", methods = {"get"}, route = "download", authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage req, ExecutionContext context) {
    try {
        byte[] bytes = "Simple text file to test download".getBytes("UTF-8");

        HttpResponseMessage<byte[]> response = req.createResponse(200, bytes);
        response.addHeader("Content-Type", "application/octet-stream");
//            response.addHeader("Content-Length", "" + bytes.length);
        response.addHeader("Content-Disposition", "attachment; filename=myfile.txt");
        return response;

    } catch (UnsupportedEncodingException e) {
        context.getLogger().warning("Invalid encoding");
    }

    return req.createResponse(200, "Invalid encoding!".getBytes());
}

Function is executed successfully as it is reported in the log:

[3/15/2018 6:45:49 AM] Function started (Id=d6b40f17-7217-4f6e-8c19-00e3025f3821)
[3/15/2018 6:45:49 AM] Executing 'Functions.FileDownload' (Reason='This function was programmatically called via the host APIs.', Id=d6b40f17-7217-4f6e-8c19-00e3025f3821)
[3/15/2018 6:45:49 AM] Function "FileDownload" (ID: 02ea5ace-c7ff-47b1-816a-03a845973936) invoked by Java Worker
[3/15/2018 6:45:49 AM] Function completed (Success, Id=d6b40f17-7217-4f6e-8c19-00e3025f3821, Duration=57ms)
[3/15/2018 6:45:49 AM] Executed 'Functions.FileDownload' (Succeeded, Id=d6b40f17-7217-4f6e-8c19-00e3025f3821)

The execution in curl produces the following:

$ curl -v http://localhost:7071/api/download
* timeout on name lookup is not supported
*   Trying ::1...
* Connected to localhost (::1) port 7071 (#0)
> GET /api/download HTTP/1.1
> Host: localhost:7071
> User-Agent: curl/7.48.0
> Accept: */*
>
< HTTP/1.1 406 Not Acceptable
< Date: Thu, 15 Mar 2018 07:56:57 GMT
< Content-Type: application/octet-stream
< Server: Kestrel
< Content-Length: 0
< Content-Disposition: attachment; filename=myfile.txt
<
* Connection #0 to host localhost left intact

When I uncomment the line where Content-Length header is set then it produces error 500.

[roastario]

+1 this also affect my application in the same way

@FunctionName("getNetworkMap")
fun getNetworkMap(
        @HttpTrigger(methods = ["get"], dataType = "binary", authLevel = AuthorizationLevel.ANONYMOUS, route = "network-map", name = "in") token: HttpRequestMessage<Any?>,
        @BlobInput(name = "serialisedNetworkMap", dataType = "binary", connection = "AzureWebJobsStorage", path = "networkmap/network-map.ser") networkMap: ByteArray?,
        executionContext: ExecutionContext): HttpResponseMessage<ByteArray> {
    val toReturn = networkMap ?: throw IllegalStateException("no previously serialized networkmap found")
    val response = token.createResponse(200, toReturn)
    response.addHeader("Content-Type", "application/octet-stream")
    return response
}

Causes a 406, and if I don't set the content-type, the runtime seems to be formatting it as a JSON string, which is not what I want. At the moment there literally does not seem to be a way to return a raw byte[] from a function.

What would be ideal is something similar to isRaw in the node.js runtime.

[JunyiYi]

Let's track this issue in #76.