Large File upload to ASP.NET Core 3.0 Web API fails due to Request Body to Large - asp.net-mvc

Question

I have an ASP.NET Core 3.0 Web API endpoint that I have set up to allow me to post large audio files. I have followed the following directions from MS docs to set up the endpoint.
https://learn.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-3.0#kestrel-maximum-request-body-size
When an audio file is uploaded to the endpoint, it is streamed to an Azure Blob Storage container.
My code works as expected locally.
When I push it to my production server in Azure App Service on Linux, the code does not work and errors with
Unhandled exception in request pipeline: System.Net.Http.HttpRequestException: An error occurred while sending the request. ---> Microsoft.AspNetCore.Server.Kestrel.Core.BadHttpRequestException: Request body too large.
Per advice from the above article, I have configured incrementally updated Kesterl with the following:
.ConfigureWebHostDefaults(webBuilder =>
{
webBuilder.UseKestrel((ctx, options) =>
{
var config = ctx.Configuration;
options.Limits.MaxRequestBodySize = 6000000000;
options.Limits.MinRequestBodyDataRate =
new MinDataRate(bytesPerSecond: 100,
gracePeriod: TimeSpan.FromSeconds(10));
options.Limits.MinResponseDataRate =
new MinDataRate(bytesPerSecond: 100,
gracePeriod: TimeSpan.FromSeconds(10));
options.Limits.RequestHeadersTimeout =
TimeSpan.FromMinutes(2);
}).UseStartup<Startup>();
Also configured FormOptions to accept files up to 6000000000
services.Configure<FormOptions>(options =>
{
options.MultipartBodyLengthLimit = 6000000000;
});
And also set up the API controller with the following attributes, per advice from the article
[HttpPost("audio", Name="UploadAudio")]
[DisableFormValueModelBinding]
[GenerateAntiforgeryTokenCookie]
[RequestSizeLimit(6000000000)]
[RequestFormLimits(MultipartBodyLengthLimit = 6000000000)]
Finally, here is the action itself. This giant block of code is not indicative of how I want the code to be written but I have merged it into one method as part of the debugging exercise.
public async Task<IActionResult> Audio()
{
if (!MultipartRequestHelper.IsMultipartContentType(Request.ContentType))
{
throw new ArgumentException("The media file could not be processed.");
}
string mediaId = string.Empty;
string instructorId = string.Empty;
try
{
// process file first
KeyValueAccumulator formAccumulator = new KeyValueAccumulator();
var streamedFileContent = new byte[0];
var boundary = MultipartRequestHelper.GetBoundary(
MediaTypeHeaderValue.Parse(Request.ContentType),
_defaultFormOptions.MultipartBoundaryLengthLimit
);
var reader = new MultipartReader(boundary, Request.Body);
var section = await reader.ReadNextSectionAsync();
while (section != null)
{
var hasContentDispositionHeader = ContentDispositionHeaderValue.TryParse(
section.ContentDisposition, out var contentDisposition);
if (hasContentDispositionHeader)
{
if (MultipartRequestHelper
.HasFileContentDisposition(contentDisposition))
{
streamedFileContent =
await FileHelpers.ProcessStreamedFile(section, contentDisposition,
_permittedExtensions, _fileSizeLimit);
}
else if (MultipartRequestHelper
.HasFormDataContentDisposition(contentDisposition))
{
var key = HeaderUtilities.RemoveQuotes(contentDisposition.Name).Value;
var encoding = FileHelpers.GetEncoding(section);
if (encoding == null)
{
return BadRequest($"The request could not be processed: Bad Encoding");
}
using (var streamReader = new StreamReader(
section.Body,
encoding,
detectEncodingFromByteOrderMarks: true,
bufferSize: 1024,
leaveOpen: true))
{
// The value length limit is enforced by
// MultipartBodyLengthLimit
var value = await streamReader.ReadToEndAsync();
if (string.Equals(value, "undefined",
StringComparison.OrdinalIgnoreCase))
{
value = string.Empty;
}
formAccumulator.Append(key, value);
if (formAccumulator.ValueCount >
_defaultFormOptions.ValueCountLimit)
{
return BadRequest($"The request could not be processed: Key Count limit exceeded.");
}
}
}
}
// Drain any remaining section body that hasn't been consumed and
// read the headers for the next section.
section = await reader.ReadNextSectionAsync();
}
var form = formAccumulator;
var file = streamedFileContent;
var results = form.GetResults();
instructorId = results["instructorId"];
string title = results["title"];
string firstName = results["firstName"];
string lastName = results["lastName"];
string durationInMinutes = results["durationInMinutes"];
//mediaId = await AddInstructorAudioMedia(instructorId, firstName, lastName, title, Convert.ToInt32(duration), DateTime.UtcNow, DateTime.UtcNow, file);
string fileExtension = "m4a";
// Generate Container Name - InstructorSpecific
string containerName = $"{firstName[0].ToString().ToLower()}{lastName.ToLower()}-{instructorId}";
string contentType = "audio/mp4";
FileType fileType = FileType.audio;
string authorName = $"{firstName} {lastName}";
string authorShortName = $"{firstName[0]}{lastName}";
string description = $"{authorShortName} - {title}";
long duration = (Convert.ToInt32(durationInMinutes) * 60000);
// Generate new filename
string fileName = $"{firstName[0].ToString().ToLower()}{lastName.ToLower()}-{Guid.NewGuid()}";
DateTime recordingDate = DateTime.UtcNow;
DateTime uploadDate = DateTime.UtcNow;
long blobSize = long.MinValue;
try
{
// Update file properties in storage
Dictionary<string, string> fileProperties = new Dictionary<string, string>();
fileProperties.Add("ContentType", contentType);
// update file metadata in storage
Dictionary<string, string> metadata = new Dictionary<string, string>();
metadata.Add("author", authorShortName);
metadata.Add("tite", title);
metadata.Add("description", description);
metadata.Add("duration", duration.ToString());
metadata.Add("recordingDate", recordingDate.ToString());
metadata.Add("uploadDate", uploadDate.ToString());
var fileNameWExt = $"{fileName}.{fileExtension}";
var blobContainer = await _cloudStorageService.CreateBlob(containerName, fileNameWExt, "audio");
try
{
MemoryStream fileContent = new MemoryStream(streamedFileContent);
fileContent.Position = 0;
using (fileContent)
{
await blobContainer.UploadFromStreamAsync(fileContent);
}
}
catch (StorageException e)
{
if (e.RequestInformation.HttpStatusCode == 403)
{
return BadRequest(e.Message);
}
else
{
return BadRequest(e.Message);
}
}
try
{
foreach (var key in metadata.Keys.ToList())
{
blobContainer.Metadata.Add(key, metadata[key]);
}
await blobContainer.SetMetadataAsync();
}
catch (StorageException e)
{
return BadRequest(e.Message);
}
blobSize = await StorageUtils.GetBlobSize(blobContainer);
}
catch (StorageException e)
{
return BadRequest(e.Message);
}
Media media = Media.Create(string.Empty, instructorId, authorName, fileName, fileType, fileExtension, recordingDate, uploadDate, ContentDetails.Create(title, description, duration, blobSize, 0, new List<string>()), StateDetails.Create(StatusType.STAGED, DateTime.MinValue, DateTime.UtcNow, DateTime.MaxValue), Manifest.Create(new Dictionary<string, string>()));
// upload to MongoDB
if (media != null)
{
var mapper = new Mapper(_mapperConfiguration);
var dao = mapper.Map<ContentDAO>(media);
try
{
await _db.Content.InsertOneAsync(dao);
}
catch (Exception)
{
mediaId = string.Empty;
}
mediaId = dao.Id.ToString();
}
else
{
// metadata wasn't stored, remove blob
await _cloudStorageService.DeleteBlob(containerName, fileName, "audio");
return BadRequest($"An issue occurred during media upload: rolling back storage change");
}
if (string.IsNullOrEmpty(mediaId))
{
return BadRequest($"Could not add instructor media");
}
}
catch (Exception ex)
{
return BadRequest(ex.Message);
}
var result = new { MediaId = mediaId, InstructorId = instructorId };
return Ok(result);
}
I reiterate, this all works great locally. I do not run it in IISExpress, I run it as a console app.
I submit large audio files via my SPA app and Postman and it works perfectly.
I am deploying this code to an Azure App Service on Linux (as a Basic B1).
Since the code works in my local development environment, I am at a loss of what my next steps are. I have refactored this code a few times but I suspect that it's environment related.
I cannot find anywhere that mentions that the level of App Service Plan is the culprit so before I go out spending more money I wanted to see if anyone here had encountered this challenge and could provide advice.
UPDATE: I attempted upgrading to a Production App Service Plan to see if there was an undocumented gate for incoming traffic. Upgrading didn't work either.
Thanks in advance.
-A

Answer 1

Currently, as of 11/2019, there is a limitation with the Azure App Service for Linux. It's CORS functionality is enabled by default and cannot be disabled AND it has a file size limitation that doesn't appear to get overridden by any of the published Kestrel configurations. The solution is to move the Web API app to a Azure App Service for Windows and it works as expected.
I am sure there is some way to get around it if you know the magic combination of configurations, server settings, and CLI commands but I need to move on with development.