Buffer too many uploads? - asp.net-mvc

Question

I am trying to upload a large video file. I am using Azure Storage blob. Reading documentation there is warning about using IFormFile at https://learn.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-2.1
It suggests that I stream my data.
Is the follow code creating a buffer there will crash my server , or streaming directly to the storage?
From the View
<form asp-action="Create" enctype="multipart/form-data">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<div class="form-group">
<label asp-for="Name" class="control-label"></label>
<input asp-for="Name" class="form-control" />
<span asp-validation-for="Name" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Description" class="control-label"></label>
<input asp-for="Description" class="form-control" />
<span asp-validation-for="Description" class="text-danger"></span>
</div>
<div class="form-group">
<input asp-for="VideoAsFile" class="form-control" />
<span asp-validation-for="VideoAsFile" class="text-danger"></span>
</div>
<div class="form-group">
<input type="submit" value="Create" class="btn btn-default" />
</div>
</form>
From the controller
public async Task<IActionResult> Create([Bind(" Name,Description,VideoAsFile")] VideoWithFileViewModel video)
{
if (ModelState.IsValid)
{
string imageId;
using (var stream = video.VideoAsFile.OpenReadStream())
{
imageId = videoServices.SaveVideo(stream);
}
var newVideo = new Video()
{
Name = video.Name,
Description = video.Description,
URL = imageId
};
repository.AddVideo(newVideo, User);
repository.SaveAll();
return RedirectToAction(nameof(Index));
}
From the VideoServices
public string SaveVideo(Stream videoStream)
{
CloudBlobClient blobClient=new CloudBlobClient(new Uri(baseUri), credentials);
var imageId = Guid.NewGuid().ToString();
var container = blobClient.GetContainerReference("videos");
var blob = container.GetBlockBlobReference(imageId);
blob.UploadFromStreamAsync(videoStream);
return imageId;
}

Answer 1

IFormFile causes issues because the model binder can only do its thing once the request body has been entirely spooled into memory, which if you have a large upload, could mean using up many gigabytes of RAM or potentially maxing out your RAM utilization entirely.
To buffer the upload, you have to work with the request stream directly, which means turning off model binding entirely on the action. That means you cannot get anything from the action params.
The request body stream will be encoded as multipart/form-data, so you will have to manually parse this into its constituent parts, and bind the data to your entity/model directly, and then read the file part in a buffered way, passing the blocks you read on to your Azure blob storage piece by piece. Microsoft has an example of doing a buffered upload. However, it writes the upload file to disk. Getting it into Azure blob storage is on you.