Get image from URL and upload to Amazon S3 - asp.net

Question

I'd like to load an image directly from a URL but without saving it on the server, I want to upload it directly from memory to Amazon S3 server.
This is my code:
Dim wc As New WebClient
Dim fileStream As IO.Stream = wc.OpenRead("http://www.domain.com/image.jpg")
Dim request As New PutObjectRequest()
request.BucketName = "mybucket"
request.Key = "file.jpg"
request.InputStream = fileStream
client.PutObject(request)
The Amazon API gives me the error "Could not determine content length". The stream fileStream ends up as "System.Net.ConnectStream" which I'm not sure if it's correct.
The exact same code works with files from the HttpPostedFile but I need to use it in this way now.
Any ideas how I can convert the stream to become what Amazon API is expecting (with the length intact)?

Answer 1

I had the same problem when I'm using the GetObjectResponse() method and its propertie ResponseStream to copy a file from a folder to another in same bucket. I noted that the AWS SDK (2.3.45) have some faults like a another method called WriteResponseStreamToFile in GetObjectResponse() that simply doesn't work. These lacks of functions needs some workarounds.
I solved the problem openning the file in array of bytes and putting it in a MemoryStream object.
Try this (C# code)
WebClient wc = new WebClient();
Stream fileStream = wc.OpenRead("http://www.domain.com/image.jpg");
byte[] fileBytes = fileStream.ToArrayBytes();
PutObjectRequest request = new PutObjectRequest();
request.BucketName = "mybucket";
request.Key = "file.jpg";
request.InputStream = new MemoryStream(fileBytes);
client.PutObject(request);
The extesion method
public static byte[] ToArrayBytes(this Stream input)
{
byte[] buffer = new byte[16 * 1024];
using (MemoryStream ms = new MemoryStream())
{
int read;
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}
return ms.ToArray();
}
}
You can also create a MemoryStream without an array of bytes. But after the first PutObject in S3, the MemoryStream will be discarted. If you need to put others objects, I recommend the first option
WebClient wc = new WebClient();
Stream fileStream = wc.OpenRead("http://www.domain.com/image.jpg");
MemoryStream fileMemoryStream = fileStream.ToMemoryStream();
PutObjectRequest request = new PutObjectRequest();
request.BucketName = "mybucket";
request.Key = "file.jpg";
request.InputStream = fileMemoryStream ;
client.PutObject(request);
The extesion method
public static MemoryStream ToMemoryStream(this Stream input)
{
byte[] buffer = new byte[16 * 1024];
int read;
MemoryStream ms = new MemoryStream();
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}
return ms;
}

Answer 2

I had the same problem in a similar scenario.
The reason for the error is that to upload an object the SDK needs to know the whole content length that is going to be uploaded. To be able to obtain stream length it must be seekable, but the stream returned from WebClient is not. To indicate the expected length set Headers.ContentLength in PutObjectRequest. The SDK will use this value if it cannot determine length from the stream object.
To make your code work, obtain content length from the response headers returned by the call made by WebClient. Then set PutObjectRequest.Headers.ContentLength. Of course this relies on the server returned content length value.
Dim wc As New WebClient
Dim fileStream As IO.Stream = wc.OpenRead("http://www.example.com/image.jpg")
Dim contentLength As Long = Long.Parse(client.ResponseHeaders("Content-Length"))
Dim request As New PutObjectRequest()
request.BucketName = "mybucket"
request.Key = "file.jpg"
request.InputStream = fileStream
request.Headers.ContentLength = contentLength
client.PutObject(request)

Answer 3

I came up with a solution that uses UploadPart when the length is not available by any other means, plus this does not load the entire file into memory.
if (args.DocumentContents.CanSeek)
{
PutObjectRequest r = new PutObjectRequest();
r.InputStream = args.DocumentContents;
r.BucketName = s3Id.BucketName;
r.Key = s3Id.ObjectKey;
foreach (var item in args.CustomData)
{
r.Metadata[item.Key] = item.Value;
}
await S3Client.PutObjectAsync(r);
}
else
{
// if stream does not allow seeking, S3 client will throw error:
// Amazon.S3.AmazonS3Exception : Could not determine content length
// as a work around, if cannot use length property, will chunk
// file into sections and use UploadPart, so do not have to load
// entire file into memory as a single MemoryStream.
var r = new InitiateMultipartUploadRequest();
r.BucketName = s3Id.BucketName;
r.Key = s3Id.ObjectKey;
foreach (var item in args.CustomData)
{
r.Metadata[item.Key] = item.Value;
}
var multipartResponse = await S3Client.InitiateMultipartUploadAsync(r);
try
{
var completeRequest = new CompleteMultipartUploadRequest
{
UploadId = multipartResponse.UploadId,
BucketName = s3Id.BucketName,
Key = s3Id.ObjectKey,
};
// just using this size, because it is the max for Azure File Share, but it could be any size
// for S3, even a configured value
const int blockSize = 4194304;
// BinaryReader gives us access to ReadBytes
using (var reader = new BinaryReader(args.DocumentContents))
{
var partCounter = 1;
while (true)
{
byte[] buffer = reader.ReadBytes(blockSize);
if (buffer.Length == 0)
break;
using (MemoryStream uploadChunk = new MemoryStream(buffer))
{
uploadChunk.Position = 0;
var uploadRequest = new UploadPartRequest
{
BucketName = s3Id.BucketName,
Key = s3Id.ObjectKey,
UploadId = multipartResponse.UploadId,
PartNumber = partCounter,
InputStream = uploadChunk,
};
// could call UploadPart on multiple threads, instead of using await, but that would
// cause more data to be loaded into memory, which might be too much
var part2Task = await S3Client.UploadPartAsync(uploadRequest);
completeRequest.AddPartETags(part2Task);
}
partCounter++;
}
var completeResponse = await S3Client.CompleteMultipartUploadAsync(completeRequest);
}
}
catch
{
await S3Client.AbortMultipartUploadAsync(s3Id.BucketName, s3Id.ObjectKey
, multipartResponse.UploadId);
throw;
}
}