CODEWITHSUNDEEP
c#amazon-web-servicesamazon-s3lambda
Weston Sankey
Weston Sankey

Reputation: 343

AWS Lambda C# Upload Object to S3

I have a Lambda function written in C# that is unsuccessfully attempting to upload an object to an S3 bucket. For testing purposes, I am converting the input string to a byte array and using that as the object contents. My handler function is defined below:

public void FunctionHandler(string input, ILambdaContext context)
{
    IAmazonS3 client = new AmazonS3Client(Amazon.RegionEndpoint.USEast1);

    byte[] bytes = new byte[input.Length * sizeof(char)];
    Buffer.BlockCopy(input.ToCharArray(), 0, bytes, 0, bytes.Length);

    using (MemoryStream ms = new MemoryStream())
    {
        foreach (Byte b in bytes)
        {
            ms.WriteByte(b);
        }

        PutObjectRequest request = new PutObjectRequest()
        {
            BucketName = "BUCKET_NAME",
            Key = "OBJECT_KEY",
            InputStream = ms
        };

        client.PutObjectAsync(request);
    }
}

The function runs without error, but the object is not written to S3. I feel that it might have something to do with the PutObjectAsync method, but I'm not positive. The IAmazonS3 interface includes a PutObject method, but when attempting to use that method I receive the following error:

'IAmazonS3' does not contain a definition for 'PutObject'

What is the best way to upload an object to an S3 bucket in a C# Lambda function?

Upvotes: 5

Views: 9491

Answers (2)

Usama Khalil
Usama Khalil

Reputation: 436

You should apply await with the Async

await client.PutObjectAsync(request);

Upvotes: 2

E.J. Brennan
E.J. Brennan

Reputation: 46839

This is the helper function I use to put S3 objects to S3, from a C# lambda function (and it works). You might be able to use this as a starting point for yours.

Not sure why you are converting your string to bytes, and in C#/Lambda you need to use the PutObjectAsync method, not the PutObject method:

 public static async Task<bool> PutS3Object(string bucket, string key, string content)
        {
            try
            {
                using (var client = new AmazonS3Client(Amazon.RegionEndpoint.USEast1))
                {
                    var request = new PutObjectRequest
                    {
                        BucketName = bucket,
                        Key = key,
                        ContentBody = content
                    };
                    var response = await client.PutObjectAsync(request);
                }
                return true;
            }
            catch (Exception ex)
            {
                Console.WriteLine("Exception in PutS3Object:" + ex.Message);
                return false;
            }
        }

Upvotes: 10

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