AWS S3 upload file with pre-signed URL in .NET

Question

I already search on Internet, but no success.

I'm working with C#/.NET 6 and I "simply" have to upload a file to a AWS S3 bucket using a pre-signed URL.

To generate the pre-signed URL, I use the following code:

private static Uri GetPresignedUrl(IAmazonS3 amazonS3, AwsPresignedUrlOptions awsPresignedUrlOptions)
{
    GetPreSignedUrlRequest request = new()
    {
        BucketName = awsPresignedUrlOptions.BucketName,
        Key = awsPresignedUrlOptions.ResourcePath,
        Verb = awsPresignedUrlOptions.HttpVerb,
        Expires = awsPresignedUrlOptions.Expires,
    };

    return new Uri(amazonS3.GetPreSignedURL(request));
}

After that I do the following:

output = GetPresignedUrl(amazonS3, awsPresignedUrlOptions);

using (FileStream tempInFileStream = new(tempFileName.LocalPath, FileMode.Open))
{
    using (HttpClient httpClient = new())
    {
        StreamContent streamContent = new(tempInFileStream);
        HttpResponseMessage response = await httpClient
            .PutAsync(output, streamContent);

        response.EnsureSuccessStatusCode();
    }
}

but the system does absolutely nothing till the Timeout.

If I use the pre-signed URL I calculate and try a PUT in Postman I obtain the following:

<?xml version="1.0" encoding="UTF-8"?>
<Error>
    <Code>AccessDenied</Code>
    <Message>Access Denied</Message>
    <RequestId>A2F70F25SPEMJF8X</RequestId>
    <HostId>V+pbAWrEeLb/xJvPLvkytLoLUEBhyEWv+IV4H/PSLLKV3rLlF7fIntPUONLaLXIow9gUaTkAF/k=</HostId>
</Error>

Any suggestion?

Thank you.

Answer 1

I spent a lot of time reviewing all the security policies, and the error was right there. If you have the same problem, please check that:

• The user you are using is still active and has a valid access key and secret key.
• The user has the correct permissions to access the S3 bucket (I chose "AmazonS3FullAccess" for my tests).

Regards.