Added .NET Amazon SDK to my project, and was able to upload images to Amazon S3 with no problems, both on my local server and AppHarbor.
Then I added this line to set the expiration header on upload to S3:
request.AddHeader("Expires", DateTime.Now.AddYears(10).ToString("r"));
This works just fine from my local server, correctly setting the Expires header on S3.
But when I push this code to AppHarbor, I get the following build error:
error CS1061: 'Amazon.S3.Model.PutObjectRequest' does not contain a definition for
'AddHeader' and no extension method 'AddHeader' accepting a first argument of type
'Amazon.S3.Model.PutObjectRequest' could be found (are you missing a using directive or
an assembly reference?)
Thanks very much for your help!