Ruby on Rails direct upload to S3 without paperclip

        file = "public/to_be_uploaded.txt"
        file_path = Rails.root.join(file)
        local_file = File.open(local_file_path)
        
        bucket_name = "BUCKET_NAME"
        s3 = AWS::S3.new(
            :access_key_id     => "KEY", 
            :secret_access_key => "SECRET_ACCESS_KEY",
            :s3_endpoint => "S3_ENDPOINT"
        )
        
        ## Define upload file name ##
        key = File.basename("uploaded_on_s3.txt")
        s3.buckets[bucket_name].objects[key].write(:file => local_file)