nil object exception in stripped-down upload example

[irons]

I'm trying to figure out how to upload a file to S3 with the v2 API and ruby 2.1.5, and seeing a surprising degree of resistance. Is this expected to work?

#!/usr/bin/env ruby

require 'aws-sdk'

credential = Aws::Credentials.new('…', '…')
s3 = Aws::S3::Client.new(credentials: credential, region: "us-west-2")
test_object = Aws::S3::Object.new("existing-bucket-name", "test-filename", {region: "us-west-2"})
result = test_object.upload_file("/path/to/test/upload.txt")

Here's how it blows up:

/Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/signers/s3.rb:43:in `sign': undefined method `session_token' for nil:NilClass (NoMethodError)
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/signers/s3.rb:27:in `sign'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_request_signer.rb:45:in `apply_v2_signature'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_request_signer.rb:29:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/xml/error_handler.rb:8:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_request_signer.rb:123:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_redirects.rb:15:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/retry_errors.rb:88:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_md5s.rb:33:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_expect_100_continue.rb:21:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_bucket_dns.rb:31:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/rest_body_handler.rb:9:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/user_agent.rb:12:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/plugins/restful_bindings.rb:13:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/plugins/endpoint.rb:35:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/plugins/param_validation.rb:22:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/plugins/raise_response_errors.rb:14:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/s3_sse_cpk.rb:18:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/plugins/param_conversion.rb:22:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/aws-sdk-core/plugins/response_paging.rb:10:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/plugins/response_target.rb:18:in `call'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/request.rb:70:in `send_request'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-core-2.0.24/lib/seahorse/client/base.rb:216:in `block (2 levels) in define_operation_methods'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-resources-2.0.24/lib/aws-sdk-resources/services/s3/file_uploader.rb:42:in `block in put_object'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-resources-2.0.24/lib/aws-sdk-resources/services/s3/file_uploader.rb:49:in `open_file'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-resources-2.0.24/lib/aws-sdk-resources/services/s3/file_uploader.rb:41:in `put_object'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-resources-2.0.24/lib/aws-sdk-resources/services/s3/file_uploader.rb:34:in `upload'
    from /Users/irons/.rbenv/versions/2.1.5/lib/ruby/gems/2.1.0/gems/aws-sdk-resources-2.0.24/lib/aws-sdk-resources/services/s3/object.rb:102:in `upload_file'
    from ./upload-test.rb:8:in `<main>'

I'm not finding any help in the API documentation for dealing with this problem. I don't know how I managed to misjudge the difficulty of uploading a file by an order of magnitude, but it feels like a feat.

[trevorrowe]

You are very close. You've constructed an API client, but you did not pass this client to the S3 object.

s3 = Aws::S3::Client.new(credentials: credential, region: "us-west-2")
test_object = Aws::S3::Object.new("existing-bucket-name", "test-filename", client: s3)
result = test_object.upload_file("/path/to/test/upload.txt")

That said, I would recommend using the Aws::S3::Resource interface from the start.

s3 = Aws::S3::Resource.new(region:'us-west-2', credentials: credentials)
result = s3.bucket('existing-bucket-name').object('key').upload_file('/path/to/file.txt')

Also, you can skip creating the credentials object, if you are going to use static credentials. You can reduce your original example to the following:

s3 = Aws::S3::Resource.new(region:'us-west-2', access_key_id:'...', secret_access_key: '...')
result = s3.bucket('existing-bucket-name').object('key').upload_file('/path/to/file.txt')

Lastly, I also would recommend never putting static credentials in code. If you are loading them from a file outside version control, that is fine. If not, I would recommend moving them to the shared credentials file. If you create a file at ~/.aws/credentials that looks like this:

[default]
aws_access_key_id =...
aws_secret_access_key=...

[alternate-profile]
aws_access_key_id=...
aws_secret_access_key=...

Then the Ruby SDK will automatically load credentials for you from the default profile. You can also specify a :profile option with the name of what credentials to use, e.g. profile: 'aternate-profile'. Using shared credentials you can reduce your constructor to:

s3 = Aws::S3::Resource.new(region:'us-west-2')

[trevorrowe]

I just pushed a fix that will also improve the error message you receive. It will clearly state that you are calling without credentials instead of no method error on nil. Thanks for reporting the issue. Please feel free to re-open if you continue having issues.