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GitHub User: justinwiley
One thing that caused me some consternation: a misnamed keyfile.
When you create the keypair at Amazon, the name listed on amazon must match the filename locally.
Also, Ryan removes the .pem extension, from gsg-keypair...and Rubber does not tack .pem onto what you define in rubbery.yml.
So in short, make sure the key files names match everywhere.