AWS – Amazon Web Services client library for Ruby

Simply provide your amazon access key and amazon secret key to start making calls:

client = AWS::EC2::Client.new(
    :access_key_id => ACCESS_KEY_ID, 
    :secret_access_key => SECRET_ACCESS_KEY
)
client.describe_regions

=> {"regionInfo"=>{
        "item"=>[
            {"regionName"=>"eu-west-1", "regionEndpoint"=>"eu-west-1.ec2.amazonaws.com"}, 
            {"regionName"=>"us-east-1", "regionEndpoint"=>"us-east-1.ec2.amazonaws.com"}
        ]
    },
    "requestId"=>"c6b5e7b4-421d-4484-932c-dcf32e66a2ab", 
    "xmlns"=>"http://ec2.amazonaws.com/doc/2009-04-04/"
}

You can also specify a region to make calls in a specific region:

client = AWS::EC2::Client.new(
    :access_key_id => ACCESS_KEY_ID, 
    :secret_access_key => SECRET_ACCESS_KEY, 
    :region => 'eu-west-1'
)
client.describe_availability_zones

=> {"availabilityZoneInfo"=>{

        “item”=>[

            {"zoneName"=>"eu-west-1a", “regionName”=>"eu-west-1", “zoneState”=>"available"}, 

            {"zoneName"=>"eu-west-1b", “regionName”=>"eu-west-1", “zoneState”=>"available"}

        ]

    }, 

    “requestId”=>"ed31f360-bb07-4417-b976-5f5bd1740e6e", 

    “xmlns”=>"http://ec2.amazonaws.com/doc/2009-04-04/"

}