aws_sts_ruby.rb

#!/usr/bin/env ruby

require 'aws-sdk'

sts = Aws::STS::Client.new(
  region: 'us-east-1',
  access_key_id: "<insert access key id>",
  secret_access_key: "<secret>"
)

cred = sts.get_session_token({
  :serial_number=> "<Insert Serial Number of MFA Devise, ex: arn:aws:iam::1234567890:mfa/someuser@example.com>",
  :token_code => "<insert mfa token>",
  :duration_seconds=>3600
})

puts "Access Key ID: " + cred.credentials.access_key_id
puts "Secret Access Key: " + cred.credentials.secret_access_key
puts "Session Token: " + cred.credentials.session_token