Find AWS user by access key

find_aws_user.rb

require 'json'

key_to_find = /.*thing-or-whatever.*/

users = JSON.parse(`aws iam list-users`).fetch('Users')
usernames = users.map { |user|
  user.fetch('UserName')
}

user_secret_keys = Hash[
  usernames.map { |username|
    secret_key_output = `aws iam list-access-keys --user #{username}`
    secret_keys = JSON.parse(secret_key_output).fetch('AccessKeyMetadata')
    [username, secret_keys.map { |sk| sk.fetch('AccessKeyId') }]
  }
]

matching_users = user_secret_keys.select { |user, keys|
  keys.any? { |key|
    key_to_find.match(key)
  }
}

matching_users.each do |username, keys|
  puts username
  matching_keys = keys.select { |key|
    key_to_find.match(key)
  }
  puts "\t#{matching_keys}"
end