AuthUsingTempFederationTokenRuby.md

Making requests using federated user temporary credentials - AWS SDK for Ruby

You can provide temporary security credentials for your federated users and applications so that they can send authenticated requests to access your AWS resources. When requesting temporary credentials from the IAM service, you must provide a user name and an IAM policy that describes the resource permissions that you want to grant. By default, the session duration is one hour. However, if you are requesting temporary credentials using IAM user credentials, you can explicitly set a different duration value when requesting the temporary security credentials for federated users and applications. For information about temporary security credentials for your federated users and applications, see Making requests.

Note For added security when you request temporary security credentials for federated users and applications, you might want to use a dedicated IAM user with only the necessary access permissions. The temporary user you create can never get more permissions than the IAM user who requested the temporary security credentials. For more information, see AWS Identity and Access Management FAQs .

Example The following Ruby code example allows a federated user with a limited set of permissions to lists keys in the specified bucket.

require 'aws-sdk-s3'
require 'aws-sdk-iam'
require 'json'

# Checks to see whether a user exists in IAM; otherwise,
# creates the user.
#
# @param iam [Aws::IAM::Client] An initialized IAM client.
# @param user_name [String] The user's name.
# @return [Aws::IAM::Types::User] The existing or new user.
# @example
#   iam = Aws::IAM::Client.new(region: 'us-east-1')
#   user = get_user(iam, 'my-user')
#   exit 1 unless user.user_name
#   puts "User's name: #{user.user_name}"
def get_user(iam, user_name)
  puts "Checking for a user with the name '#{user_name}'..."
  response = iam.get_user(user_name: user_name)
  puts "A user with the name '#{user_name}' already exists."
  return response.user
# If the user doesn't exist, create them.
rescue Aws::IAM::Errors::NoSuchEntity
  puts "A user with the name '#{user_name}' doesn't exist. Creating this user..."
  response = iam.create_user(user_name: user_name)
  iam.wait_until(:user_exists, user_name: user_name)
  puts "Created user with the name '#{user_name}'."
  return response.user
rescue StandardError => e
  puts "Error while accessing or creating the user named '#{user_name}': #{e.message}"
end

# Gets temporary AWS credentials for an IAM user with the specified permissions.
#
# @param sts [Aws::STS::Client] An initialized AWS STS client.
# @param duration_seconds [Integer] The number of seconds for valid credentials.
# @param user_name [String] The user's name.
# @param policy [Hash] The access policy.
# @return [Aws::STS::Types::Credentials] AWS credentials for API authentication.
# @example
#   sts = Aws::STS::Client.new(region: 'us-east-1')
#   credentials = get_temporary_credentials(sts, duration_seconds, user_name, 
#     {
#       'Version' => '2012-10-17',
#       'Statement' => [
#         'Sid' => 'Stmt1',
#         'Effect' => 'Allow',
#         'Action' => 's3:ListBucket',
#         'Resource' => 'arn:aws:s3:::doc-example-bucket'
#       ]
#     }
#   )
#   exit 1 unless credentials.access_key_id
#   puts "Access key ID: #{credentials.access_key_id}"
def get_temporary_credentials(sts, duration_seconds, user_name, policy)
  response = sts.get_federation_token(
    duration_seconds: duration_seconds,
    name: user_name,
    policy: policy.to_json
  )
  return response.credentials
rescue StandardError => e
  puts "Error while getting federation token: #{e.message}"
end

# Lists the keys and ETags for the objects in an Amazon S3 bucket.
#
# @param s3_client [Aws::S3::Client] An initialized Amazon S3 client.
# @param bucket_name [String] The bucket's name.
# @return [Boolean] true if the objects were listed; otherwise, false.
# @example
#   s3_client = Aws::S3::Client.new(region: 'us-east-1')
#   exit 1 unless list_objects_in_bucket?(s3_client, 'doc-example-bucket')
def list_objects_in_bucket?(s3_client, bucket_name)
  puts "Accessing the contents of the bucket named '#{bucket_name}'..."
  response = s3_client.list_objects_v2(
    bucket: bucket_name,
    max_keys: 50
  )

  if response.count.positive?
    puts "Contents of the bucket named '#{bucket_name}' (first 50 objects):"
    puts 'Name => ETag'
    response.contents.each do |obj|
      puts "#{obj.key} => #{obj.etag}"
    end
  else
    puts "No objects in the bucket named '#{bucket_name}'."
  end
  return true
rescue StandardError => e
  puts "Error while accessing the bucket named '#{bucket_name}': #{e.message}"
end