class Aws::InstanceProfileCredentials
An auto-refreshing credential provider that loads credentials from EC2 instances.
instance_credentials = Aws::InstanceProfileCredentials.new ec2 = Aws::EC2::Client.new(credentials: instance_credentials)
Constants
- METADATA_PATH_BASE
Path base for GET request for profile and credentials @api private
- METADATA_TOKEN_PATH
Path for PUT request for token @api private
- NETWORK_ERRORS
These are the errors we trap when attempting to talk to the instance metadata service. Any of these imply the service is not present, no responding or some other non-recoverable error. @api private
Attributes
@return [Integer] Number of times to retry when retrieving credentials
from the instance metadata service. Defaults to 0 when resolving from the default credential chain ({Aws::CredentialProviderChain}).
Public Class Methods
@param [Hash] options @option options [Integer] :retries (1) Number of times to retry
when retrieving credentials.
@option options [String] :endpoint (‘169.254.169.254’) The IMDS
endpoint. This option has precedence over the :endpoint_mode.
@option options [String] :endpoint_mode (‘IPv4’) The endpoint mode for
the instance metadata service. This is either 'IPv4' ('169.254.169.254') or 'IPv6' ('[fd00:ec2::254]').
@option options [Boolean] :disable_imds_v1 (false) Disable the use of the
legacy EC2 Metadata Service v1.
@option options [String] :ip_address (‘169.254.169.254’) Deprecated. Use
:endpoint instead. The IP address for the endpoint.
@option options [Integer] :port (80) @option options [Float] :http_open_timeout (1) @option options [Float] :http_read_timeout (1) @option options [Numeric, Proc] :delay By default, failures are retried
with exponential back-off, i.e. `sleep(1.2 ** num_failures)`. You can pass a number of seconds to sleep between failed attempts, or a Proc that accepts the number of failures.
@option options [IO] :http_debug_output (nil) HTTP wire
traces are sent to this object. You can specify something like $stdout.
@option options [Integer] :token_ttl Time-to-Live in seconds for EC2
Metadata Token used for fetching Metadata Profile Credentials, defaults to 21600 seconds
@option options [Callable] before_refresh Proc called before
credentials are refreshed. `before_refresh` is called with an instance of this object when AWS credentials are required and need to be refreshed.
Aws::RefreshingCredentials::new
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 77 def initialize(options = {}) @retries = options[:retries] || 1 endpoint_mode = resolve_endpoint_mode(options) @endpoint = resolve_endpoint(options, endpoint_mode) @port = options[:port] || 80 @disable_imds_v1 = resolve_disable_v1(options) # Flag for if v2 flow fails, skip future attempts @imds_v1_fallback = false @http_open_timeout = options[:http_open_timeout] || 1 @http_read_timeout = options[:http_read_timeout] || 1 @http_debug_output = options[:http_debug_output] @backoff = backoff(options[:backoff]) @token_ttl = options[:token_ttl] || 21_600 @token = nil @no_refresh_until = nil @async_refresh = false super end
Private Instance Methods
token is optional - if nil, uses v1 (insecure) flow
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 243 def _get_credentials(conn, token) metadata = http_get(conn, METADATA_PATH_BASE, token) profile_name = metadata.lines.first.strip http_get(conn, METADATA_PATH_BASE + profile_name, token) rescue TokenExpiredError # Token has expired, reset it # The next retry should fetch it @token = nil @imds_v1_fallback = false raise Non200Response end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 259 def _metadata_disabled? ENV.fetch('AWS_EC2_METADATA_DISABLED', 'false').downcase == 'true' end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 141 def backoff(backoff) case backoff when Proc then backoff when Numeric then ->(_) { sleep(backoff) } else ->(num_failures) { Kernel.sleep(1.2**num_failures) } end end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 329 def empty_credentials?(creds) !creds || !creds.access_key_id || creds.access_key_id.empty? end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 225 def fetch_token(conn) retry_errors(NETWORK_ERRORS, max_retries: @retries) do unless token_set? created_time = Time.now token_value, ttl = http_put( conn, METADATA_TOKEN_PATH, @token_ttl ) @token = Token.new(token_value, ttl, created_time) if token_value && ttl end end rescue *NETWORK_ERRORS # token attempt failed, reset token # fallback to non-token mode @token = nil @imds_v1_fallback = true end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 197 def get_credentials # Retry loading credentials a configurable number of times if # the instance metadata service is not responding. if _metadata_disabled? '{}' else begin retry_errors(NETWORK_ERRORS, max_retries: @retries) do open_connection do |conn| # attempt to fetch token to start secure flow first # and rescue to failover fetch_token(conn) unless @imds_v1_fallback token = @token.value if token_set? # disable insecure flow if we couldn't get token # and imds v1 is disabled raise TokenRetrivalError if token.nil? && @disable_imds_v1 _get_credentials(conn, token) end end rescue => e warn("Error retrieving instance profile credentials: #{e}") '{}' end end end
GET request fetch profile and credentials
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 274 def http_get(connection, path, token = nil) headers = { 'User-Agent' => "aws-sdk-ruby3/#{CORE_GEM_VERSION}" } headers['x-aws-ec2-metadata-token'] = token if token response = connection.request(Net::HTTP::Get.new(path, headers)) case response.code.to_i when 200 response.body when 401 raise TokenExpiredError else raise Non200Response end end
PUT request fetch token with ttl
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 290 def http_put(connection, path, ttl) headers = { 'User-Agent' => "aws-sdk-ruby3/#{CORE_GEM_VERSION}", 'x-aws-ec2-metadata-token-ttl-seconds' => ttl.to_s } response = connection.request(Net::HTTP::Put.new(path, headers)) case response.code.to_i when 200 [ response.body, response.header['x-aws-ec2-metadata-token-ttl-seconds'].to_i ] when 400 raise TokenRetrivalError else raise Non200Response end end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 263 def open_connection uri = URI.parse(@endpoint) http = Net::HTTP.new(uri.hostname || @endpoint, uri.port || @port) http.open_timeout = @http_open_timeout http.read_timeout = @http_read_timeout http.set_debug_output(@http_debug_output) if @http_debug_output http.start yield(http).tap { http.finish } end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 149 def refresh if @no_refresh_until && @no_refresh_until > Time.now warn_expired_credentials return end # Retry loading credentials up to 3 times is the instance metadata # service is responding but is returning invalid JSON documents # in response to the GET profile credentials call. begin retry_errors([Aws::Json::ParseError], max_retries: 3) do c = Aws::Json.load(get_credentials.to_s) if empty_credentials?(@credentials) @credentials = Credentials.new( c['AccessKeyId'], c['SecretAccessKey'], c['Token'] ) @expiration = c['Expiration'] ? Time.iso8601(c['Expiration']) : nil if @expiration && @expiration < Time.now @no_refresh_until = Time.now + refresh_offset warn_expired_credentials end else # credentials are already set, update them only if the new ones are not empty if !c['AccessKeyId'] || c['AccessKeyId'].empty? # error getting new credentials @no_refresh_until = Time.now + refresh_offset warn_expired_credentials else @credentials = Credentials.new( c['AccessKeyId'], c['SecretAccessKey'], c['Token'] ) @expiration = c['Expiration'] ? Time.iso8601(c['Expiration']) : nil if @expiration && @expiration < Time.now @no_refresh_until = Time.now + refresh_offset warn_expired_credentials end end end end rescue Aws::Json::ParseError raise Aws::Errors::MetadataParserError end end
Compute an offset for refresh with jitter
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 334 def refresh_offset 300 + rand(0..60) end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 131 def resolve_disable_v1(options) value = options[:disable_imds_v1] value ||= ENV['AWS_EC2_METADATA_V1_DISABLED'] value ||= Aws.shared_config.ec2_metadata_v1_disabled( profile: options[:profile] ) value = value.to_s.downcase if value Aws::Util.str_2_bool(value) || false end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 112 def resolve_endpoint(options, endpoint_mode) value = options[:endpoint] || options[:ip_address] value ||= ENV['AWS_EC2_METADATA_SERVICE_ENDPOINT'] value ||= Aws.shared_config.ec2_metadata_service_endpoint( profile: options[:profile] ) return value if value case endpoint_mode.downcase when 'ipv4' then 'http://169.254.169.254' when 'ipv6' then 'http://[fd00:ec2::254]' else raise ArgumentError, ':endpoint_mode is not valid, expected IPv4 or IPv6, '\ "got: #{endpoint_mode}" end end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 103 def resolve_endpoint_mode(options) value = options[:endpoint_mode] value ||= ENV['AWS_EC2_METADATA_SERVICE_ENDPOINT_MODE'] value ||= Aws.shared_config.ec2_metadata_service_endpoint_mode( profile: options[:profile] ) value || 'IPv4' end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 309 def retry_errors(error_classes, options = {}, &_block) max_retries = options[:max_retries] retries = 0 begin yield rescue *error_classes raise unless retries < max_retries @backoff.call(retries) retries += 1 retry end end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 255 def token_set? @token && !@token.expired? end
# File lib/aws-sdk-core/instance_profile_credentials.rb, line 323 def warn_expired_credentials warn("Attempting credential expiration extension due to a credential "\ "service availability issue. A refresh of these credentials "\ "will be attempted again in 5 minutes.") end