Class: Aws::EC2Metadata

Inherits:
Object
  • Object
show all
Defined in:
lib/aws-sdk-core/ec2_metadata.rb

Overview

A client that can query version 2 of the EC2 Instance Metadata

Defined Under Namespace

Classes: MetadataNotFoundError, RequestForbiddenError, Token, TokenExpiredError, TokenRetrievalError

Constant Summary collapse

METADATA_TOKEN_PATH =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future.

Path for PUT request for token

'/latest/api/token'.freeze

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ EC2Metadata

Note:

Customers using containers may need to increase their hop limit to access IMDSv2.

Creates a client that can query version 2 of the EC2 Instance Metadata

service (IMDS).

Parameters:

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :token_ttl (Integer) — default: 21600 —

    The session token’s TTL, defaulting to 6 hours.

  • :retries (Integer) — default: 3 —

    The number of retries for failed requests.

  • :endpoint (String) — default: 169.254.169.254 —

    The IMDS endpoint.

  • :port (Integer) — default: 80 —

    The IMDS endpoint port.

  • :http_open_timeout (Integer) — default: 1 —

    The number of seconds to wait for the connection to open.

  • :http_read_timeout (Integer) — default: 1 —

    The number of seconds for one chunk of data to be read.

  • :http_debug_output (IO) —

    An output stream for debugging. Do not use this in production.

  • :backoff (Integer, Proc) —

    A backoff used for retryable requests. When given an Integer, it sleeps that amount. When given a Proc, it is called with the current number of failed retries.

See Also:



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# File 'lib/aws-sdk-core/ec2_metadata.rb', line 53

def initialize(options = {})
  @token_ttl = options[:token_ttl] || 21_600
  @retries = options[:retries] || 3
  @backoff = backoff(options[:backoff])

  @endpoint = options[:endpoint] || '169.254.169.254'
  @port = options[:port] || 80

  @http_open_timeout = options[:http_open_timeout] || 1
  @http_read_timeout = options[:http_read_timeout] || 1
  @http_debug_output = options[:http_debug_output]

  @token = nil
  @mutex = Mutex.new
end

Instance Method Details

#get(path) ⇒ Object

Fetches a given metadata category using a String path, and returns the

result as a String. A path starts with the API version (usually
"/latest/"). See the instance data categories for possible paths.

Examples:

Fetching the instance ID


ec2_metadata = Aws::EC2Metadata.new
ec2_metadata.get('/latest/meta-data/instance-id')
=> "i-023a25f10a73a0f79"

Fetching and parsing JSON meta-data


require 'json'
data = ec2_metadata.get('/latest/dynamic/instance-identity/document')
JSON.parse(data)
=> {"accountId"=>"012345678912", ... }

Fetching and parsing directory listings


listing = ec2_metadata.get('/latest/meta-data')
listing.split(10.chr)
=> ["ami-id", "ami-launch-index", ...]

Parameters:

  • path (String) —

    The full path to the metadata.

See Also:



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# File 'lib/aws-sdk-core/ec2_metadata.rb', line 105

def get(path)
  retry_errors(max_retries: @retries) do
    @mutex.synchronize do
      fetch_token unless @token && !@token.expired?
    end

    open_connection do |conn|
      http_get(conn, path, @token.value)
    end
  end
end