Lincoln D. Stein > VM-EC2-1.23 > VM::EC2::Instance::Metadata

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NAME ^

VM::EC2::Instance::Metadata - Object describing the metadata of a running instance

SYNOPSIS ^

 # For use within a running EC2 instance only!

 use VM::EC2::Instance::Metadata;
 my $meta = VM::EC2::Instance::Metadata->new;

 # alternatively...
 my $meta = VM::EC2->instance_metadata;
 my $meta = $instance->metadata;

 # image information
 $image_id  = $meta->imageId;
 $index     = $meta->imageLaunchIndex;
 $path      = $meta->amiManifestPath;
 $location  = $meta->imageLocation;    # same as previous
 @ancestors = $meta->ancestorAmiIds;
 @ancestors = $meta->imageAncestorIds; # same as previous
 @codes     = $meta->productCodes;

 # launch and runtime information
 $inst_id   = $meta->instanceId;
 $kern_id   = $meta->kernelId;
 $rd_id     = $meta->ramdiskId;
 $res_id    = $meta->reservationId;
 $type      = $meta->instanceType;
 $zone      = $meta->availabilityZone;
 $userdata  = $meta->userData;
 @groups    = $meta->securityGroups;
 @keys      = $meta->publicKeys;
 $block_dev = $meta->blockDeviceMapping; # a hashref

 # Network information
 $priv_name = $meta->localHostname;
 $priv_name = $meta->privateDnsName;   # same as previous
 $priv_ip   = $meta->localIpv4;
 $priv_ip   = $meta->privateIpAddress;
 $mac       = $meta->mac;
 $pub_name  = $meta->publicHostname;
 $pub_name  = $meta->dnsName;          # same as previous
 $pub_ip    = $meta->publicIpv4;
 $pub_ip    = $meta->ipAddress;
 $interfaces= $meta->interfaces;       # a hashref

 # IAM information
 $iam_info   = $metadata->iam_info;         # a hashref
 $iam_role   = $metadata->iam_role;         # name of the role
 $credentials= $metadata->iam_credentials;  # VM::EC2::Security::Credentials object

 # Undocumented fields
 $action    = $meta->instanceAction;
 $profile   = $meta->profile;

DESCRIPTION ^

This is an interface to the metadata that is provided to a running instance via the http://169.254.169.254/latest URL, as described in http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/index.html?instancedata-data-categories.html.

Each metadata object caches its values, so there is no overhead in calling a method repeatedly. Methods return scalar values, lists and hashrefs as appropriate.

The methods from this class should only be called within the context of a running EC2 instance. Attempts to call outside of this context will result in long delays as the module attempts to connect to an invalid hostname.

METHODS ^

$meta = VM::EC2::Instance::Metadata->new()

$meta = $ec2->instance_metadata()

$meta = $instance->metadata()

You can create a new metadata object either using this class's new() constructor, or by calling an VM::EC2 object's instance_metadata() method, or by calling a VM::EC2::Instance object's metadata () method.

Methods that return scalar values

The following methods all return single-valued results:

Image information:
 imageId                -- ID of AMI used to launch this instance
 imageLaunchIndex       -- This index's launch index. If four instances
                           were launched by one $image->run_instances()
                           call, they will be numbered from 0 to 3.
 amiManifestPath        -- S3 path to the image
 imageLocation          -- Same as amiManifestPath(), for consistency with
                           VM::EC2::Image
Launch and runtime information:
 instanceId             -- ID of this instance
 kernelId               -- ID of this instance's kernel.
 ramdiskId              -- This instance's ramdisk ID
 reservationId          -- This instance's reservation ID
 instanceType           -- Machine type, e.g. "m1.small"
 availabilityZone       -- This instance's availability zone.
 region                 -- This instance's region.
 endpoint               -- This instance's endpoint.
 userData               -- User data passed at launch time.
Network information:
 localHostname          -- The instance hostname corresponding to its
                           internal EC2 IP address.
 privateDnsName         -- Same as localHostname(), for consistency with
                           VM::EC2::Instance
 localIpv4              -- The instance IP address on the internal EC2 network.
 privateIpAddress       -- Same as localIpv4(), for consistency with 
                           VM::EC2::Instance.
 mac                    -- This instance's MAC (ethernet) address.
 publicHostname         -- This instance's public hostname.
 dnsName                -- Same as publicHostname() for consistency with
                           VM::EC2::Instance.
 publicIpv4             -- This instance's public IP address.
 ipAddress              -- Same as publicIpv4() for consistency with
                           VM::EC2::Instance.
IAM information

These routines return information about the instance's IAM role, if any. These calls also provide a temporary security credentials for making EC2 calls, as described here: http://docs.amazonwebservices.com/AWSEC2/latest/UserGuide/UsingIAM.html.

Note that these routines require installation of the perl JSON module, and will cause a fatal error if this module cannot be loaded.

 iam_info               -- Returns a hash containing the fields 'LastUpdated',
                           'InstanceProfileArn', and 'InstanceProfileId'. These
                           provide information about the instance's IAM role.
 iam_role               -- Returns the IAM role name for the currently running
                           instance.
 iam_credentials        -- Returns a VM::EC2::Security::Credentials object that can
                           be passed to VM::EC2->new(-security_token=>$credentials).
Unknown information:
 profile                -- An undocumented field that contains the virtualization
                           type in the form "default-paravirtual".
 instanceAction         -- Undocumented metadata field named "instance-action"

Methods that return lists

The following methods all return lists.

Image information
 ancestorAmiIds        -- List of  AMIs from which the current one was derived
 imageAncestorIds      -- Same as ancestorAmiIds() but easier to read.
 productCodes          -- List of product codes applying to the image from which
                          this instance was launched.
Launch and runtime information
 securityGroups        -- List of security groups to which this instance is assigned.
                          For non-VPC instances, this will be the security group
                          name. For VPC instances, this will be the security group ID.
 publicKeys            -- List of public key pair names attached to this instance.

Methods that return a hashref

The following methods return a hashref for representing complex data structures:

$devices = $meta->blockDeviceMapping

This returns a hashref in which the keys are the names of instance block devices, such as "/dev/sda1", and the values are the EC2 virtual machine names. For example:

 x $meta->blockDeviceMapping
 0  HASH(0x9b4f2f8)
   '/dev/sda1' => 'root'
   '/dev/sda2' => 'ephemeral0'
   '/dev/sdg' => 'ebs1'
   '/dev/sdh' => 'ebs9'
   '/dev/sdi' => 'ebs10'
   'sda3' => 'swap'

For reasons that are not entirely clear, the swap device is reported as "sda3" rather than as "/dev/sda3".

$interfaces = $meta->interfaces

Returns a mapping of all virtual ethernet devices owned by this instance. This is primarily useful for VPC instances, which can have more than one device. The hash keys are the MAC addresses of each ethernet device, and the values are hashes that have the following keys:

 mac
 localHostname
 localIpv4s        (an array ref)
 publicIpv4s       (an array ref)
 securityGroupIds  (an array ref)
 subnetId
 subnetIpv4CidrBlock
 vpcId
 vpcIpv4CidrBlock

For example:

                                                                                                                                     D
 x $meta->interfaces        
 0 HASH(0x9b4f518)
   '12:31:38:01:b8:97' => HASH(0x9eaa090)
      'localHostname' => 'domU-12-31-38-01-B8-97.compute-1.internal'
      'localIpv4s' => ARRAY(0x9b4f8a8)
         0  '10.253.191.101'
      'mac' => '12:31:38:01:b8:97'
      'publicIpv4s' => ARRAY(0x9ea9e40)
         0  '184.73.241.210'
      'securityGroupIds' => ARRAY(0x9eaa490)
           empty array
      'subnetId' => undef
      'subnetIpv4CidrBlock' => undef
      'vpcId' => undef
      'vpcIpv4CidrBlock' => undef

SEE ALSO ^

VM::EC2 VM::EC2::Generic VM::EC2::BlockDevice VM::EC2::State::Reason VM::EC2::State VM::EC2::Instance VM::EC2::Tag

AUTHOR ^

Lincoln Stein <lincoln.stein@gmail.com>.

Copyright (c) 2011 Ontario Institute for Cancer Research

This package and its accompanying libraries is free software; you can redistribute it and/or modify it under the terms of the GPL (either version 1, or at your option, any later version) or the Artistic License 2.0. Refer to LICENSE for the full license text. In addition, please see DISCLAIMER.txt for disclaimers of warranty.

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