VM::EC2::Instance::Metadata - Object describing the metadata of a
    running instance
 # 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;
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.
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.
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"
    
   
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.
    
   
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
    
   
VM::EC2 VM::EC2::Generic VM::EC2::BlockDevice
    VM::EC2::State::Reason VM::EC2::State VM::EC2::Instance VM::EC2::Tag
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.