NAME¶

VM::EC2 - Perl interface to Amazon EC2, Virtual Private Cloud, Elastic Load Balancing, Autoscaling, and Relational Database services

SYNOPSIS¶

NOTE: For information on AWS's VPC, load balancing, autoscaling and relational databases services, see VM::EC2::VPC, VM::EC2::ELB, VM::EC2::REST::autoscaling, and VM::EC2::REST::relational_database_service

 # set environment variables EC2_ACCESS_KEY, EC2_SECRET_KEY and/or EC2_URL
 # to fill in arguments automatically
 ## IMAGE AND INSTANCE MANAGEMENT
 # get new EC2 object
 my $ec2 = VM::EC2->new(-access_key => 'access key id',
                        -secret_key => 'aws_secret_key',
                        -endpoint   => 'http://ec2.amazonaws.com');
 # fetch an image by its ID
 my $image = $ec2->describe_images('ami-12345');
 # get some information about the image
 my $architecture = $image->architecture;
 my $description  = $image->description;
 my @devices      = $image->blockDeviceMapping;
 for my $d (@devices) {
    print $d->deviceName,"\n";
    print $d->snapshotId,"\n";
    print $d->volumeSize,"\n";
 }
 # run two instances
 my @instances = $image->run_instances(-key_name      =>'My_key',
                                       -security_group=>'default',
                                       -min_count     =>2,
                                       -instance_type => 't1.micro')
           or die $ec2->error_str;
 # wait for both instances to reach "running" or other terminal state
 $ec2->wait_for_instances(@instances);
 # print out both instance's current state and DNS name
 for my $i (@instances) {
    my $status = $i->current_status;
    my $dns    = $i->dnsName;
    print "$i: [$status] $dns\n";
 }
 # tag both instances with Role "server"
 foreach (@instances) {$_->add_tag(Role=>'server');
 # stop both instances
 foreach (@instances) {$_->stop}
 
 # find instances tagged with Role=Server that are
 # stopped, change the user data and restart.
 @instances = $ec2->describe_instances({'tag:Role'       => 'Server',
                                        'instance-state-name' => 'stopped'});
 for my $i (@instances) {
    $i->userData('Secure-mode: off');
    $i->start or warn "Couldn't start $i: ",$i->error_str;
 }
 # create an image from both instance, tag them, and make
 # them public
 for my $i (@instances) {
     my $img = $i->create_image("Autoimage from $i","Test image");
     $img->add_tags(Name  => "Autoimage from $i",
                    Role  => 'Server',
                    Status=> 'Production');
     $img->make_public(1);
 }
 ## KEY MANAGEMENT
 # retrieve the name and fingerprint of the first instance's 
 # key pair
 my $kp = $instances[0]->keyPair;
 print $instances[0], ": keypair $kp=",$kp->fingerprint,"\n";
 # create a new key pair
 $kp = $ec2->create_key_pair('My Key');
 
 # get the private key from this key pair and write it to a disk file
 # in ssh-compatible format
 my $private_key = $kp->private_key;
 open (my $f,'>MyKeypair.rsa') or die $!;
 print $f $private_key;
 close $f;
 # Import a preexisting SSH key
 my $public_key = 'ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQC8o...';
 $key = $ec2->import_key_pair('NewKey',$public_key);
 ## SECURITY GROUPS AND FIREWALL RULES
 # Create a new security group
 my $group = $ec2->create_security_group(-name        => 'NewGroup',
                                         -description => 'example');
 # Add a firewall rule 
 $group->authorize_incoming(-protocol  => 'tcp',
                            -port      => 80,
                            -source_ip => ['192.168.2.0/24','192.168.2.1/24'});
 # Write rules back to Amazon
 $group->update;
 # Print current firewall rules
 print join ("\n",$group->ipPermissions),"\n";
 ## VOLUME && SNAPSHOT MANAGEMENT
 # find existing volumes that are available
 my @volumes = $ec2->describe_volumes({status=>'available'});
 # back 'em all up to snapshots
 foreach (@volumes) {$_->snapshot('Backup on '.localtime)}
 # find a stopped instance in first volume's availability zone and 
 # attach the volume to the instance using /dev/sdg
 my $vol  = $volumes[0];
 my $zone = $vol->availabilityZone;
 @instances = $ec2->describe_instances({'availability-zone'=> $zone,
                                        'run-state-name'   => $stopped);
 $instances[0]->attach_volume($vol=>'/dev/sdg') if @instances;
 # create a new 20 gig volume
 $vol = $ec2->create_volume(-availability_zone=> 'us-east-1a',
                            -size             =>  20);
 $ec2->wait_for_volumes($vol);
 print "Volume $vol is ready!\n" if $vol->current_status eq 'available';
 # create a new elastic address and associate it with an instance
 my $address = $ec2->allocate_address();
 $instances[0]->associate_address($address);

DESCRIPTION¶

This is an interface to the 2014-05-01 version of the Amazon AWS API (http://aws.amazon.com/ec2). It was written provide access to the new tag and metadata interface that is not currently supported by Net::Amazon::EC2, as well as to provide developers with an extension mechanism for the API. This library will also support the Open Stack open source cloud (http://www.openstack.org/).

The main interface is the VM::EC2 object, which provides methods for interrogating the Amazon EC2, launching instances, and managing instance lifecycle. These methods return the following major object classes which act as specialized interfaces to AWS:

 VM::EC2::BlockDevice               -- A block device
 VM::EC2::BlockDevice::Attachment   -- Attachment of a block device to an EC2 instance
 VM::EC2::BlockDevice::EBS          -- An elastic block device
 VM::EC2::BlockDevice::Mapping      -- Mapping of a virtual storage device to a block device
 VM::EC2::BlockDevice::Mapping::EBS -- Mapping of a virtual storage device to an EBS block device
 VM::EC2::Group                     -- Security groups
 VM::EC2::Image                     -- Amazon Machine Images (AMIs)
 VM::EC2::Instance                  -- Virtual machine instances
 VM::EC2::Instance::Metadata        -- Access to runtime metadata from running instances
 VM::EC2::Region                    -- Availability regions
 VM::EC2::Snapshot                  -- EBS snapshots
 VM::EC2::Tag                       -- Metadata tags

In addition, there is a high level interface for interacting with EC2 servers and volumes, including file transfer and remote shell facilities:

  VM::EC2::Staging::Manager         -- Manage a set of servers and volumes.
  VM::EC2::Staging::Server          -- A staging server, with remote shell and file transfer
                                        facilities.
  VM::EC2::Staging::Volume          -- A staging volume with the ability to copy itself between
                                        availability zones and regions.

and a few specialty classes:

  VM::EC2::Security::Token          -- Temporary security tokens for granting EC2 access to
                                        non-AWS account holders.
  VM::EC2::Security::Credentials    -- Credentials for use by temporary account holders.
  VM::EC2::Security::Policy         -- Policies that restrict what temporary account holders
                                        can do with EC2 resources.
  VM::EC2::Security::FederatedUser  -- Account name information for temporary account holders.

Lastly, there are several utility classes:

 VM::EC2::Generic                   -- Base class for all AWS objects
 VM::EC2::Error                     -- Error messages
 VM::EC2::Dispatch                  -- Maps AWS XML responses onto perl object classes
 VM::EC2::ReservationSet            -- Hidden class used for describe_instances() request;
                                        The reservation Ids are copied into the Instance
                                         object.

There is also a high-level API called "VM::EC2::Staging::Manager" for managing groups of staging servers and volumes which greatly simplifies the task of creating and updating instances that mount multiple volumes. The API also provides a one-line command for migrating EBS-backed AMIs from one zone to another. See VM::EC2::Staging::Manager.

The interface provided by these modules is based on that described at http://docs.amazonwebservices.com/AWSEC2/latest/APIReference/. The following caveats apply:

 1) Not all of the Amazon API is currently implemented. Specifically,
    a handful calls dealing with cluster management and VM importing
    are missing.  See L</MISSING METHODS> for a list of all the
    unimplemented API calls. Volunteers to fill in these gaps are
    most welcome!
 2) For consistency with common Perl coding practices, method calls
    are lowercase and words in long method names are separated by
    underscores. The Amazon API prefers mixed case.  So in the Amazon
    API the call to fetch instance information is "DescribeInstances",
    while in VM::EC2, the method is "describe_instances". To avoid
    annoyance, if you use the mixed case form for a method name, the
    Perl autoloader will automatically translate it to underscores for
    you, and vice-versa; this means you can call either
    $ec2->describe_instances() or $ec2->DescribeInstances().
 3) Named arguments passed to methods are all lowercase, use
    underscores to separate words and start with hyphens.
    In other words, if the AWS API calls for an argument named
    "InstanceId" to be passed to the "DescribeInstances" call, then
    the corresponding Perl function will look like:
         $instance = $ec2->describe_instances(-instance_id=>'i-12345')
    In most cases automatic case translation will be performed for you
    on arguments. So in the previous example, you could use
    -InstanceId as well as -instance_id. The exception
    is when an absurdly long argument name was replaced with an 
    abbreviated one as described below. In this case, you must use
    the documented argument name.
    In a small number of cases, when the parameter name was absurdly
    long, it has been abbreviated. For example, the
    "Placement.AvailabilityZone" parameter has been represented as
    -placement_zone and not -placement_availability_zone. See the
    documentation for these cases.
 4) For each of the describe_foo() methods (where "foo" is a type of
    resource such as "instance"), you can fetch the resource by using
    their IDs either with the long form:
          $ec2->describe_foo(-foo_id=>['a','b','c']),
    or a shortcut form: 
          $ec2->describe_foo('a','b','c');
    Both forms are listed in the headings in the documentation.
 5) When the API calls for a list of arguments named Arg.1, Arg.2,
    then the Perl interface allows you to use an anonymous array for
    the consecutive values. For example to call describe_instances()
    with multiple instance IDs, use:
       @i = $ec2->describe_instances(-instance_id=>['i-12345','i-87654'])
 6) All Filter arguments are represented as a -filter argument whose value is
    an anonymous hash:
       @i = $ec2->describe_instances(-filter=>{architecture=>'i386',
                                               'tag:Name'  =>'WebServer'})
    If there are no other arguments you wish to pass, you can omit the
    -filter argument and just pass a hashref:
       @i = $ec2->describe_instances({architecture=>'i386',
                                      'tag:Name'  =>'WebServer'})
    For any filter, you may represent multiple OR arguments as an arrayref:
      @i = $ec2->describe-instances({'instance-state-name'=>['stopped','terminated']})
    When adding or removing tags, the -tag argument uses the same syntax.
 7) The tagnames of each XML object returned from AWS are converted into methods
    with the same name and typography. So the <privateIpAddress> tag in a
    DescribeInstancesResponse, becomes:
           $instance->privateIpAddress
    You can also use the more Perlish form -- this is equivalent:
          $instance->private_ip_address
    Methods that correspond to complex objects in the XML hierarchy
    return the appropriate Perl object. For example, an instance's
    blockDeviceMapping() method returns an object of type
    VM::EC2::BlockDevice::Mapping.
    All objects have a fields() method that will return the XML
    tagnames listed in the AWS specifications.
      @fields = sort $instance->fields;
      # 'amiLaunchIndex', 'architecture', 'blockDeviceMapping', ...
 8) Whenever an object has a unique ID, string overloading is used so that 
    the object interpolates the ID into the string. For example, when you
    print a VM::EC2::Volume object, or use it in another string context,
    then it will appear as the string "vol-123456". Nevertheless, it will
    continue to be usable for method calls.
         ($v) = $ec2->describe_volumes();
         print $v,"\n";                 # prints as "vol-123456"
         $zone = $v->availabilityZone;  # acts like an object
 9) Many objects have convenience methods that invoke the AWS API on your
    behalf. For example, instance objects have a current_status() method that returns
    the run status of the object, as well as start(), stop() and terminate()
    methods that control the instance's lifecycle.
         if ($instance->current_status eq 'running') {
             $instance->stop;
         }
 10) Calls to AWS that have failed for one reason or another (invalid
    arguments, communications problems, service interruptions) will
    return undef and set the VM::EC2->is_error() method to true. The
    error message and its code can then be recovered by calling
    VM::EC2->error.
      $i = $ec2->describe_instance('i-123456');
      unless ($i) {
          warn 'Got no instance. Message was: ',$ec2->error;
      }
    You may also elect to raise an exception when an error occurs.
    See the new() method for details.

ASYNCHRONOUS CALLS¶

As of version 1.24, VM::EC2 supports asynchronous calls to AWS using AnyEvent::HTTP. This allows you to make multiple calls in parallel for a significant improvement in performance.

In asynchronous mode, VM::EC2 calls that ordinarily wait for AWS to respond and then return objects corresponding to EC2 instances, volumes, images, and so forth, will instead immediately return an AnyEvent condition variable. You can retrieve the result of the call by calling the condition variable's recv() method, or by setting a callback to be executed when the call is complete.

To make an asynchronous call, you can set the global variable $VM::EC2::ASYNC to a true value

Here is an example of a normal synchronous call:

 my @instances = $ec2->describe_instances();

Here is the asynchronous version initiated after setting $VM::EC2::ASYNC (using a local block to limit its effects).

 {
    local $VM::EC2::ASYNC=1;
    my $cv = $ec2->describe_instances();   # returns immediately
    my @instances = $cv->recv;
 }

In case of an error recv() will return undef and the error object can be recovered using the condition variable's error() method (this is an enhancement over AnyEvent's standard condition variable class):

 my @instances = $cv->recv 
    or die "No instances found! error = ",$cv->error();

You may attach a callback CODE reference to the condition variable using its cb() method, in which case the callback will be invoked when the APi call is complete. The callback will be invoked with a single argument consisting of the condition variable. Ordinarily you will call recv() on the variable and then do something with the result:

 {
   local $VM::EC2::ASYNC=1;
   my $cv = $ec2->describe_instances();
   $cv->cb(sub {my $v = shift;
                my @i = $v->recv;
                print "instances = @i\n"; 
                });
  }

For callbacks to be invoked, someone must be run an event loop using one of the event frameworks that AnyEvent supports (e.g. Coro, Tk or Gtk). Alternately, you may simply run:

 AnyEvent->condvar->recv();

If $VM::EC2::ASYNC is false, you can issue a single asynchronous call by appending "_async" to the name of the method call. Similarly, if $VM::EC2::ASYNC is true, you can make a single normal synchrous call by appending "_sync" to the method name.

For example, this is equivalent to the above:

 my $cv = $ec2->describe_instances_async();  # returns immediately
 my @instances = $cv->recv;

You may stack multiple asynchronous calls on top of one another. When you call recv() on any of the returned condition variables, they will all run in parallel. Hence the three calls will take no longer than the longest individual one:

 my $cv1 = $ec2->describe_instances_async({'instance-state-name'=>'running'});
 my $cv2 = $ec2->describe_instances_async({'instance-state-name'=>'stopped'});
 my @running = $cv1->recv;
 my @stopped = $cv2->recv;

Same thing with callbacks:

 my (@running,@stopped);
 my $cv1 = $ec2->describe_instances_async({'instance-state-name'=>'running'});
 $cv1->cb(sub {@running = shift->recv});
 my $cv2 = $ec2->describe_instances_async({'instance-state-name'=>'stopped'});
 $cv1->cb(sub {@stopped = shift->recv});
 AnyEvent->condvar->recv;

And here it is using a group conditional variable to block until all pending describe_instances() requests have completed:

 my %instances;
 my $group = AnyEvent->condvar;
 $group->begin;
 for my $state (qw(pending running stopping stopped)) {
    $group->begin;
    my $cv = $ec2->describe_instances_async({'instance-state-name'=>$state});
    $cv->cb(sub {my @i = shift->recv;
                 $instances{$state}=\@i;
                 $group->end});
 }
 $group->recv;
 # when we get here %instances will be populated by all instances,
 # sorted by their state.

If this looks mysterious, please consult AnyEvent for full documentation and examples.

Lastly, be advised that some of the objects returned by calls to VM::EC2, such as the VM::EC2::Instance object, will make their own calls into VM::EC2 for certain methods. Some of these methods will block (be synchronous) of necessity, even if you have set $VM::EC2::ASYNC. For example, the instance object's current_status() method must block in order to update the object and return the current status. Other object methods may behave unpredictably in async mode. Caveat emptor!

API GROUPS¶

The extensive (and growing) Amazon API has many calls that you may never need. To avoid the performance overhead of loading the interfaces to all these calls, you may use Perl's import mechanism to load only those modules you care about. By default, all methods are loaded.

Loading is controlled by the "use" import list, and follows the conventions described in the Exporter module:

 use VM::EC2;                     # load all methods!
 use VM::EC2 'key','elastic_ip';  # load Key Pair and Elastic IP
                                  # methods only
 use VM::EC2 ':standard';         # load all the standard methods
 use VM::EC2 ':standard','!key';  # load standard methods but not Key Pair

Related API calls are grouped together using the scheme described at http://docs.aws.amazon.com/AWSEC2/latest/APIReference/OperationList-query.html. The modules that define the API calls can be found in VM/EC2/REST/; you can read their documentation by running perldoc VM::EC2::REST::"name of module":

 perldoc VM::EC2::REST::elastic_ip

The groups that you can import are as follows:

 :standard => ami, ebs, elastic_ip, instance, keys, general,
              monitoring, tag, security_group, security_token, zone
 :vpc      => customer_gateway, dhcp, elastic_network_interface, 
              private_ip, internet_gateway, network_acl, route_table,
              vpc, vpn, vpn_gateway
 :misc     => devpay, monitoring, reserved_instance,
              spot_instance, vm_export, vm_import, windows
 :scaling  => elastic_load_balancer,autoscaling
 :hpc      => placement_group
 :all      => :standard, :vpn, :misc
 :DEFAULT  => :all

The individual modules are:

 ami               -- Control Amazon Machine Images
 autoscaling       -- Control autoscaling
 customer_gateway  -- VPC/VPN gateways
 devpay            -- DevPay API
 dhcp              -- VPC DHCP options
 ebs               -- Elastic Block Store volumes & snapshots
 elastic_ip        -- Elastic IP addresses
 elastic_load_balancer -- The Elastic Load Balancer service
 elastic_network_interface -- VPC Elastic Network Interfaces
 general           -- Get console output and account attributes
 instance          -- Control EC2 instances
 internet_gateway  -- VPC connections to the internet
 keys              -- Manage SSH keypairs
 monitoring        -- Control instance monitoring
 network_acl       -- Control VPC network access control lists
 placement_group   -- Control the placement of HPC instances
 private_ip        -- VPC private IP addresses
 reserved_instance -- Reserve instances and view reservations
 route_table       -- VPC network routing
 security_group    -- Security groups for VPCs and normal instances
 security_token    -- Temporary credentials for use with IAM roles
 spot_instance     -- Request and manage spot instances
 subnet            -- VPC subnets
 tag               -- Create and interrogate resource tags.
 vm_export         -- Export VMs
 vm_import         -- Import VMs
 vpc               -- Create and manipulate virtual private clouds
 vpn_gateway       -- Create and manipulate VPN gateways within VPCs
 vpn               -- Create and manipulate VPNs within VPCs
 windows           -- Windows operating system-specific API calls.
 zone              -- Interrogate availability zones

EXAMPLE SCRIPT¶

The script sync_to_snapshot.pl, distributed with this module, illustrates a relatively complex set of steps on EC2 that does something useful. Given a list of directories or files on the local filesystem it copies the files into an EBS snapshot with the desired name by executing the following steps:

1. Provisions a new EBS volume on EC2 large enough to hold the data.

2. Spins up a staging instance to manage the network transfer of data from the local machine to the staging volume.

3. Creates a temporary ssh keypair and a security group that allows an rsync-over-ssh.

4. Formats and mounts the volume if necessary.

5. Initiates an rsync-over-ssh for the designated files and directories.

6. Unmounts and snapshots the volume.

7. Cleans up.

If a snapshot of the same name already exists, then it is used to create the staging volume, enabling network-efficient synchronization of the files. A snapshot tag named "Version" is incremented each time you synchronize.

CORE METHODS¶

This section describes the VM::EC2 constructor, accessor methods, and methods relevant to error handling.

 -access_key   Access ID for an authorized user
 -secret_key   Secret key corresponding to the Access ID
 -security_token Temporary security token obtained through a call to the
               AWS Security Token Service
 -endpoint     The URL for making API requests
 -region       The region to receive the API requests
 -raise_error  If true, throw an exception.
 -print_error  If true, print errors to STDERR.

  eval {
     $ec2->some_dangerous_operation();
     $ec2->another_dangerous_operation();
  };
  print STDERR "something bad happened: $@" if $@;

 $current_key = $ec2->access_key;
 $ec2->access_key('XYZZY');

 $old_key = $ec2->access_key($new_key);

  @images = $ec2->describe_images(-owner=>'29731912785');
  unless (@images) {
      die "Error: ",$ec2->error if $ec2->is_error;
      print "No appropriate images found\n";
  }

 $singapore = $ec2->clone;
 $singapore->region('ap-souteast-1');

INSTANCES¶

Load the 'instances' module to bring in methods for interrogating, launching and manipulating EC2 instances. This module is part of the ':standard' API group. The methods are described in detail in VM::EC2::REST::instance. Briefly:

 @i = $ec2->describe_instances(-instance_id=>\@ids,-filter=>\%filters)
 @i = $ec2->run_instances(-image_id=>$id,%other_args)
 @s = $ec2->start_instances(-instance_id=>\@instance_ids)
 @s = $ec2->stop_instances(-instance_id=>\@instance_ids,-force=>1)
 @s = $ec2->reboot_instances(-instance_id=>\@instance_ids)
 $b = $ec2->confirm_product_instance($instance_id,$product_code)
 $m = $ec2->instance_metadata
 @d = $ec2->describe_instance_attribute($instance_id,$attribute)
 $b = $ec2->modify_instance_attribute($instance_id,-$attribute_name=>$value)
 $b = $ec2->reset_instance_attribute($instance_id,$attribute)
 @s = $ec2->describe_instance_status(-instance_id=>\@ids,-filter=>\%filters,%other_args);

VOLUMES¶

Load the 'ebs' module to bring in methods specific for elastic block storage volumes and snapshots. This module is part of the ':standard' API group. The methods are described in detail in VM::EC2::REST::ebs. Briefly:

 @v = $ec2->describe_volumes(-volume_id=>\@ids,-filter=>\%filters)
 $v = $ec2->create_volume(%args)
 $b = $ec2->delete_volume($volume_id)
 $a = $ec2->attach_volume($volume_id,$instance_id,$device)
 $a = $ec2->detach_volume($volume_id)
 $ec2->wait_for_attachments(@attachment)
 @v = $ec2->describe_volume_status(-volume_id=>\@ids,-filter=>\%filters)
 $ec2->wait_for_volumes(@volumes)
 @d = $ec2->describe_volume_attribute($volume_id,$attribute)
 $b = $ec2->enable_volume_io(-volume_id=>$volume_id)
 @s = $ec2->describe_snapshots(-snapshot_id=>\@ids,%other_args)
 @d = $ec2->describe_snapshot_attribute($snapshot_id,$attribute)
 $b = $ec2->modify_snapshot_attribute($snapshot_id,-$argument=>$value)
 $b = $ec2->reset_snapshot_attribute($snapshot_id,$attribute)
 $s = $ec2->create_snapshot(-volume_id=>$vol,-description=>$desc)
 $b = $ec2->delete_snapshot($snapshot_id) 
 $s = $ec2->copy_snapshot(-source_region=>$region,-source_snapshot_id=>$id,-description=>$desc)
 $ec2->wait_for_snapshots(@snapshots)

AMAZON MACHINE IMAGES¶

Load the 'ami' module to bring in methods for creating and manipulating Amazon Machine Images. This module is part of the ':standard" group. Full details are in VM::EC2::REST::ami. Briefly:

 @i = $ec2->describe_images(@image_ids)
 $i = $ec2->create_image(-instance_id=>$id,-name=>$name,%other_args)
 $i = $ec2->register_image(-name=>$name,%other_args)
 $r = $ec2->deregister_image($image_id)
 @d = $ec2->describe_image_attribute($image_id,$attribute)
 $b = $ec2->modify_image_attribute($image_id,-$attribute_name=>$value)
 $b = $ec2->reset_image_attribute($image_id,$attribute_name)

KEYS¶

Load the 'keys' module to bring in methods for creating and manipulating SSH keypairs. This module is loaded with the ':standard' group and documented in VM::EC2::REST::keys.

 @k = $ec2->describe_key_pairs(@names);
 $k = $ec2->create_key_pair($name)
 $k = $ec2->import_key_pair($name,$public_key) 
 $b = $ec2->delete_key_pair($name)

TAGS¶

The methods in this module (loaded with ':standard') allow you to create, delete and fetch resource tags. You may find that you rarely need to use these methods directly because every object produced by VM::EC2 supports a simple tag interface:

  $object = $ec2->describe_volumes(-volume_id=>'vol-12345'); # e.g.
  $tags = $object->tags();
  $name = $tags->{Name};
  $object->add_tags(Role => 'Web Server', Status=>'development);
  $object->delete_tags(Name=>undef);

See VM::EC2::Generic for a full description of the uniform object tagging interface, and VM::EC2::REST::tag for methods that allow you to manipulate the tags on multiple objects simultaneously. The methods defined by this module are:

 @t = $ec2->describe_tags(-filter=>\%filters);
 $b = $ec2->create_tags(-resource_id=>\@ids,-tag=>{key1=>value1...})
 $b = $ec2->delete_tags(-resource_id=>$id1,-tag=>{key1=>value1...})

VIRTUAL PRIVATE CLOUDS¶

EC2 virtual private clouds (VPCs) provide facilities for creating tiered applications combining public and private subnetworks, and for extending your home/corporate network into the cloud. VPC-related methods are defined in the customer_gateway, dhcp, elastic_network_interface, private_ip, internet_gateway, network_acl, route_table, vpc, vpn, and vpn_gateway modules, and are loaded by importing ':vpc'. See VM::EC2::REST::vpc for an introduction.

The VM::EC2::VPC and VM::EC2::VPC::Subnet modules define convenience methods that simplify working with VPC objects. This allows for steps that typically follow each other, such as creating a route table and associating it with a subnet, happen automatically. For example, this series of calls creates a VPC with a single subnet, creates an Internet gateway attached to the VPC, associates a new route table with the subnet and then creates a default route from the subnet to the Internet gateway:

 $vpc       = $ec2->create_vpc('10.0.0.0/16')     or die $ec2->error_str;
 $subnet1   = $vpc->create_subnet('10.0.0.0/24')  or die $vpc->error_str;
 $gateway   = $vpc->create_internet_gateway       or die $vpc->error_str;
 $routeTbl  = $subnet->create_route_table         or die $vpc->error_str;
 $routeTbl->create_route('0.0.0.0/0' => $gateway) or die $vpc->error_str;

ELASTIC LOAD BALANCERS (ELB) AND AUTOSCALING¶

The methods in the 'elastic_load_balancer' and 'autoscaling' modules allow you to retrieve information about Elastic Load Balancers, create new ELBs, and change the properties of the ELBs, as well as define autoscaling groups and their launch configurations. These modules are both imported by the ':scaling' import group. See VM::EC2::REST::elastic_load_balancer and VM::EC2::REST::autoscaling for descriptions of the facilities enabled by this module.

AWS SECURITY POLICY¶

The VM::EC2::Security::Policy module provides a simple Identity and Access Management (IAM) policy statement generator geared for use with AWS security tokens (see next section). Its facilities are defined in VM::EC2::Security::Token.

AWS SECURITY TOKENS¶

AWS security tokens provide a way to grant temporary access to resources in your EC2 space without giving them permanent accounts. They also provide the foundation for mobile services and multifactor authentication devices (MFA). These methods are defined in 'security_token', which is part of the ':standard' group. See VM::EC2::REST::security_token for details. Here is a quick example:

Here is an example:

 # on your side of the connection
 $ec2 = VM::EC2->new(...);  # as usual
 my $policy = VM::EC2::Security::Policy->new;
 $policy->allow('DescribeImages','RunInstances');
 my $token = $ec2->get_federation_token(-name     => 'TemporaryUser',
                                        -duration => 60*60*3, # 3 hrs, as seconds
                                        -policy   => $policy);
 my $serialized = $token->credentials->serialize;
 send_data_to_user_somehow($serialized);
 # on the temporary user's side of the connection
 my $serialized = get_data_somehow();
 my $token = VM::EC2::Security::Credentials->new_from_serialized($serialized);
 my $ec2   = VM::EC2->new(-security_token => $token);
 print $ec2->describe_images(-owner=>'self');

SPOT AND RESERVED INSTANCES¶

The 'spot_instance' and 'reserved_instance' modules allow you to create and manipulate spot and reserved instances. They are both part of the ':misc' import group. See VM::EC2::REST::spot_instance and VM::EC2::REST::reserved_instance. For example:

 @offerings = $ec2->describe_reserved_instances_offerings(
          {'availability-zone'   => 'us-east-1a',
           'instance-type'       => 'c1.medium',
           'product-description' =>'Linux/UNIX',
           'duration'            => 31536000,  # this is 1 year
           });
 $offerings[0]->purchase(5) and print "Five reserved instances purchased\n";

WAITING FOR STATE CHANGES¶

VM::EC2 provides a series of methods that allow your script to wait in an efficient manner for desired state changes in instances, volumes and other objects. They are described in detail the individual modules to which they apply, but in each case the method will block until each member of a list of objects transitions to a terminal state (e.g. "completed" in the case of a snapshot). Briefly:

 $ec2->wait_for_instances(@instances)
 $ec2->wait_for_snapshots(@snapshots) 
 $ec2->wait_for_volumes(@volumes) 
 $ec2->wait_for_attachments(@attachment)

There is also a generic version of this defined in the VM::EC2 core:

INTERNAL METHODS¶

These methods are used internally and are listed here without documentation (yet).

   [
           {
                   ParameterName=>'max_user_connections',
                   ParameterValue=>24,
                   ApplyMethod=>'pending-reboot'
           },
           {
                   ParameterName=>'max_allowed_packet',
                   ParameterValue=>1024,
                   ApplyMethod=>'immediate'
           },
   ];

    $VM::EC2::ASYNC = 1;
    my $cv  = $ec2->call('DescribeInstances');
    my @obj = $cv->recv;

    $VM::EC2::ASYNC = 1;
    my $cv  = $ec2->call('DescribeInstances');
    $cv->cb(sub { my @objs = shift->recv;
                  do_something(@objs);
                });

  -credentials => $fed_token->credentials - Credentials from an $ec2->get_federation_token call
  -token => $token                        - a SigninToken from $ec2->get_signin_token call
  -issuer => $issuer_url
  -destination => $console_url            - URL of the AWS console. Defaults to https://console.aws.amazon.com/console/home
  -auto_scaling_group_names     List of auto scaling groups to describe
  -names                        Alias of -auto_scaling_group_names

  my $fed_token = $ec2->get_federation_token(...);
  my $token = $ec2->get_signin_token(-credentials => $fed_token->credentials);
  my $url = $ec2->login_url(-token => $token->{SigninToken}, -issuer => $issuer_url, -destination => $console_url);

  my $fed_token = $ec2->get_federation_token(...);
  my $url = $ec2->login_url(-credentials => $fed_token->credentials, -issuer => $issuer_url, -destination => $console_url);

OTHER INFORMATION¶

This section contains technical information that may be of interest to developers.

  $ec2 = VM::EC2->new(-endpoint=>'https://ec2.amazonaws.com');

 VM::EC2::Dispatch->register($call_name => $dispatch).

 1) A CODE references, such as an anonymous subroutine.
    In this case the code reference will be invoked to handle the 
    parsed XML returned from the request. The code will receive 
    two arguments consisting of the parsed
    content of the response, and the VM::EC2 object used to generate the
    request.
 2) A VM::EC2::Dispatch method name, optionally followed by its arguments
    delimited by commas. Example:
           "fetch_items,securityGroupInfo,VM::EC2::SecurityGroup"
    This tells Dispatch to invoke its fetch_items() method with
    the following arguments:
     $dispatch->fetch_items($parsed_xml,$ec2,'securityGroupInfo','VM::EC2::SecurityGroup')
    The fetch_items() method is used for responses in which a
    list of objects is embedded within a series of <item> tags.
    See L<VM::EC2::Dispatch> for more information.
    Other commonly-used methods are "fetch_one", and "boolean".
 3) A class name, such as 'MyVolume'
    In this case, class MyVolume is loaded and then its new() method
    is called with the four arguments ($parsed_xml,$ec2,$xmlns,$requestid),
    where $parsed_xml is the parsed XML response, $ec2 is the VM::EC2
    object that generated the request, $xmlns is the XML namespace
    of the XML response, and $requestid is the AWS-generated ID for the
    request. Only the first two arguments are really useful.
    I suggest you inherit from VM::EC2::Generic and use the inherited new()
    method to store the parsed XML object and other arguments.

 XML::Simple->new(ForceArray    => ['item'],
                  KeyAttr       => ['key'],
                  SuppressEmpty => undef);

 my ($i) = $ec2->describe_instances;
 print $i->as_string;

 package 'VM::EC2New';
 use base 'VM::EC2';
  sub new {
      my $self=shift;
      VM::EC2::Dispatch->register('call_name_1'=>\&subroutine1).
      VM::EC2::Dispatch->register('call_name_2'=>\&subroutine2).
      $self->SUPER::new(@_);
 }

DEVELOPING¶

The git source for this library can be found at https://github.com/lstein/LibVM-EC2-Perl, To contribute to development, please obtain a github account and then either:

 1) Fork a copy of the repository, make your changes against this repository, 
    and send a pull request to me to incorporate your changes.
 2) Contact me by email and ask for push privileges on the repository.

See http://help.github.com/ for help getting started.

SEE ALSO¶

Net::Amazon::EC2 VM::EC2::Dispatch VM::EC2::Generic VM::EC2::BlockDevice VM::EC2::BlockDevice::Attachment VM::EC2::BlockDevice::EBS VM::EC2::BlockDevice::Mapping VM::EC2::BlockDevice::Mapping::EBS VM::EC2::Error VM::EC2::Generic VM::EC2::Group VM::EC2::Image VM::EC2::Instance VM::EC2::Instance::ConsoleOutput VM::EC2::Instance::Metadata VM::EC2::Instance::MonitoringState VM::EC2::Instance::PasswordData VM::EC2::Instance::Set VM::EC2::Instance::State VM::EC2::Instance::State::Change VM::EC2::Instance::State::Reason VM::EC2::KeyPair VM::EC2::Region VM::EC2::ReservationSet VM::EC2::ReservedInstance VM::EC2::ReservedInstance::Offering VM::EC2::SecurityGroup VM::EC2::Snapshot VM::EC2::Staging::Manager VM::EC2::Tag VM::EC2::Volume

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.