By default, all Amazon EC2 instances are assigned two IP addresses at launch: a private (RFC 1918) address and a public address that is mapped to the private IP address through Network Address Translation (NAT).
If you use dynamic DNS to map an existing DNS name to a new instance's public IP address, it might take up to 24 hours for the IP address to propagate through the Internet. As a result, new instances might not receive traffic while terminated instances continue to receive requests.
To solve this problem, Amazon EC2 provides elastic IP addresses. Elastic IP addresses are static IP addresses designed for dynamic cloud computing. Elastic IP addresses are associated with your account, not specific instances. Any elastic IP addresses that you associate with your account remain associated with your account until you explicitly release them. Unlike traditional static IP addresses, however, elastic IP addresses allow you to mask instance or Availability Zone failures by rapidly remapping your public IP addresses to any instance in your account.
Example 733. Allocating a new Elastic IP
allocate will assign your account a new Elastic IP Address.
allocate returns the newly allocated ip.
$ec2_eip = new Zend_Service_Amazon_Ec2_Elasticip('aws_key','aws_secret_key');
$ip = $ec2_eip->allocate();
// print out your newly allocated elastic ip address;
print $ip;
Example 734. Describing Allocated Elastic IP Addresses
describe has an optional parameter to describe all
of your allocated Elastic IP addresses or just some of your
allocated addresses.
describe returns an array that contains information on each Elastic IP
Address which contains the publicIp and the instanceId if it is assocated.
$ec2_eip = new Zend_Service_Amazon_Ec2_Elasticip('aws_key','aws_secret_key');
// describe all
$ips = $ec2_eip->describe();
// describe a subset
$ips = $ec2_eip->describe(array('ip1', 'ip2', 'ip3'));
// describe a single ip address
$ip = $ec2_eip->describe('ip1');
Example 735. Releasing Elastic IP
release will release an Elastic IP to Amazon.
Returns a boolean TRUE or FALSE.
$ec2_eip = new Zend_Service_Amazon_Ec2_Elasticip('aws_key','aws_secret_key');
$ec2_eip->release('ipaddress');
Example 736. Associates an Elastic IP to an Instance
associate will assign an Elastic IP to an
already running instance.
Returns a boolean TRUE or FALSE.
$ec2_eip = new Zend_Service_Amazon_Ec2_Elasticip('aws_key','aws_secret_key');
$ec2_eip->associate('instance_id', 'ipaddress');
Example 737. Disassociate an Elastic IP from an instance
disassociate will disassociate an Elastic IP from an instance.
If you terminate an Instance it will automaticly disassociate the Elastic
IP address for you.
Returns a boolean TRUE or FALSE.
$ec2_eip = new Zend_Service_Amazon_Ec2_Elasticip('aws_key','aws_secret_key');
$ec2_eip->disassociate('ipaddress');