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Q: What is EC2?

A: EC2 is an Infrastructure as a Service Cloud Computing Platform provided by Amazon Web Services, that allows users to instantiate various types of virtual machines.

Q: What is an instance?

A: An EC2 instance is a Virtual Machine running on Amazon's EC2 Cloud.

Q: What is an AMI?

A: An AMI (Amazon Machine Image) is a preconfigured bootable machine image, that allows one to instantiate an EC2 instance. (EC2 Virtual Machine)

Q: What is an AKI?

A: An AKI (Amazon Kernel Image) is a preconfigured bootable kernel miniimage, that are prebuild and provided by Amazon to boot instances. Typically one will use an AKI that contains pv-grub so that one can instantiate an instance from an AMI that contains it's own Xen DomU kernel that is managed by the user.

Q: What is EBS?

A: EBS stands for Elastic Block Storage, and is a service that provides dynamically allocatable, persistent, block storage volumes that can be attached to EC2 instances. Most system operations that can be performed with an HDD can be performed with an EBS volume. e.g. - formatted with a filesystem and mounted. EBS also provides additional SAN-like features such as taking snapshots of volumes, and detaching and reattaching volumes dynamically. One notable feature that SAN LUNs support that EBS volumes do not is muti-initiator. (IE: Only a single EC2instance can be associated with a given EBS volume at a given time, so shared storage clustering is currently not supported.)

Q: What is the difference between an instance-store AMI/instance and an EBS AMI/instance?

A: An instance-store instance boots off of an AMI that instantiates a non-persistent root volume that loses all data on poweroff, or hardware failure. EBS instances boot off an AMI that consists of an EBS volume that persists after powering off (stopping) an instance or in the event of a hardware failure a given instance is running on. EBS root volumes can be snap-shotted and cloned, like other EBS volumes.

Q: What is the difference between terminating an instance and stopping an instance?

A: Please note this difference is only applicable to EBS-root instances. When one stops an instance it basically virtually powers off the instance but it remains in the inventory to be powered on (started) again. Terminating an instance removes its records from the system inventory and usually also deletes its root volume.

Q: How does IP addressing work in EC2?

A: In "classic EC2" each instance is given a randomly assigned private IP address that maps via NAT to an also randomly assigned public IP address. VPC instances allow more control of the private (and public) IP address mappings and assignment, and as such let one assign custom private IP ranges and addresses, in addition to having the option to not assign public IP address mappings.

Q: What is an Elastic IP Address (EIP)?

A: An Elastic IP address is a Public IP addressed that is assigned to an individual AWS account. These IPs are assigned by region. This address can be assigned to any EC2 instance within a region and will replace the regularly assigned random public IP address.

Q: What is an EC2 Region?

A: An EC2 Region refers to a geographic region that is a completely autonomous set of compute resources, with their own management infrastructure. Regions do not share any resources, so they are considered completely separate for disaster recovery purposes.

Q: What EC2 Regions are there?

A: us-east-1 (Virginia), us-west-1 (N. California), us-west-2 (Oregon), eu-west-1 (Ireland), ap-southeast-1 (Singapore), ap-northeast-1 (Tokyo), ap-southeast-2 (Sydney), sa-east-1 (Sao Paulo)

Q: What is an EC2 Availability Zone?

A: An availability zone is a separate "failure zone" within a given region that can have resources instantiated in. Each region has it's own power grid, and physical set of hardware and resources. Availability zones within a given region have a shared management interface/infrastructure.

Q: What is an EC2 Security Group?

A: A Security Group (SG) is a management construct within EC2 that acts similarily to a network based firewall. An instance must be assigned one or more security groups at first instantiation. Security group membership may not change after initial instantiation. Security groups allow one to set incoming network rules allowing certain TCP/UDP/ICMP protocols ingress via rules based on incoming security group ID, network address or IP address. Security groups do not restrict outbound traffic, nor do they restrict traffic between instances within the same security group. (Assuming they are communicating via their private IP addresses.)

Q: What is instance metadata?

A: Instance metadata is descriptive information about a particular instance, that is available via an http call to a particular instance and that instance alone. e.g. - Public IP address, availability zone, etc. userdata is one of these pieces of data available.

Q: What is userdata?

A: When one instantiates an EC2 instances one may optionally pass 16 KB of data to the API that can be used by the instance. (Typically use cases are running scripts, and/or configuring the instance to meet a particular use case.)

Q: What is cloud-init?

A: Cloud-init is a framework written in Python for handling EC2 userdata to configure a newly instantiated EC2 instance. See upstream project for more details:

Q: How do I log into a Debian EC2 instance for the first time?

A: When you instantiate an instance from an official Debian AMI, one needs to assign a previously uploaded/created ssh public key, which will be added to the "admin" user's authorized_keys. One can then ssh in as "admin" and use sudo to add additional users.

Q: What are the different methods supported to manage EC2?

A: Either via the AWS Web Console, via the API, or via CLI tools.

Q: How do I get to the AWS Web Console?


Q: Where is the EC2 API documented?


Q: Where can I find the CLI tools to manage EC2?

A: The original Amazon EC2 API Tools are not DFSG-compliant, but are officially supported by Amazon. There is an alternate set of DFSG-compliant tools, that are designed to be fully compatible called ?eucatools, which can be installed via apt-get install euca2ools. More recently, Amazon released the AWS Command Line Interface under a DFSG-compliant license. As of August 2014, this is available via apt-get install awscli in Debian Testing and Debian Unstable, but is not yet in a stable Debian version.

Q: Where can I find the list of Official Debian AMIs?

A: The following page has a list of Official and unofficial Debian AMIs: Cloud/AmazonEC2Image. See also 694035 for work in progress on a machine-readable list.

Q: How can I build my own AMI?

A: Anders Ingemann has created a build script for bootstrapping instances, and was used to create the official AMIs. The script can be automated as it needs no user interaction. Custom scripts can be attached to the process as well. You can download or clone the script from github. Any bugs or suggestions should be reported via the github issue tracker. The script is packaged and will be available for install starting with Debian Wheezy.

Q: How can I accept AWS Marketplace terms ?

Attempts to run an official Debian AMI from a naive account return error messages such as the following.

OptInRequired: In order to use this AWS Marketplace product you need to accept terms and subscribe. To do so please visit

What is the procedure to accept AWS Marketplace terms ? Can it be done from the command line ?

A: The terms and conditions for Marketplace published AMIs can only be accepted via the web site, and not via the command line or API directly. The EULA is required to be shown to the customer (in the case of the Debian AMIs in Marketplace, it is the Debian Social Contract which is displayed to the customer).