Glossary

EC2 stands for Amazon's Elastic Compute Cloud. Using EC2 you can launch instances (specific packages of dedicated compute resources) that look and feel just like traditional remote servers. Resources are delivered in a matter of seconds, not days or weeks as with traditional providers and you can now request 10, 100, 1000+ servers based on your web applications needs at any given time. EC2 changes the way that computing resources are delivered to the consumer. You are no longer limited by server capacity or long term service contracts. EC2 delivers a utility computing model where you pay as you go and only pay for what you use. It also provides full control of these resources where you can launch and terminate new servers at will.

For more information about EC2, including instance sizes, pricing, and to sign up for EC2 visit, http://aws.amazon.com/ec2.

AWS is short for Amazon Web Services. In addition to selling books and variety of other consumer products, Amazon also offers a variety of web services that help web developers build next generation web platforms.

RightScale offers a web interface that's designed to make it easier to use the following AWS Services:

• EC2 - Elastic Compute Cloud
• S3 - Simple Storage Service
• SQS - Simple Queue Service

An instance is the AWS version of a server. They come in a variety of sizes small, large, and extra-large and are designed to provide predictable and dedicated computing power on demand. Amazon charges you directly based on instance-per-hour usage.

A compute unit is measurement tool used to compare and contrast different virtual servers (instances). One EC2 Compute Unit provides the equivalent CPU capacity of a 1.0-1.2 GHz 2007 Opteron or 2007 Xeon processor. This is also the equivalent to an early-2006 1.7 GHz Xeon processor.

An AMI is a packaged environment that contains a configured Linux operating system. We recommend using our own custom RightImages. They contain a lightweight server installation with all of the tools necessary to use EC2 and RightScale. All of our scripts are provided to our customers for further customization to meet your needs.

When you launch an image through AWS, you will specify a particular SSH Key to associate with that image. This allows you to gain access to your machines without using passwords. This is the recommended (and more secure) way to access your instances. RightScale uses this key to communicate and monitor your instances. Do not change it.

A security group is Amazon's version of a firewall that includes some additional features. It allows you to specify certain security settings on an instance specific basis. You have the ability to filter traffic based on IP's (a specific address or a subnet), packet types (TCP, UDP or ICMP), and ports (or a range of ports). You can also grant access to an entire security group. This allows your trusted machines to access each other without having to open ports to the public.

For even more security, Amazon provides the option of completely removing public access to an instance. This will ensure that you are safe from any outsiders gaining access to your machine and even prevents 'Denial of Service' attacks.

An Elastic IP (EIP) is an IP address that you can reserve from AWS for your account. Once you've created an Elastic IP, you can assign it to any instance of your choice. Once you reserve an Elastic IP, nobody else can use that IP address. With Elastic IPs, you can now allocate an IP address and assign it to an instance of your choice, which replaces the need for normal dynamic IP addressing in the cloud. Elastic IPs are dynamically remappable IP addresses that make it easier to manage servers and make global changes compared to static IPs on traditional hosting solutions, because each EIP can be reassigned to a different instance when needed. It's a way of ensuring that you don't 'inherit' traffic from other's servers on EC2, because you're using an IP that's specifically reserved for your usage only, as long as you keep that EIP.

Elastic Block Store (EBS) adds to the persistent storage of EC2; random access block storage with volumes. EBS provides persistent, high-performance, and high-availability block-level storage which you can attach to a running EC2 instance (in the same availability zone) in the form of volumes (1GB - 1TB). Each EBS volume can be formatted and mounted as a file system. You also have direct, random access of each stored block of data.

Amazon CloudFront is a web service for content delivery. It integrates with other Amazon Web Services to give developers and businesses an easy way to distribute content to end users with low latency, high data transfer speeds, and no commitments. Amazon CloudFront delivers your content using a global network of edge locations. Requests for your objects are automatically routed to the nearest edge location, so content is delivered with the best possible performance.

Amazon Simple Storage Service (S3) is the distributed storage component of the AWS platform. It can read, write, and delete objects representing data ranging from 1 byte to 5 gigabytes. You can use S3 to store, replicate, and persist an unlimited amount of objects in the cloud. However, you should not think of S3 as a local disk and attempt to run your database from S3.

S3 simply stores "objects" or files, in "buckets" (folders). Since there are no directories in S3, each bucket is given a unique identifier. You can also have multiple buckets under one account. Many customers serve static files such as images or video directly from S3 instead of having them stored on a local disk. This gives them virtually infinite storage capacity for their files without purchasing any hardware.

RightScale provides an S3 Browser and an EC2 Image Locator to help you scan and monitor your buckets.

For more information visit: http://aws.amazon.com/s3.

A bucket is an S3 storage area assigned using a unique key. You can use buckets to make data public or private, and authenticate user access to your data. Currently, you can also requisition buckets in North America and Europe. Data in these buckets are stored in those geographic locations, but can be accessed from anywhere based on the authentication credentials that you specify.

Objects are stored inside buckets. They are the fundamental entities in S3.

A key uniquely identifies the object within a bucket. Together, a key and a bucket are used to identify an object inside S3.

A deployment is a clustered architecture that represents all of the instances (servers) in your application and associates them with each other. It may include web front ends, application servers, worker slave machines, and your database servers. At the deployment level you can specify global parameters that all of the instances inherit, which makes it really easy to add additional components without the need for extra configuration. The RightScale Dashboard makes it easy for you to start and stop entire deployments on demand, clone deployment clusters to create identical staging or QA environments, and define and link variables that apply to scripts distributed across all of your servers. Creating a deployment is as easy as selecting and adding the servers you want, defining your variables, and clicking Launch.

An array is a single server type linked to a deployment that is used for horizontal scaling. For example, if there is an instance that you would like to launch multiple copies of, such as an application server or worker slave task, you should define it as an array. Setting the elasticity parameters of that array allows RightScale to make decisions when to grow or shrink the size of that array. Parameters may include load-based thresholds, scheduled scaling, or number of jobs in a queue. RightScale uses a unique voting system to take the status of all of your related instances into consideration before making the decision to launch or terminate new servers. This safety feature ensures that no one single instance is responsible for executing a decision that may not reflect the total load across your entire deployment.

A ServerTemplate defines the composition and configuration of your instance. When an instance is launched from a ServerTemplate, it uses a base OS image and a series of scripts to install and configure your server as it boots. This allows you to work at a much more granule level than simply from an AMI alone.

A RightScript is any script that you define within RightScale. It may be a shell script, a perl script, a ruby script, a python script, etc. These scripts can be defined as boot scripts for a ServerTemplate, which run at boot time, or as operational scripts, where they can be run from the Scripts tab in the RightScale Dashboard on an operational instance. Decommission scripts are also available for defining a proper shutdown procedure. You can also connect RightScripts to escalation actions and have them run when a particular alert condition is met.

A RightImage is a base operating system. We feel it is always best to start with a predictable and stable base image before building your application using a series of RightScripts. RightImages are publicly available through the AWS website and through our Dashboard.

An escalation is the action that RightScale will take on your behalf when a particular associated alert condition is met. An escalation may be anything from sending an email, rebooting a server, relaunching the instance, running a RightScript, or voting to grow or shrink the size of an array.

An alert is a flag for a particular condition. It may be hardware or process-specific. Our monitoring daemons collect a wide variety of information from your instances. Any of these metrics may be linked to an alert, which in turn may be linked to a particular action using an escalation.