Public Cloud – AWS

The Public Cloud (AWS) serious of article will help you know more about AWS and its commonly used services and how to use them.

The term “Cloud Computing” refers to the on-demand delivery of IT resources via the Internet with pay-as-you-go pricing. Major advantage of cloud computing are :

Low Ongoing Cost	Reduce your overall IT costs
No Upfront Investment	Replace upfront infrastructure investment with low monthly costs
Apps not Ops	Focus on projects that differentiate your business, not the infrastructure
Flexible Capacity	Eliminate guessing on your infrastructure capacity needs
Speed & Agility	Develop and deploy applications faster
Global Reach	Take your apps global in minutes

What is AWS?
Amazon Web Services (AWS) offering IT infrastructure services to businesses in the form of collection of remote computing services, also called web services, that make up a cloud computing platform by Amazon.

Note: [*] The first AWS service launched for public usage was Simple Queue Service in November 2004.

Basic Concepts related to AWS Infrastructure

AWS Management Console
AWS Management Console is a graphical user interface that Amazon kept up to date with their own API. It can be access online at https://console.aws.amazon.com/ and it is the fastest way to get started with Amazon AWS to access various resources/services. It performs many of the required functions very well, but several functions are easier to control from other applications.
The AWS Management Console supports the Firefox, Chrome, Internet Explorer, Safari browsers and for mobile app.

Amazon Elastic Compute Cloud (EC2)
Amazon Elastic Compute Cloud (EC2) is a core part of Amazon cloud computing platform, Amazon Web Services (AWS). EC2 allows users to rent virtual computers on which to run their own computer applications. EC2 allows scalable deployment of applications by providing a Web service through which a user can boot an Amazon Machine Image (AMI) to create a virtual machine, which Amazon calls an “instance”, containing any software desired. A user can create, launch, and terminate server instances as needed, paying by the hour for active servers. EC2 provides users with control over the geographical location of instances that allows for latency optimization and high levels of redundancy.

You can use Amazon EC2 to launch as many or as few virtual servers as you need, configure security and networking, and manage storage. Amazon EC2 enables you to scale up or down to handle changes in requirements or spikes in popularity, reducing your need to forecast traffic.

Note: [*] Amazon EC2 resources are either global, tied to a region, or tied to an Availability Zone.
            [*] AWS announced a limited public beta test of EC2 on August 25, 2006.

Region
AWS is geographically diversified into regions to minimize the impact of outages and ensure robustness of the system. It is completely isolated from the other Amazon EC2 regions. It give flexibility to user to launch instances that are geographically closer to targeted user/customers or to meet legal requirements. All communications between regions is across the public Internet.

S.No.	Name	Code
1	(N. Virginia) US East	us-east-1
2	(N. California) US West	us-west-1
3	(Oregon) US West	us-west-2
4	(Sao Paulo) South America	sa-east-1
5	(Frankfurt) EU	eu-central-1
6	(Ireland) EU	eu-west-1
7	(Tokyo) Asia Pacific	ap-northeast-1
8	(Singapore) Asia Pacific	ap-southeast-1
9	(Sydney) Asia Pacific	ap-southeast-2
10	(Beijing) China	(Upcoming)

Note: [*] Resources (AWS services) are bound to the region we specified and not all resources are available in each and every regions and Availability Zones.
            [*] AWS do not replicate resources across regions automatically.
            [*] Data transfer between regions is charged at the Internet data transfer rate for both sending and the receiving instance.

Availability Zone
Each region comprises multiple smaller geographic areas called availability zones. This is a sub-set of a Region to provide fault tolerance to aws resources. Amazon EC2 provides you the ability to place resources, such as instances, and data in multiple locations. Each Availability Zone is isolated, but the Availability Zones in a region are connected through low-latency links.

Amazon operates state-of-the-art, highly-available data centers. Although rare, failures can occur that affect the availability of instances that are in the same location. If you host all your instances in a single location that is affected by such a failure, none of your instances would be available.

If you distribute your instances across multiple Availability Zones and one instance fails, you can design your application so that an instance in another Availability Zone can handle requests.

Note: [*] AWS restrict AZ per account so your account might have a different number of available Availability Zones in a region than another account.
            [*] You can select an Availability Zone or let AWS choose one for you.

Amazon Machine Image (AMI)
An Amazon Machine Image (AMI) is a pre-built image of virtual appliance that is used to instantiate (create) a virtual machine within the Amazon EC2. It serves as the basic unit of deployment for services delivered using EC2. It provides the information required to launch an instance like templates that are configured with an operating system and other software, which determine the user’s operating environment. AMI types are categorized according to region, operating system, system architecture (32- or 64-bit), launch permissions and whether they are backed by Amazon EBS or Instance store.

Amazon Elastic Block Storage (EBS)
Amazon Elastic Block Storage (EBS) provides persistent raw block devices that can be attached to Amazon EC2 instances. Each Amazon EBS volume is automatically replicated within its Availability Zone to protect you from component failure, offering high availability and durability. In addition EBS supports a number of advanced storage features, including snapshotting and cloning. EBS provides the following volume types: General Purpose (SSD), Provisioned IOPS (SSD), and Magnetic. They differ in performance characteristics and price, allowing you to tailor your storage performance and cost to the needs of your applications.

Amazon EBS is ideal if you’re doing any substantial work with EC2, you want to keep data persistently on a file system, and you want to keep that data around even after you shut down your EC2 instance.

Note: [*] EBS volumes can be up to 1TB in size.
            [*] It can only be attached to one instance at a time.
            [*] The EBS product was introduced to the general public by Amazon in August 2008.

Elastic IP Addresses (EIP)
Elastic IP addresses are publically accessible addresses, they allow a layer of visualization as you can associate the Elastic IP with any server in your Availability zone. You can associate it to and from instances as you require, with an EIP you can mask the failure of an instance or software by rapidly remapping the address to another instance in your account.

Note: [*] EIP is allocated to your account until you choose to release it.

Key Pairs
Key pairs consist of a public and private key (often referred to as a keypair in EC2). The ssh key-pair are used to make sure that only you can access your EC2 instances. When you run an instance, you specify the name of the keypair and the corresponding public key is provided to that instance. When you ssh to the above username on the instance, you specify the private key so the instance can authenticate you and let you in. You generally never see or deal with the public key as EC2 keeps this copy and provides it to the instances. You download the private key and save it when it is generated.

Note: [*] Key pairs are used only for Amazon EC2 and Amazon CloudFront.
            [*] Linux instances have password login disabled, and we use a key pair to log in using SSH.
            [*] You can have multiple ssh keypairs associated with a single AWS account.
            [*] It is also used to generate initial Windows Instance Administrative Password.