Amazon Elastic Compute Cloud and Amazon Elastic Block Store-2

Configuring an Environment for Your Instance

Deciding where your EC2 instance will live is as important as choosing performance configuration. Here, there are three primary details to get right: geographic region, virtual private cloud (VPC), and tenancy model. AWS Regions As you learned earlier, AWS servers are housed in data centers around the world and organized by geographical region. You’ll generally want to launch an EC2 instance in the region that’s physically closest to the majority of your customers or, if you’re working with data that are subject to legal restrictions, within a jurisdiction that meets your compliance needs. EC2 resources can be managed only when you’re “located within” their region. You set the active region in the console through the drop-down menu at the top of the page and through default configuration values in the AWS CLI or your SDK. You can update your CLI configuration by running aws configure. Bear in mind that the costs and even functionality of services and features might vary between regions. It’s always a good idea to consult the most up-to-date official documentation.

VPCs Virtual private clouds (VPCs) are easy-to-use AWS network organizers and great tools for organizing your infrastructure. Because it’s so easy to isolate the instances in one VPC from whatever else you have running, you might want to create a new VPC for each one of your projects or project stages. For example, you might have one VPC for early application development, another for beta testing, and a third for production (see Figure 2.1). Also read this topic: Introduction to Cloud Computing and AWS -1 Adding a simple VPC that doesn’t incorporate a NAT gateway (https://docs.aws.amazon .com/AmazonVPC/latest/UserGuide/vpc-nat-gateway.html) or VPN access (https://docs .aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_VPN.html) won’t cost you anything. You’ll learn much more about all this in Chapter 4, “Amazon Virtual Private Cloud.” Tenancy When launching an EC2 instance, you’ll have the opportunity to choose a tenancy model. The default setting is shared tenancy, where your instance will run as a virtual machine on a the physical server that’s concurrently hosting other instances. Those other instances might well be owned and operated by other AWS customers, although the possibility of any kind of insecure interaction between instances is remote. To meet special regulatory requirements, your organization’s instances might need an extra level of isolation. The Dedicated Instance option ensures that your instance will run on its own dedicated physical server. This means that it won’t be sharing the server with resources owned by a different customer account. The Dedicated Host option allows you to actually, identify and control the physical server you’ve been assigned to meet more restrictive licensing or regulatory requirements. Naturally, dedicated instances and dedicated hosts will cost you more than instances using shared tenancy. Exercise 2.1 will guide you through the launch of a simple EC2 Linux instance. Exercise 2 .1 Launch an EC2 Linux Instance and Log in Using SSH

1. From the EC2 Dashboard, click to launch a new instance and select a Linux AMI and instance type. Remember, the t2.micro is Free Tier–eligible if your AWS account is still within its first year.
2. Explore the Configure Instance Details, Add Storage, and Add Tags pages—although the default settings should work fine.
3. On the Configure Security Group page, make sure there’s a rule permitting incoming SSH (port 22) traffic. It should be there by default.
4. Before letting you launch the instance, AWS will require you to select—or create—a key pair. Follow the instructions.
5. Once the instance is launched, you can return to the Instances Dashboard to wait until everything is running properly.
6. Click the Actions pull-down and then the Connect item for instructions on how to connect to the instance from your local machine. Then connect and take a look at your virtual cloud server.

In Exercise 2.2, you’ll see how changing an instance’s type works. Exercise 2 . 2 Assess the Free Capacity of a Running Instance and Change Its Instance Type

1. With an instance running, open the Instances Dashboard. Select the instance you’re interested in and click the Monitoring tab in the bottom half of the screen. That’s a good place to see what percentage of compute and network resources you’ve been using over the past hours or weeks. Now pretend that your instance is nearly maxed out and change the instance type as follows.
2. Stop the instance. (Remember, your public IP address might be different when you start up again.)
3. From the Actions drop-down, click Instance Settings and then Change Instance Type. Select a new type.
4. Restart the instance and confirm that it’s running properly.

Configuring Instance Behavior You can optionally tell EC2 to execute commands on your instance as it boots by pointing to user data in your instance configuration (this is sometimes known as bootstrapping). Whether you specify the data during the console configuration process or by using the –user-data value with the AWS CLI, you can have script files bring your instance to any desired state. User data can consist of a few simple commands to install a web server and populate its web root, or it can be a sophisticated script setting the instance up as a working node within a Puppet Enterprise–driven platform. Instance Pricing Use of EC2 instances can be purchased using one of three models. For always-on deployments that you expect to run for less than 12 months, you’ll normally pay for each hour your instance is running through the on-demand model. On-demand is the most flexible way to consume EC2 resources since you’re able to closely control how much you pay by stopping and starting your instances according to your need. But, per hour, it’s also the most expensive. If you’re planning to keep the lights burning 24/7 for more than a year, then you’ll enjoy a significant discount by purchasing a reserve instance—generally over a term commitment of between one and three years. You can pay up front for the entire term of a reserve instance or, for incrementally higher rates, either partially up front and the rest in monthly charges or entirely through monthly charges. Table 2.2 gives you a sense of how costs can change between models. These estimates assume a Linux platform, all up-front payments, and default tenancy. Actual costs may vary over time and between regions. For workloads that can withstand unexpected disruption (like computation-intensive genome research applications), purchasing instances on Amazon’s Spot market can save you a lot of money. The idea is that you enter a maximum dollar-value bid for an instance type running in a particular region. The next time an instance in that region becomes available at a per-hour rate that’s equal to or below your bid, it’ll be launched using the AMI and launch template you specified. Once up, the instance will keep running either until you stop it—when your workload completes, for example—or until the instance’s per-hour rate rises above your maximum bid. You’ll learn more about the spot market and reserve instances in Chapter 12: “The Cost Optimization Pillar.” It will often make sense to combine multiple models within a single application infrastructure. An online store might, for instance, purchase one or two reserve instances to cover its normal customer demand but also allow autoscaling to automatically launch on-demand instances during periods of unusually high demand. Use Exercise 2.3 to dive deeper into EC2 pricing. Exercise 2 .3 Assess Which pricing model Will Best meet the needs of a deployment Imagine that your application will need to run two always-on f1.2xlarge instances (which come with instance storage and won’t require any EBS volumes). To meet seasonal demand, you can expect to require as many as four more instances for a total of 100 hours through the course of a single year. How should you pay for this deployment? Bonus: Calculate your total estimated monthly and annual costs.

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