Ec2

Here’s a quick tip from this thread on the AWS EC2 Developer Forums. If you experience the InsufficientInstanceCapacity: Insufficient Capacity error, you’ll be glad to know there are some strategies for working around it. Justin@AWS offers this advice: There can be short periods of time when we are unable to accommodate instance requests that are targeted to a specific Availability Zone. When a particular instance type experiences unexpected demand in an Availability Zone, our system must react by shifting capacity from one instance type to another. This can result in short periods of insufficient capacity. We incorporate this data into our capacity planning and try to manage all zones to have adequate capacity at all times. The following steps will ensure that you will have the best experience launching Amazon EC2 instances when an initial insufficient capacity message is received: ...

I’ve been awaiting this feature for a long time: Shared EBS Snapshots. Here’s a brief intro to using the feature, and some cool things you can do with shared snapshots. I also offer predictions about things that will appear as this feature gains adoption among developers. How to Share an EBS Snapshot Really, it’s easy. The first thing you’ll need to know is the Account Number of the user with whom you want to share the snapshot. If you want to make the snapshot public then you don’t need this. The account number can be found in the Your Account > Account Activity page. It’s in small numbers in the top-right of the page (so small you may need to click on the image below to see it in full size): ...

If you’ve been using EC2 for anything serious then you have some code on your instances that requires your AWS credentials. I’m talking about code that does things like this: Attach an EBS volume Download your application from a non-public location in S3 Send and receive SQS messages Query or update SimpleDB All these actions require your credentials. How do you get the credentials onto the instance in the first place? How can you store them securely once they’re there? First let’s examine the issues involved in securing your keys, and then we’ll explore the available options for doing so. ...

If you use AWS’s Elastic Load Balancer to allow your EC2 application to scale, like I do, then you’ll want to know about this gotcha recently reported in the AWS forums. By all appearances, it looks like something that should be fixed by Amazon. Until it is, you can reduce (but not eliminate) your exposure to this problem by keeping a small TTL for your ELB’s DNS CNAME entry. Read on for details. ...

There are many posts about how to mount an EBS volume to your EC2 instance during the startup process. But requiring an instance to use a specific EBS volume has limitations that make the technique unsuitable for large-scale use. In this article I present a more flexible technique that uses an EBS snapshot instead. Update December 2009: Amazon released native support for automatically mounting EBS volumes created from a snapshot, as part of supporting the boot-from-EBS feature. The techniques in this article are no longer necessary. But they’re cool anyway. ...

I discovered an interesting feature of Amazon EC2 Elastic Load Balancing today: you can add an EC2 instance to more than one ELB virtual appliance. Below I demonstrate the steps I took to set up two ELBs each containing the same instance, and afterward I explain how this technique can be used to deliver different classes of service. How to Set Up One Instance Belonging to Multiple ELBs I set this up using the standard EC2 API and EC2 ELB command-line tools. First I launched an instance. I used my favorite Alestic image, the Ubuntu 8.04 Hardy Server AMI: ...

Working with virtual infrastructure is not a whole lot different than using real hardware, but it’s easy to get confused when things are different. In this article I’ll take a look at the life cycle of Amazon EC2 instances and how it differs from the traditional life cycle of real computers. Update January 2010: This article has been updated to incorporate new options introduced by the Boot-from-EBS feature. The Life Cycle of “Real” Computers By “life cycle” I mean “the different stages that a computer goes through from power-on to power-off”. This is best explained with a diagram: Real computers begin their service lives “off”. Someone hits the power button and the computers start booting up, eventually settling into a “running” state. From there they can be rebooted, hibernated, suspended, or shut-down normally. (Of course, something abnormal can happen, such as a power failure, which would cause the machine to immediately return to the “off” state. This is not represented in the diagram above.) ...

The ElasticFox Firefox extension allows you to tag EC2 instances, EBS volumes, EBS snapshots, Elastic IPs, and AMIs. ElasticFox’s tags are stored locally within Firefox, so if you use ElasticFox from more than one browser your tags from one browser are not visible in any other browser. In this article I demonstrate how to copy tags from one ElasticFox installation to another. Where Are ElasticFox Tags Stored? My article about Tagging EC2 Instances Using Security Groups shows a brief walkthrough of using ElasticFox to tag instances. Under the hood, ElasticFox stores tags in the prefs.js file within your Firefox Profile directory. But instead of poking around in there directly, take a look at Firefox’s built-in interface to these preferences. It’s the about:config screen, and you get there by typing about:config into the address bar: ...

EBS offers the ability to have a “virtual disk drive” whose lifetime is independent of any EC2 instance. You can attach EBS drives to any running instance, and any changes made to the drive will persist even after the instance is terminated. You can also set up an EBS drive to be the root filesystem for an instance - giving you the benefits of an always-on instance but without paying for it when it’s not in use - and this article shows you how to do that. I also explore how to estimate the cost savings you can achieve using this solution. ...

Update March 2012: Amazon published their own official guide to ELB’s architecture and building and testing applications that use it. The official material is very consistent with the presentation offered here, more than two and a half years prior. Elastic Load Balancing is a long-anticipated AWS feature that aims to ease the deployment of highly-scalable web applications. Let’s take a look at how it achieves elasticity, based on experience and based on the information available in the AWS forums (mainly this thread). The goal is to understand how to design and test ELB deployments properly. ...