Aws

AWS recently added support for receiving Simple Notification Service notifications when S3 loses a Reduced Redundancy Storage S3 object. This raises a number of questions: What the heck does that even mean? Why would I want to do that? Under what conditions does it make financial sense to do that? Let’s take a look at these questions, and we’ll also do a bit of brainstorming (please participate!) to design a service that puts it all together. ...

Thanks to reader Ewout and his comment on my article How to Keep Your AWS Credentials on an EC2 Instance Securely for suggesting an additional method of transferring credentials: via a snapshot. It’s similar to burning credentials into an AMI, but easier to do and less prone to accidental inclusion in the application’s AMI. Read on for a discussion of how to implement this technique. How to Store AWS Credentials on an EBS Snapshot This is how to store a secret on an EBS snapshot. You do this only once, or whenever you need to change the secret. ...

Dynamic infrastructure can be a pain to accommodate in applications. How do you keep track of the set of web servers in your dynamically scaling web farm? How do your apps keep up with which server is currently running what service? How can applications be written so they don’t need to care if a service gets moved to a different machine? There are a number of techniques available, and I’m happy to share implementation code for one that I’ve found useful. ...

This is a true story about a lot of data. The cast of characters is as follows: The Protagonist: Me. The Hero: Jets3t, a Java library for using Amazon S3. The Villain: Decisions made long ago, for forgotten reasons. Innocent Bystanders: My client. Once Upon a Time… Amazon S3 is a great place to store media files and allows these files to be served directly from S3, instead of from your web server, thereby saving your server’s network and CPU for more important tasks. There are some gotchas with serving files directly from S3, and it is these gotchas that had my client locked in to paying for bandwidth and CPU to serve media files directly from his web server. ...

At long last, the most oft-requested feature for EC2’s Elastic Load Balancer is here: session affinity, also known as “sticky sessions”. What is session affinity? Why is this feature in such high demand? How can it be used with existing applications? Let’s take a look at these questions. But first, let’s explore what a session is - then we’ll cover why we want it to be sticky, and what ELB’s sticky session limitations are. [To skip directly to an explanation of how to use ELB sticky sessions, go toward the bottom of the article.] ...

You may know that Amazon Web Services Reserved Instances have some gotchas. One of these gotchas is that the availability zone in which the reservation is purchased cannot be changed. So if you need to use an instance in a different availability zone (e.g. if you hit InsufficientCapacity errors*) than your reservation, you’re out of luck - and you end up paying the on-demand price. Today at CloudConnect I chatted with Jeremy Edberg of Reddit and Joe Arnold of Cloudscaling, and we had an insight: there’s a workaround. Read on for more details. ...

This is one of the coolest uses of Amazon’s ELB I’ve seen yet. Check out James Elwood’s article. You may know that you can’t serve more than one SSL-enabled domain on a single EC2 instance. Okay, you can but only via a wildcard certificate (limited) or a multi-domain certificate (hard to maintain). So you really can’t do it properly. Serving multiple SSL domains is one of the main use cases behind the popular request to support multiple IP addresses per instance. ...

S3 has an “eventual consistency” model, which presents certain limitations on how S3 can be used. Today, Amazon released an improvement called “read-after-write-consistency” in the EU and US-west regions (it’s there, hidden at the bottom of the blog post). Here’s an explanation of what this is, and why it’s cool. What is Eventual Consistency? Consistency is a key concept in data storage: it describes when changes committed to a system are visible to all participants. Classic transactional databases employ various levels of consistency, but the golden standard is that after a transaction commits the changes are guaranteed to be visible to all participants. A change committed at millisecond 1 is guaranteed to be available to all views of the system - all queries - immediately thereafter. ...

Recently I answered a question on the EC2 forums about how to give third parties access to EC2 instances. I noticed there’s not a lot of info out there about how to work with contractors, consultants, or even internal groups to whom you want to grant access to your AWS account. Here’s how. First, a Caveat Please be very selective when you choose a contractor. You want to make sure you choose a candidate who can actually do the work you need - and unfortunately, not everyone who advertises as such can really deliver the goods. Reuven Cohen’s post about choosing a contractor/consultant for cloud projects examines six key factors to consider: ...

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: ...