Friday, December 20, 2013

May I Take Your Order? Our Menu of AWS Services

This is the second post in my series about how we use Amazon Web Services at Church on the Move to create highly available scaling websites. In my previous post, I talked about my experience in getting involved in Amazon Web Services, and how we ended up moving toward running our websites using servers in the cloud. Today I want to give an overview of the services we use at AWS to make our auto-scaling happen.

AWS has a smorgasbord of really cool systems. Several of the systems I know very little about. Most of the ones I know little about I have no real need to use - they offer services I don't need. I'm not running complex simulations or doing massive data conversions, or any of a number of other operations that would use those services. What I do is build and maintain websites and databases, usually integrated together, with fairly complex logic that includes user authentication, CMS, file storage, etc. We have a specific combination of AWS services that we use to accomplish this, and here I will give a brief overview of what those services are. I'll go into further detail on how we use each system - and hopefully have enough information that you will be able to build a similar system for yourself.

Elastic Cloud Computing

The backbone of what we use is the Elastic Compute Cloud, or EC2. For a while I thought maybe this was the second generation of their cloud servers, and then I realized that the 2 means there are 2 C's ... why do I mention that? Because even though I'm a programmer I do have an active random thought generator. I will get back on point now.

EC2 is Amazon's cloud computing system. The main part are the EC2 instances - virtual machines that you launch and pretty much act like a physical machine. Amazon offers several tiers of EC2 instances, ranging from a "micro" instance - which costs next to nothing and actually can perform quite well on a website that doesn't get a constant stream of traffic - to very large instances that provide lots of CPU power or memory or both, but are very expensive to run. AWS bills you by the hour that the instance is running. If you launch an instance for 2 hours, you only pay for those two hours. No long term commitment, no up front costs ... unless you purchase a "reserved" instance, which basically costs a relatively small amount up front and then you pay a significantly reduced hourly rate. Once you decide you will be using AWS long term, you  should purchase reserved instances to make your experience even more inexpensive.

One of the coolest aspects of using a virtual server instead of a physical one is the fact that you're actually working in an application with a file. In the same way that a Word document can be copied, saved, moved to another computer, and kept with multiple revisions, you can do those same things with your server. You can snapshot your server, which in essence is saving a copy of your drive. The corollary of that concept is creating an image of your server which you can then use to boot up an identical server. These concepts are awesome even if you aren't duplicating your server for auto scaling - I have servers that I don't have in any kind of auto scale group, but I take snapshots of them so that if something catastrophic happens - such as a rogue script deleting my entire hard drive, or a misguided "sudo rm -fr *" command, I can mount a drive from my snapshot and repair or rebuild my server.

Simple Storage Service

Next in line is Amazon's Simple Storage Service, or S3. If you don't know why it's S3, see my above random rant. I will stay on topic here.

S3 is basically an unlimited storage space that you can put whatever you want. (Well, as long as it's a file). Unlike an EC2 instance, where if you want to have a 1.5TB drive you have to pay for all 1.5TB each month, even if you are only using 3GB, S3 only charges you for the space you use and the time you are using it. You can make areas of S3 publicly available and even serve an entire static website from S3; you can make other areas of S3 highly secure and even use their server side encryption to remain HIPPAA compliant. I don't store anything where I have to worry about HIPPAA, so I won't go into any detail about that; suffice it to say that S3 is a key player in our website architecture.

Relational Database Service

RDS is Amazon's non-character-repeating managed database service. We use their MySQL servers, but they have other engines available as well. RDS puts the management of your database server into Amazon's hands. There are pros and cons to this, which I'll get into in another post. Most of our databases are running on RDS instances.

DynamoDB

Surprisingly not named DDB, this is Amazon's NoSQL database system. NoSQL is kind of a new buzzword in the industry, popular because of its speed and ease of use. I haven't jumped on the NoSQL bandwagon, because I am very much a relational database designer, but there are times that it makes more sense to use NoSQL if you don't need the relational features. I mention it here because we have some such usage. I'll talk more about how we use DynamoDB in a future post.

Amazon Cloud Watch

Clearly an indication that Amazon was growing tired of turning their services into Acronyms, Amazon Cloud Watch is their system monitoring service. The short description is that using Cloud Watch, you can be notified when certain metric thresholds have been hit, such as CPU usage of your servers or when your RDS instance has a certain number of connections. There are far more metrics you can monitor than I will ever care about. But, besides sending you e-mails and text messages when these alarms fire, you can also have them ping a webpage or execute auto scaling actions. We have different alarms doing all four of those actions, and obviously this is a pretty strong key when it comes to auto-scaling.

Route 53

Returning to cleverly named services, Route 53 is Amazon's DNS service. Unlike the DNS service you would use with your domain at DynaDot or with the name servers you got from your shared hosting service, you do have to pay for a Route 53 domain name. But there are a lot of reasons to use it, all of which I won't go into now. I'll just say that we use Route 53 because ... I prefer it. That should be good enough. And I suggest you check it out, you'll probably prefer it too.

That concludes the list of services I'll be discussing in this series. These are the services that I am most familiar with because I deal with them on an almost daily basis. And these are the services we use to build our auto-scaling system.

Briefly, I want to mention one other cool service called Elastic Beanstalk. This is Amazon's managed scaling solution. Basically everything I am going to cover in this series is done automatically if you use Elastic Beanstalk; however, I personally tried using this and didn't care for it. I prefer to have full control over my system's scaling activities and the servers that they run on. You may actually find Elastic Beanstalk fits your mold better; if it does, that's fantastic. It doesn't cost any more than an equivalent environment you built yourself.

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