Amazon Route53 Health Checks Available in CloudWatch

Route 53 Health Checks

Website availability is utmost important if your business depends on it. There are lots of free services (and paid services, too) to constantly monitor your site's availability and send you an email if website is not available. Some of these services offer periodic checks for every 15 minutes, some in 5, and only few support checking your site's health every 60 seconds or less.

While this sounds good, what can you do about when your site actually is down? Imagine scenario like this: it's 8pm Friday, nobody is in the office, tech support does not pick up the phone. And your website is down, totally. Yes, you received alert, even multiple alerts. Even some clients call, and your competitors rub hands.

Here's what you can do: enable Route53 health checks and host backup site in Amazon S3 (the backup site can simply say that "Sorry, we are currently experiencing technical issues; please check back later." - it is 100 times better than empty page).

If you enable DNS Failover feature and create one or more health checks, Route 53 will perform periodically either HTTP or TCP checks and switch to a secondary address (possibly a static website hosted on Amazon S3) if several consecutive checks fail.

Route53 DNS Failover Feature

Here's how AWS describe their service:

"DNS Failover feature gives you the power to monitor your website and automatically route your visitors to a backup site if it goes down."

It is fairly straight forward: you host DNS records with Amazon, and create health check on your Primary A record. You have options - either HTTP or TCP check. Once enabled, Amazon will start polling the site (e.g. www.mywebsite.com) from multiple AWS locations (you will see this traffic in your logs). Once availability is lost (and multiple checkers confirm it) the system initiates fail-over to Secondary.

Route 53 health checks may also be used in combination with Latency Based Routing, or Weighted Round Robin records to route around instance, availability zone or even region level problems.

Read how to create backup website using Route 53 DNS failover on AWS blog.

ELB Integration for DNS Failover and CloudWatch

"Route 53 DNS Failover handles all of these failure scenarios by integrating with ELB behind the scenes. Once enabled, Route 53 automatically configures and manages health checks  for individual ELB nodes. Route 53 also takes advantage of the EC2 instance health checking that ELB performs"

Yesterday AWS announced that you can see Route 53 Health Check status in CloudWatch, just like any other metrics. From here, you can create an alarm just like for any other CloudWatch metric, and you can use the alarm to trigger SNS notifications (for example, to send an email to yourself) if your endpoint goes down.

More reading:

Amazon Route 53 Adds ELB Integration for DNS Failover

Route 53 Health Checks, DNS Failover, and CloudWatch

Conclusion

Start using Route53 today - its one of the best DNS services you can get, and packs interesting feature set - geographically distributed DNS, site health checks, DNS failover, and many more. We use it in production for more than a year, and can recommend it to anyone as #1 DNS solution.