Throughout our series of posts we have already seen a variety of architectural patterns that allow us to design scalable and resilient solutions using Amazon Web Services (AWS) resources. However, even the best design can have flaws and may show signs of bottlenecks over time or as the demand on your application increases. This could be caused by additional load created by an influx of additional customers using your application or an increasing amount of data that needs indexing in your relational storage tier, to only name a couple.
As the saying goes; the devil is in the detail and your service quality can degrade for a large variety of reasons. While you may not be able to predict and detect each and every potential issue through load testing, you can use a number of architectural patterns to ensure that you continue to interact with your customers or users and therefore have a higher chance of keeping them satisfied.
No matter how well you plan your design, it’s unavoidable that some dependencies or processes will live beyond the control of the calling process. A typical response to this -the Circuit Breaker Pattern – was originally described by Michael Nygard. Many sources already talk about applying the pattern in the application development space. The same concept can also be implemented in the AWS infrastructure layer.
Your key ingredients for this are the Route 53 managed DNS service in combination with Route 53 health checks. Route 53 allows you to create primary and secondary DNS record sets for a given record. This is best explained with an example.
Primary DNS record set
Imagine your web site is hosted on a number of web servers that are load balanced using an AWS Elastic Load Balancer (ELB). So in Route 53 you would create an alias record set that points to the ELB endpoint.
We then set the routing policy to failover with a record type to Primary. This advises Route 53 to only send traffic to the IP address of the configured endpoint if the associated resource status is healthy.
For this to work you also need to create a Route 53 health check and associate it within the current record set.
In its most basic configuration you would point the health check to the same target as the DNS entry. Most of today’s modern web applications, though, rely on a variety of service tiers. Therefore you may want to consider the deployment of a custom health service as mentioned in my earlier post on AutoScaling. This way, the status of all sub-services contributing to the overall user experience can be included in your web site’s overall calculation.
Secondary DNS record set
Next we need to configure the secondary record set with the IP of your failover solution. Route 53 will respond with this target when the primary is considered unhealthy. Again, in its most basic form this could just be a public S3 bucket with a static web page that is enabled for website hosting.
When setting up the static site, you need to ensure that the bucket has the same name as your domain as described above. When you finished configuring the static web site, you can jump back to Route 53 to associate the secondary DNS alias record for your domain. This time we are selecting the S3 bucket as the target.
We face many different needs in our daily work, each of which demands its own unique solution. For this reason, treat this post as nothing more than an appetizer.
AWS’s Route 53 allows for far more complex scenarios, and cascading DNS configurations allow you to combine regional, weighted and failover records to cater for a wide variety of use cases.
Your solution can also be more sophisticated than a basic static web page that is hosted on S3: you could also fail over to a secondary data center in a different region or a secondary environment that may provide a custom set of features to your site’s users.
This again may be controlled by the logic in your health reporting service in combination with your application logic. You may, for example, still be able to take orders when the warehouse service is unavailable, though you may not be able to display real time availability information. However, you will want to load an alternative web site that to notify your customers of site overloads. The combination of an intelligent application and infrastructure design can also ensure that existing customers with an active transaction (e.g. a full shopping basket) can continue to check-out, while new visitors to the site are asked for a bit of patience.
As mentioned before, every solution is different. Therefore it is important for you to understand the capabilities offered by modern Cloud offerings. This way you can consider solutions that are beyond the limitations of your traditional infrastructure services. Start exploring our rich training content on CloudAcademy to get ahead of the game and learn more about the features and services provided by AWS.
WaitCondition Controls the Pace of AWS CloudFormation Templates
AWS's WaitCondition can be used with CloudFormation templates to ensure required resources are running.As you may already be aware, AWS CloudFormation is used for infrastructure automation by allowing you to write JSON templates to automatically install, configure, and bootstrap your ...
The 9 AWS Certifications: Which is Right for You and Your Team?
As companies increasingly shift workloads to the public cloud, cloud computing has moved from a nice-to-have to a core competency in the enterprise. This shift requires a new set of skills to design, deploy, and manage applications in the cloud.As the market leader and most mature p...
Two New EC2 Instance Types Announced at AWS re:Invent 2018 – Monday Night Live
The announcements at re:Invent just keep on coming! Let’s look at what benefits these two new EC2 instance types offer and how these two new instances could be of benefit to you. If you're not too familiar with Amazon EC2, you might want to familiarize yourself by creating your first Am...
Google Cloud Certification: Preparation and Prerequisites
Google Cloud Platform (GCP) has evolved from being a niche player to a serious competitor to Amazon Web Services and Microsoft Azure. In 2018, research firm Gartner placed Google in the Leaders quadrant in its Magic Quadrant for Cloud Infrastructure as a Service for the first time. In t...
Understanding AWS VPC Egress Filtering Methods
In order to understand AWS VPC egress filtering methods, you first need to understand that security on AWS is governed by a shared responsibility model where both vendor and subscriber have various operational responsibilities. AWS assumes responsibility for the underlying infrastructur...
S3 FTP: Build a Reliable and Inexpensive FTP Server Using Amazon’s S3
Is it possible to create an S3 FTP file backup/transfer solution, minimizing associated file storage and capacity planning administration headache?FTP (File Transfer Protocol) is a fast and convenient way to transfer large files over the Internet. You might, at some point, have conf...
Microservices Architecture: Advantages and Drawbacks
Microservices are a way of breaking large software projects into loosely coupled modules, which communicate with each other through simple Application Programming Interfaces (APIs).Microservices have become increasingly popular over the past few years. The modular architectural style,...
What Are Best Practices for Tagging AWS Resources?
There are many use cases for tags, but what are the best practices for tagging AWS resources? In order for your organization to effectively manage resources (and your monthly AWS bill), you need to implement and adopt a thoughtful tagging strategy that makes sense for your business. The...
How to Optimize Amazon S3 Performance
Amazon S3 is the most common storage options for many organizations, being object storage it is used for a wide variety of data types, from the smallest objects to huge datasets. All in all, Amazon S3 is a great service to store a wide scope of data types in a highly available and resil...
How to Optimize Cloud Costs with Spot Instances: New on Cloud Academy
One of the main promises of cloud computing is access to nearly endless capacity. However, it doesn’t come cheap. With the introduction of Spot Instances for Amazon Web Services’ Elastic Compute Cloud (AWS EC2) in 2009, spot instances have been a way for major cloud providers to sell sp...
What are the Benefits of Machine Learning in the Cloud?
A Comparison of Machine Learning Services on AWS, Azure, and Google CloudArtificial intelligence and machine learning are steadily making their way into enterprise applications in areas such as customer support, fraud detection, and business intelligence. There is every reason to beli...
How to Use AWS CLI
The AWS Command Line Interface (CLI) is for managing your AWS services from a terminal session on your own client, allowing you to control and configure multiple AWS services.So you’ve been using AWS for awhile and finally feel comfortable clicking your way through all the services....