Architecting on AWS – Design for Graceful Service Degradation

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 for 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.
AWS Route 53 Primary DNS Record Set
We then set the routing policy to failover with a record type to Primary. This advices 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 recordset 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.
AWS S3 Static 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.
AWS Route 53 Secondary DSN Record Set

In summary

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 website 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.

Avatar

Written by

Christian Petters

As a Solutions Architect, Christian is helping organisations to find the most appropriate solution to address their unique business problems. He is passionate about the opportunities that are provided by modern cloud services and covers topics in AWS and MS Azure with a particular focus on Microsoft technologies.


Related Posts

Amanda Cross
Amanda Cross
— January 7, 2021

New Content: AWS Terraform, Java Programming Lab Challenges, Azure DP-900 & DP-300 Certification Exam Prep, Plus Plenty More Amazon, Google, Microsoft, and Big Data Courses

This month our Content Team continues building the catalog of courses for everyone learning about AWS, GCP, and Microsoft Azure. In addition, this month’s updates include several Java programming lab challenges and a couple of courses on big data. In total, we released five new learning...

Read more
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • Machine Learning
  • programming
Avatar
Stuart Scott
— December 17, 2020

Where Should You Be Focusing Your AWS Security Efforts?

Another day, another re:Invent session! This time I listened to Stephen Schmidt’s session, “AWS Security: Where we've been, where we're going.” Amongst covering the highlights of AWS security during 2020, a number of newly added AWS features/services were discussed, including: AWS Audit...

Read more
  • AWS
  • AWS re:Invent
  • cloud security
Joe Nemer
Joe Nemer
— December 4, 2020

AWS re:Invent: 2020 Keynote Top Highlights and More

We’ve gotten through the first five days of the special all-virtual 2020 edition of AWS re:Invent. It’s always a really exciting time for practitioners in the field to see what features and services AWS has cooked up for the year ahead.  This year’s conference is a marathon and not a...

Read more
  • AWS
  • AWS Glue Elastic Views
  • AWS re:Invent
Bryony Harrower
Bryony Harrower
— November 6, 2020

WARNING: Great Cloud Content Ahead

At Cloud Academy, content is at the heart of what we do. We work with the world’s leading cloud and operations teams to develop video courses and learning paths that accelerate teams and drive digital transformation. First and foremost, we listen to our customers’ needs and we stay ahea...

Read more
  • AWS
  • Azure
  • content roadmap
  • GCP
Joe Nemer
Joe Nemer
— October 25, 2020

Excelling in AWS, Azure, and Beyond – How Danut Prisacaru Prepares for the Future

Meet Danut Prisacaru. Danut has been a Software Architect for the past 10 years and has been involved in Software Engineering for 30 years. He’s passionate about software and learning, and jokes that coding is basically the only thing he can do well (!). We think his enthusiasm shines t...

Read more
  • AWS
  • careers
  • champions
  • upskilling
Joe Nemer
Joe Nemer
— October 14, 2020

New Content: AWS Data Analytics – Specialty Certification, Azure AI-900 Certification, Plus New Learning Paths, Courses, Labs, and More

This month our Content Team released two big certification Learning Paths: the AWS Certified Data Analytics - Speciality, and the Azure AI Fundamentals AI-900. In total, we released four new Learning Paths, 16 courses, 24 assessments, and 11 labs.  New content on Cloud Academy At any ...

Read more
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • Machine Learning
  • programming
Joe Nemer
Joe Nemer
— September 15, 2020

New Content: Azure DP-100 Certification, Alibaba Cloud Certified Associate Prep, 13 Security Labs, and Much More

This past month our Content Team served up a heaping spoonful of new and updated content. Not only did our experts release the brand new Azure DP-100 Certification Learning Path, but they also created 18 new hands-on labs — and so much more! New content on Cloud Academy At any time, y...

Read more
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • Machine Learning
  • programming
Joe Nemer
Joe Nemer
— August 28, 2020

AWS Certification Practice Exam: What to Expect from Test Questions

If you’re building applications on the AWS cloud or looking to get started in cloud computing, certification is a way to build deep knowledge in key services unique to the AWS platform. AWS currently offers 12 certifications that cover major cloud roles including Solutions Architect, De...

Read more
  • AWS
  • AWS Certifications
Patrick Navarro
Patrick Navarro
— August 25, 2020

Overcoming Unprecedented Business Challenges with AWS

From auto-scaling applications with high availability to video conferencing that’s used by everyone, every day —  cloud technology has never been more popular or in-demand. But what does this mean for experienced cloud professionals and the challenges they face as they carve out a new p...

Read more
  • AWS
  • Cloud Adoption
  • digital transformation
Avatar
Andrew Larkin
— August 18, 2020

Constant Content: Cloud Academy’s Q3 2020 Roadmap

Hello —  Andy Larkin here, VP of Content at Cloud Academy. I am pleased to release our roadmap for the next three months of 2020 — August through October. Let me walk you through the content we have planned for you and how this content can help you gain skills, get certified, and...

Read more
  • alibaba
  • AWS
  • Azure
  • content roadmap
  • Content updates
  • DevOps
  • GCP
  • Google Cloud
  • New content
Alisha Reyes
Alisha Reyes
— August 5, 2020

New Content: Alibaba, Azure AZ-303 and AZ-304, Site Reliability Engineering (SRE) Foundation, Python 3 Programming, 16 Hands-on Labs, and Much More

This month our Content Team did an amazing job at publishing and updating a ton of new content. Not only did our experts release the brand new AZ-303 and AZ-304 Certification Learning Paths, but they also created 16 new hands-on labs — and so much more! New content on Cloud Academy At...

Read more
  • AWS
  • Azure
  • DevOps
  • Google Cloud Platform
  • Machine Learning
  • programming
Alisha Reyes
Alisha Reyes
— July 16, 2020

Blog Digest: Which Certifications Should I Get?, The 12 Microsoft Azure Certifications, 6 Ways to Prevent a Data Breach, and More

This month, we were excited to announce that Cloud Academy was recognized in the G2 Summer 2020 reports! These reports highlight the top-rated solutions in the industry, as chosen by the source that matters most: customers. We're grateful to have been nominated as a High Performer in se...

Read more
  • AWS
  • Azure
  • blog digest
  • Certifications
  • Cloud Academy
  • OWASP
  • OWASP Top 10
  • Security
  • VPCs