What Are Cloud-Native Applications?
While there isn’t a universal definition for cloud-native applications, some common principles characterize them. Cloud technologies are used to create applications that are easier to manage and scale. The cloud is about giving the business flexibility without sacrificing speed.
In this post, I want to explore the characteristics of cloud native software and a path toward cloud native development.
What Is a Cloud-Native Application?
Most modern organizations are building applications with either a hybrid or cloud-first strategy in mind. Applications are built to scale quickly, anticipating success as the next hyper-growth unicorn, similar to Netflix. While few will reach the size Netflix did, the principles behind its architecture are nevertheless widely applicable.
The most crucial aspect of a cloud-native system is loose coupling. This is typically associated with microservices. You break a massive, unwieldy, monolithic application into smaller units that are easier to develop, understand, and maintain. Packaging these applications as containers works wonderfully, as it makes distribution consistent and convenient. Kubernetes is the clear leader in the space, albeit not the only option.
Lastly, a cloud-native application typically runs in the cloud, but, hybrid workloads are becoming more common. One way or the other, you provision the exact infrastructure your application requires, controlling every detail and increasing flexibility.
This flexibility comes at a cost, though, as things become too complex to manage by hand. A lot of automation is needed to handle the complexity. Using Infrastructure as Code (IAC) is paramount to managing all the different pieces.
Why Would Somebody Want to Build a Cloud-Native Application?
After thinking about the term “cloud-native,” a different question arises: why would you need it?
- Scalability: Scaling fast is a requirement for many organizations. Many have found out the hard way how challenging it is to scale an organization based on a legacy monolith.
- Fast iteration: Small, easily deployable components leveraging cloud infrastructure are ideal for quick iteration. As Accelerate shows, lead time is a good predictor of high performance.
- Resilience: Users have high expectations for modern applications. You can’t shut them down for maintenance at 5 p.m. Users across the globe assume your application will be online at all times.
- Elasticity: Many applications don’t have predictable traffic patterns, and you want to react to them without under- or overprovisioning your infrastructure.
How Do You Get Started?
Let’s say you’ve considered your use case and decided the cloud is the ideal medium for your application. How do you get there? Few projects are truly greenfield. You likely have existing systems to consider. Do you rewrite them completely, or do you carry them as they are into the cloud (“lift and shift”)?
Context plays an important role in this decision. If you go for a lift and shift, you could miss the benefits of the cloud. A decades-old monolith isn’t going to become easier to operate just because it’s running on EKS. Conversely, a Big Bang release is risky, as you’re essentially changing everything at the same time.
Instead of a quick change, small releases reduce risk and allow you to deliver value early on. Serious cloud providers offer tools to make a transition smoother. You replace high-impact parts with newly built code and progressively isolate the older parts until they’re ready to be decommissioned. This approach is often called the strangler patternc.
Cloud-Native Is a Process As Well
Cloud development isn’t only about technology. The way you build applications makes a huge difference in the result. Are you familiar with DevOps principles? They cover culture and ways of working:
- Fast feedback loops
- Collaboration across teams and departments
- Autonomous teams
- Automation
These principles are essential to practicing continuous delivery. If you don’t integrate them into your day-to-day work, all the fancy technology will be for naught.
Designing an Application With the Cloud in Mind: The Twelve-Factor App
A cloud native system is composed of many smaller applications, often developed simultaneously by autonomous teams. Without shared guidelines, it devolves into chaos and anarchy. OK, that’s a bit of an exaggeration. Still, it’s harder to deliver a consistent experience.
The twelve-factor app is a sensible methodology to follow in this case. It’s a set of 12 principles to make applications easier to run at scale. It touches on practices like parity between environments, treating applications as disposable, or executing applications as stateless processes. It’s a good North Star to follow if you’re preparing your applications for the transition to the cloud.
Barely maintained monolithic codes will be difficult to convert without some changes. Some cloud migrations fail because people expect massive improvements without any investment on their part.
Observability Is a First-Class Citizen
There are many advantages of cloud-native applications. However, there are some downsides. For instance, if you use microservices, you’ll have many more moving parts than in a classical monolith, making it harder to assess the overall health of the system.
Observability is a crucial cross-functional requirement. It enables you to understand how your application behaves over time. If you’re building a cloud-native architecture, you should include the following elements from the beginning:
- Logging: Structured, uniform notes you collect across every layer as an event stream.
- Metrics: Systems export metrics. A centralized system aggregates them.
- Traces: You can follow a request across the boundaries of independent systems.
- User experience: Know when and how performance on the back end is affecting end users.
You don’t build observability by adding each concern separately—they have to work in unison to be effective. They need to consider the dependencies connecting different components in the system.
To the Cloud!
The cloud is an opportunity to build applications that are scalable and allow fast iteration. However, it’s not a silver bullet. Putting an application in the cloud won’t magically solve its problems. If teams don’t adapt their practices, they won’t leverage the advantages of something like AWS.
Cloud native applications need good monitoring. It’s an indispensable precondition to operate them effectively. A solution such as SolarWinds Observability SaaS (formerly known as SolarWinds Observability) helps you handle these concerns. Not building these capabilities on your own saves valuable time your engineers can spend delivering an awesome experience for your users.
This post was written by Mario Fernandez. Mario develops software for a living—then he goes home and continues thinking about software because he just can’t get enough. He’s passionate about tools and practices, such as continuous delivery. He’s been involved in front-end, back-end, and infrastructure projects.