Many organizations have realized that they can scale more easily and deploy updates and features fast by building applications in containers. You can replicate containers across multiple servers and clouds to ensure that your application scales up or down in response to demand and responds to failures seamlessly.
If you are considering containerized applications, you will need a container orchestration tool to help you manage the creation and operation of your containers across a variety of servers and cloud providers. Kubernetes is a popular option enabling DevOps teams to deploy and operate containers via software commands and APIs, providing them with complete control over distributed applications.
Unfortunately, many Kubernetes users do not get the best out of the platform because they do not design their applications to take advantage of Kubernetes's best features. If you want to manage a distributed system at scale and get the very best out of your container platform, follow this guide to learn the best practices for developing applications for Kubernetes.
1. Think Smaller
Application teams designing software for containers need to think small. This shift in thinking is a big challenge.
Most traditional architects, software engineers, and developers are used to looking at a software system in its entirety. They want to understand how it can meet business needs, how it can maintain smooth end-to-end operation, and – crucially – how it can function independently of other services.
To be successful with Kubernetes, application teams must learn to break down software into small components and to understand their complex inter-dependencies.
- Keep each component of an application as simple as possible so that it is easy to replicate and scale as needed.
- Make each component as small as possible.
- Don’t assume that components should be defined by logical barriers. Go smaller if you can.
It might sound counterintuitive, but this approach makes for smooth software replication, easier testing, smoother integration into CI/CD pipelines (Continuous Integration / Continuous Delivery), and, importantly, more straightforward maintenance.
A greater number of smaller components means you will have more containers and integration points, adding some complexity. However, Kubernetes is designed to simplify and automate the management of large numbers of containers. You can take advantage of Kubernetes’s container orchestration features to enable you to adopt the “think smaller” approach.
By always thinking smaller, you will find it easier to track and fix container issues in the long run.
2. Use CI/CD Automation
In the first point, I mentioned CI/CD pipelines. If you are not already using or considering CI/CD pipelines as part of your container strategy, you should start now.
You will only realize the key benefits of containers and Kubernetes when you adopt CI/CD. For example:
- Scale-up and down responsively.
- Develop, test, and deploy in production in multiple environments.
- Test in production and continually improve.
Kubernetes by itself doesn’t deliver these benefits. You need the right workflow and integrated tooling to enable CI/CD in your organization.
Ensure you choose tooling that integrates with Kubernetes and that you can trace development and testing across each environment and to each container.
Use automation to quickly, consistently, and safely take updates and new features from development to testing and to production via containers, with continuous monitoring, rolling upgrades, and rollback where necessary.
These methods will help you to reduce time-to-market and de-risk your product cycles.
3. Keep Container Images Lightweight
Ensure your container images are lightweight, meaning they use as little storage space and memory as possible.
Lightweight container images that share layers are quicker to transfer and deploy. Kubernetes can start and stop lightweight container images faster than heavy ones. This helps autoscaling and disaster recovery to be as fast as possible.
Lightweight container images also use less storage space so your servers or cloud can handle more containers at once.
To keep your container images lightweight, follow these guidelines.
Use Complete Base Images
Ensure that your base container images include everything you need while remaining as small as possible. By shifting functionality from your nested container images to your base images where they can share base functionality, each nested container in the base image can be smaller.
Include all long-running installation processes in your base images and allow the Ambler configurations to run when a system is booting up. This is faster than running install scripts in each container when they boot up.
Use Multi-Stage Docker Builds
Combine multiple layers into one with multi-stage Docker builds. Each layer in your Docker build process requires overhead in the Docker operating system. The fewer layers you have, the smaller the management overhead. Streamlining your layers into bigger multi-stage layers can help reduce the size of your final container image.
4. Validate Third-Party Images and DIY If You Need To
You can accelerate development by using existing container images available in open source communities, instead of building them from scratch yourself. However, you must check and validate that these third-party images do not compromise your security or overall image size.
Using third-party images can introduce security vulnerabilities. You don’t necessarily know every configuration in the image so you can’t control the level of risk involved. Check, test, and validate as much as you can.
Using third-party images can inflate your image size. Some third-party images contain unnecessary things that you don’t need for your particular application. You can sometimes reduce complexity and save a lot of space by building your own image running only the bare minimum software configuration that you need.
5. Plan For Observability, Telemetry, And Monitoring From The Start
When you build and deploy a distributed system, it becomes more difficult to maintain a clear picture of what is happening across every location, container, and service. Observability teams must rely on telemetry and monitoring to understand application health, performance, and security. If you try to account for this late in your development process, you will likely face significant challenges retrofitting solutions into your applications and containers, introducing delays and extra costs.
Plan for observability, telemetry, and monitoring from the beginning. This will reduce development time as well as bring the following benefits.
- You can reduce the overall size of your image.
- You can improve the reliability of telemetry and monitoring.
- You can fully control how information flows between your containers.
- You can instrument the information you know will be needed for observability, making it easier to track, identify, and respond to issues.
6. Consider Stateless Applications
You can improve Kubernetes’s performance when starting and stopping containers by using stateless applications.
Kubernetes can start and stop containers very quickly when they operate independently. However, Kubernetes is much slower when it needs to trace and reference previous processes or information – especially in a complex distributed system.
You can use stateless applications and processes to maximize independence and minimize how often Kubernetes needs to reference previous processes and information.
You cannot always go stateless. Sometimes, stateful operations are necessary to the flow of information in a system or preferable because of their benefits to the user experience.
However, if you aim for statelessness as a primary goal from the outset you will maximize Kubernetes performance.
7. Consider Interoperability
If your containers have a complex set of dependencies and can only function under certain system properties, you will find it difficult to manage. Containerized applications work best when each container can operate independently of the others. This requires each container to have strong interoperability with its surrounding environment.
During planning and development, make interoperability a primary objective in your software design. You will need to consider:
This is a significant challenge but one worth overcoming if you want to make the most of Kubernetes and your distributed system.
Kubernetes is a great platform that provides DevOps teams with effective container management. However, to get the full value from your investment in Kubernetes and a distributed architecture, you must design your application and workflows to take advantage of it.
The best performance, security, management, and visibility await those who understand how to leverage Kubernetes to the full.