Docker Swarm vs Kubernetes: how to choose a container orchestration tool

To simplify deploying and managing complex applications, many development teams rely on the benefits of container technology. Containers group dependencies into one package. They are portable, fast, secure, scalable, and easy to manage, making them the primary choice over traditional VMs.

To scale containers, you need a container orchestration tool like Docker Swarm or Kubernetes. Both tools provide a framework for managing multiple containers, and each has its own strengths, weaknesses, and specific focus.

In this article, we compare Docker Swarm and Kubernetes to help you decide which container orchestration tool is best for your organization.

Docker Swarm

Docker Swarm is an open source container orchestration platform built and maintained by Docker. Under the hood, Docker Swarm converts multiple Docker instances into a single virtual host. A Docker Swarm cluster usually contains three items:

1. Nodes
2. Services and tasks
3. Load balancers

Nodes are individual instances of the Docker engine. Nodes control your cluster and manage the containers used to run your services and tasks. Docker Swarm clusters also include load balancing to route requests across nodes.

Advantages of Docker Swarm

Docker Swarm is straightforward to install, lightweight and easy to use. If you are unfamiliar with container orchestration, you may find that Docker Swarm takes less time to understand than more complex orchestration tools. Unlike other tools that require manual processes, Docker Swarm provides automated load balancing within the Docker containers.

Docker Swarm works with the Docker CLI, so there is no need to run or install an entirely new CLI. It does not require configuration changes if your system is already running inside Docker. Plus, it works seamlessly with existing Docker tools such as Docker Compose.

Docker Swarm weaknesses

Despite its benefits, there are a few disadvantages of using Docker Swarm that you should be aware of.

First, it is lightweight and tied to the Docker API, which limits functionality compared to Kubernetes. Likewise, Docker Swarm’s automation capabilities are not as robust as those offered by Kubernetes.

Kubernetes

Kubernetes is an open source container orchestration platform that Google created to manage their own containers. Kubernetes has a more complex cluster structure than Docker Swarm. It can have a builder and worker nodes architecture divided further into pods, namespaces, config maps, and more.

Advantages of Kubernetes

Kubernetes offers a wide range of benefits to teams who need a robust container orchestration tool:

• It has a large open source community, backed by Google.
• It supports every operating system.
• It can sustain and manage large architectures and complex workloads.
• It is automated and has a self-healing capacity that supports automatic scaling.
• It has built-in monitoring and a wide range of integrations available.
• It is offered by all three key cloud providers: Google, Azure, and AWS.

Because of its broad community support and ability to handle even the most complex deployment scenarios, Kubernetes is often the number one choice for enterprise development teams managing microservice-based applications.

Disadvantages of Kubernetes

Despite its comprehensive feature set, Kubernetes also has a few drawbacks:

• It has a complex installation process and a steep learning curve.
• It requires you to install separate CLI tools and learn each of them.
• The transition from Docker Swarm to Kubernetes can be complicated and difficult to manage.

In some situations, Kubernetes can be overly complicated and lead to a loss of productivity.

Docker Swarm vs Kubernetes: similarities and differences

So far, we have discussed the pros and cons of each platform in general. Now, let’s analyze their key differences and similarities. For both tools, we will compare setup requirements, app deployment capabilities, availability and scaling, monitoring features, security, and load balancing.

Installation, configuration, and learning curve

Docker Swarm is simple to install compared to Kubernetes, and instances are usually consistent across the OS. It is easier to learn than Kubernetes, and works with the existing CLI. Configuring a cluster in Docker Swarm is easier than configuring Kubernetes.

Compared to Docker Swarm, Kubernetes has a more complex installation and requires more manual effort. The installation instructions can differ for each OS. Developers can find it challenging to learn, the they must get up to speed using a separate CLI tool.

Application deployment

Docker Swarm applications are services or microservices you can deploy using YAML files or Docker Compose.

Kubernetes provides a broader range of options, such as a combination of namespaces, pods, and deployments.

Availability and scaling

Docker Swarm provides high availability as you can easily duplicate the microservices within it. Although it doesn’t provide automatic scaling, Docker Swarm does have a faster deployment time.

Kubernetes is by nature highly available, fault tolerant, and self-healing. It also provides automatic scaling and can replace faulty pods if needed.

Monitoring

Docker Swarm supports monitoring only through third-party applications without in-built monitoring mechanisms.

In contrast, Kubernetes has built-in monitoring and supports integration with third-party monitoring tools.

Security

Docker Swarm relies on transport-layer security (TLS) to carry out access control-related tasks.

Kubernetes supports multiple security protocols such as role-based access control (RBAC), SSL/TLS, secrets management, policies, and more.

Load balancing

Docker Swarm supports automatic load balancing and uses DNS under the hood.

Kubernetes does not have an automatic load-balancing mechanism. However, Nginx Ingress can serve as the load balancer for each service within the cluster.

K3s as an alternative

Developers looking for a middle ground between Docker Swarm’s lightweight simplicity and Kubernetes’ heavy complexity, might want to consider a new platform, K3s. K3s eliminates the complexity of Kubernetes and provides a lighter, more accessible experience.

K3s is a tiny binary that implements the complete Kubernetes API. Without unnecessary packages, you can add functionality quickly using third-party add-ons. Lightweight and easy to use, K3s is Cloud Native Computing Foundation (CNCF) certified.

Docker Swarm users who aren’t ready for full-on Kubernetes might find K3s an ideal alternative.

Which platform should you use?

Both Kubernetes and Docker Swarm serve specific use cases. Which one is best for you depends on your team’s needs.

For beginners, Docker Swarm is an easy-to-use and simple solution to manage containers at scale. If your company is moving to the container world and does not have complex workloads to manage, then Docker Swarm is the right choice.

If you want a complete package with monitoring, security features, self-healing, high availability, and absolute flexibility for tricky or complex projects, then Kubernetes is the right choice.

If you need all the capabilities of Kubernetes but are put off by its learning curve, then K3s is a good alternative.

Conclusion

In this article, we explored the two primary orchestrators of the container world, Kubernetes and Docker Swarm. Docker Swarm is a lightweight, easy-to-use orchestration tool with limited offerings compared to Kubernetes. In contrast, Kubernetes is complex but powerful and provides self-healing, auto-scaling capabilities out of the box. K3s, a lightweight form of Kubernetes certified by CNCF, can be the right choice if you want the benefits of Kubernetes without all of the learning overhead.

Which orchestration tool is best for you depends on your business needs. Consider your team’s objectives and experience carefully before making a choice. No matter which platform you choose, you will be well-positioned to scale and manage your containerized applications. Sign up for a free CircleCI plan to start exploring the benefits of automation and container orchestration for your projects.