To simplify the deployment and management of complex applications, many development teams rely on the benefits of container technology. Containers bundle dependencies into a single package. They are portable, fast, secure, scalable and easy to manage, making them the preferred choice over traditional VMs.

To scale containers, you need a container orchestration tool such as 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 organisation.

Docker Swarm

Docker Swarm is an open-source container orchestration platform built and maintained by Docker. Under the bonnet, Docker Swarm combines multiple Docker instances into a single virtual machine. A Docker Swarm cluster typically consists of three components:

• Nodes
• Services and tasks
• Load balancers

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

The benefits of Docker Swarm

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

Docker Swarm works with the Docker CLI, so there is no need to run or install a completely new CLI. It does not require any configuration changes if the system is already running within Docker. Furthermore, it works seamlessly with existing Docker tools, such as Docker Compose.

Docker Swarm vulnerabilities

Despite the advantages of using Docker Swarm, there are a few drawbacks that are worth being aware of.

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

Kubernetes

Kubernetes is an open-source container orchestration platform created by Google to manage its own containers. Kubernetes has a more complex cluster structure than Docker Swarm. It can have a builder and worker node architecture, which is further divided into pods, namespaces, config maps and other components.

The benefits of Kubernetes

Kubernetes offers numerous benefits to teams that need a robust container orchestration tool:

• It has a large open-source community supported by Google.
• It supports all operating systems.
• It is capable of supporting and managing large-scale architectures and complex workloads.
• It features automated and self-healing capabilities, which support automatic scaling.
• It features built-in monitoring and a wide range of integrations.
• All three key cloud service providers offer these services: Google, Azure and AWS.
• Thanks to its extensive community support and its ability to handle even the most complex deployment scenarios, Kubernetes is often the first choice for enterprise development teams managing microservice-based applications.

The disadvantages of Kubernetes

Despite its comprehensive feature set, Kubernetes does have a few drawbacks:

• It involves a complicated installation process and has a steep learning curve.
• You need to install separate CLI tools and learn how to use each one.
• Migrating from Docker Swarm to Kubernetes can be complex and difficult to manage.

In certain situations, Kubernetes can be overly complex and may lead to a drop in productivity.

Docker Swarm vs Kubernetes: similarities and differences

So far, we have discussed the advantages and disadvantages of each platform in general terms. We will now analyse the key differences and similarities. For both platforms, we will compare the configuration requirements, application deployment capabilities, availability and scalability, management features, security and load balancing.

Installation, configuration and learning process

Compared to Kubernetes, Docker Swarm is easy to install, and instances are generally consistent across the operating system. It is easier to learn than Kubernetes and works with the existing CLI. Configuring a Docker Swarm cluster is simpler than configuring Kubernetes.

Compared to Docker Swarm, installing Kubernetes is more complex and requires more manual work. Installation instructions may vary depending on the operating system. It can be challenging for developers to learn, as they need to familiarise themselves with a separate CLI tool.

Installing an application

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

Kubernetes offers a wider range of possibilities, such as combinations of namespaces, pods and deployments.

Availability and scalability

Docker Swarm ensures high availability, as it allows you to easily replicate microservices within it. Although it does not provide automatic scaling, Docker Swarm offers faster deployment times.

By its very nature, Kubernetes is highly available, fault-tolerant and self-healing. It also provides automatic scaling and is capable of replacing faulty pods when necessary.

Monitoring

Docker Swarm only supports monitoring via third-party applications that do not have built-in 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 tasks relating to access control.

Kubernetes supports a variety of security protocols, such as role-based access control (RBAC), SSL/TLS, secret management, policies and so on.

Load balancing

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

Kubernetes does not have an automatic load-balancing mechanism. However, Nginx Ingress can act as a load balancer for individual services within the cluster.

K3s as an alternative

Developers looking for a middle ground between the effortless simplicity of Docker Swarm and the cumbersome complexity of Kubernetes should consider a new platform: K3s. K3s eliminates the complexity of Kubernetes and offers a simpler, more accessible experience.

K3s is a small binary that implements the full Kubernetes API. Without unnecessary packages, you can quickly add functionality using third-party extensions. Lightweight and easy to use, K3s has a CNCF certificate.

Docker Swarm users who are not yet ready for a full-fledged Kubernetes deployment may find K3s to be an ideal alternative.

Which platform should I use?

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

For beginners, Docker Swarm is an easy-to-use and straightforward solution for managing containers at scale. If your company is entering the world of containers and does not need to manage complex workloads, then Docker Swarm is the right choice.

If you’re looking for a comprehensive package offering 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 the learning curve, then K3s is a good alternative.

In summary

In this article, we have examined the two primary orchestrators in the world of containers: Kubernetes and Docker Swarm. Docker Swarm is a lightweight, easy-to-use orchestration tool which, compared to Kubernetes, offers a limited range of features. In contrast, Kubernetes is complex but powerful, and provides self-healing and automatic scaling capabilities out of the box. K3s, a lightweight, CNCF-certified version of Kubernetes, may be a suitable choice if you wish to enjoy the benefits of Kubernetes without the learning curve.