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DOCKER

Kubernetes vs Docker Swarm

Joseph Eshiett
February 9, 2023 | 10 min read

Containers have significantly altered how businesses create, deploy, and manage their applications. Even though containers can be manually deployed and managed in small quantities, the number of containerized applications is fast increasing in most enterprises, making their scaled management unfeasible without automation.

The operational work necessary to execute container workloads and services is automated with container orchestration. To implement this, certain tools and platforms are required. There are quite a few out there, but this article will compare two of the most popular ones: Kubernetes and Docker Swarm.

What is Docker Swarm?

Docker Swarm, also known as Swarm cluster, is an orchestration management tool that runs on Docker applications and helps end-users create and deploy a cluster of Docker nodes. It comprises the following components:

  • The Swarm manager nodes provide the control plane that manages the cluster.
  • The Worker nodes, which are managed and orchestrated by the Swarm manager nodes to perform tasks.
  • The Load balancers, which are used to route requests across different services and nodes.

Advantages of Docker Swarm

It is a great container orchestration platform for managing even production workloads. Delineated below are some of its advantages.

  • It comes built into the Docker Engine, making it easy for the developers to set up and work with when building and deploying their containerized applications.
  • It provides automatic load balancing within the Docker containers.
  • It works seamlessly with the Docker tools, Docker CLI and Docker-compose.
  • Services or tools that work well with Docker can also work with it since it comes integrated with the Swarm API.

Disadvantages of Docker Swarm

Despite its advantages, there are some disadvantages that you need to know. They include:

  • It is strongly tied to the Docker API, meaning all of the commands used in Docker can be used with it. However, some functionalities, such as volume management, are limited in Swarm. This is because Swarm was designed to be a simple and efficient tool for orchestration and does not include all of the features available in standalone Docker.
  • Customization options and add-ons are limited, unlike Kubernetes, which comes customizable and allows for specifying Custom Resource Definitions (CRDs).
  • Its capabilities are less robust and it doesnt have a large community when compared with Kubernetes.

What is Kubernetes?

Initially created by Google, Kubernetes is an open source container orchestration system for automating the deployment, management, and scaling of containerized applications with the flexibility of clusters. It is commonly referred to as K8s, which originates from counting the eight letters between the “K” and the “s”.

It is made up of the control plane, which manages all resources in the cluster and assigns tasks to worker nodes that execute these tasks and run your containerized workloads.

Advantages of Kubernetes

It offers many benefits to teams looking for a robust container orchestration platform. This includes:

  • It is backed by Google and the vendor-neutral Cloud Native Computing Foundation (CNCF).
  • It offers a wide range of key functionalities, including service discovery, Ingress, load balancing, horizontal and vertical scalability, and so on.
  • It can manage large and complex workloads.
  • It is available ”as-a-Service” in public cloud platforms like Google, Microsoft, and AWS.
  • It has a large community of contributors regularly updating the code base and documentation.

Disadvantages of Kubernetes

While it offers many significant advantages, there are also some disadvantages to consider before using it. Some of them are:

  • It has a steep learning curve and specialized knowledge in managing the nodes and the different functionalities such as Pods, Namespaces, ConfigMap, etc.
  • It is too complex for managing simplistic workloads and applications, such as deploying a simple stateless website or as a documentation site.
  • The shift or migration from another orchestration platform to K8s can be quite a daunting task, as each configuration will have to be translated to a K8s object.
  • It can be challenging to utilize without proper knowledge and specialization. This lack of knowledge has caused many pending issues and a pile-up in backlogs.

Kubernetes vs Docker Swarm: Similarities & Differences

Both are container orchestration tools, which means they may have many similar features. However, each of these similarities tends to succeed in different categories. This section will cover the similarities and differences between both platforms so you can decide on the one that best suits you.

Installation and setup

  • Docker swarm: This is relatively easy to install and set up. For instance, a simple one-liner command can install the Docker engine across different Linux operating systems.
  • Kubernetes: It requires a series of manual installations and configurations to get it up and running, such as installing , a Container Runtime, and other components such as the Kubelet.

Deployment

  • Docker Swarm: Applications are deployed as services. These services are written as YAML files and are used to manage the application deployed.
  • Kubernetes: It does provide a plethora of options for configuring and deploying applications, such as Namespaces, Deployments, and StatefulSets.

Autoscaling

  • Docker Swarm: there is no autoscaling option available. Scripts may have to be written to achieve autoscaling.
  • Kubernetes: This offers autoscaling options, such as Horizontal Pod Autoscaling, to scale workloads based on triggers such as CPU utilization.

Storage

  • Docker Swarm: Persisting data in Docker is limited to three options, which are; bind mounts, volumes, and tmpfs mount for Linux systems.
  • Kubernetes: It supports storage mounts of your choice, either from local storage or as supported by your cloud provider.

Security

  • Docker Swarm: This relies on transport layer security (TLS) and RBAC to carry out access control and security related tasks. However, the RBAC doesn’t come free. You need to purchase the Docker Enterprise Edition to get this feature.
  • Kubernetes: It supports more security options, such as role-based access control (RBAC), transport layer security (TLS), third-party authentication, and audit logging.

Load balancing

  • Docker Swarm: This uses an internal DNS system to assign DNS entries to each Swarm service automatically. In addition, the Swarm manager uses internal load balancing to distribute incoming requests to the different services based on their DNS entries.
  • Kubernetes: Pods in K8s are exposed via Services which are then used for internal load balancing within the Cluster. The Service configurations can also be set to perform external load balancing. Generally, Ingress controllers such as the Edge Stack are best used for load balancing and provide a network security layer to connections made to your workloads.

Monitoring and Logging

  • Docker Swarm: While it has built-in server logs and events tools, they may not always be enough for effective monitoring. To get the most out of monitoring your workloads, third-party tools are needed.
  • Kubernetes: This comes built-in with a dashboard that provides monitoring and logging solutions right out of the box. It also supports integration with other third-party monitoring tools.

Self-healing

  • Docker Swarm: It comes with native health checks that can be used to determine the availability of services.
  • Kubernetes: With the self-healing feature, failed or faulty containers are restarted or replaced with new ones if required.

Kubernetes vs Docker Swarm: When to Use?

Both are great options for container orchestration. They are both market leaders in container management, and it can be pretty tough to decide which is good and which is not.

If your workloads are small, relatively simplistic, and easy to manage, Docker swarm could be the right choice for a start.

If your workloads are complex and require features such as service discovery, self-healing, and monitoring, Kubernetes is the right choice for you as it comes with built-in features.

Ultimately, the platform you choose depends on your individual needs, whether personal or business needs.

Kubernetes and Docker Swarm FAQs

  • Is Docker Swarm suitable for orchestrating production workloads? — Running a swarm cluster in production has proven to orchestrate workloads successfully.
  • Is Docker Swarm becoming deprecated? — It is not being deprecated and is still a viable option for orchestrating multiple workloads.
  • Do you have to run everything on Kubernetes? — Not everything has to be run using K8s. To best meet your demands, it’s important to find a balance between in-cluster and out-of-cluster services.
  • Is running Kubernetes “expensive”? — Depending on the financial stance of your organization, it can become expensive, especially when it is being adopted without any cost plans in effect, as you will have to pay for the misuse of resources.

Conclusion

This article compared two market leaders in container orchestration.

Docker Swarm is an easy-to-use orchestration tool when compared with K8s. On the other hand, Kubernetes is better suited for more complicated workloads, and the associated user base and ecosystem are larger. Nevertheless, it is essential to consider your needs and objectives to pick the right orchestration tool.