Docker Swarm vs Kubernetes: What is the Difference?

In the modern world, where it is more crucial than ever to automate the administration of application microservices, workload orchestration of containers and container orchestration have become the bedrock of scalability, portability, and efficiency.  Kubernetes and Docker Swarm remain top competitive tools in this area as they serve almost the same functions but the operational frameworks of the two allow each tool to be used for specific intended purposes.

In this article, we will compare the differences between Docker Swarm and Kubernetes, learn about their architecture, and explore their features, including scalability, load balancing, community support, etc.

What are Containers?

In DevOps, the containers are a standard approach to aggregate the applications with all their dependencies so that they can be moved seamlessly to different runtime environments. Such containers are less heavy and quicker to deploy than virtual machines because they lack their operating system but instead share the host’s operating system kernel.

Example: Running a Python web application. While utilizing Docker, one can store the application code along with the Python runtime and library dependencies into one single container image. This container can easily run in any environment, be it a user’s PC application, a server, or a cloud application deployment.

Key Features of Containers

• Portable: With portability, you can “write once, run anywhere.”
• Efficiency: Uses fewer resources than virtual machines do.
• Scalability: To meet growing demand, containers can be swiftly duplicated.

Container orchestration includes deploying, scaling, networking, and managing containerized applications automatically and as single management units. As much as containers bring portability and lightweight to applications, the distribution of several containers on several hosts creates a problem.

Container orchestration is the technique that scales the applications of organizations to grow, manage, and handle a large number of users. Tools such as Kubernetes, and Docker Swarm are used to perform container orchestration.

What is Kubernetes?

Kubernetes is an open-source tool for container orchestration which was first created by Google to manage their containers. It offers automation, scalability, and robustness in managing containerized apps across several servers. Its broad use in data centers and clouds is a result of its ability to operate and manage workloads of all shapes and sizes. Kubernetes is available in a variety of distributions from independent software suppliers and hosted-on-cloud solutions from all of the main public cloud providers.

Worker nodes are compute hosts that comprise a Kubernetes cluster. A Kubernetes master oversees and manages all cluster resources, including these worker nodes. A node may be a physical, bare metal machine or a virtual machine (VM).

Kubernetes Architecture

• Master Node: Manages the cluster.

Key components: API Server, Controller Manager, Scheduler, etc. (key-value store).

• Worker Nodes: Run application containers.

Key components: Kubelet, Kube-Proxy, and container runtime (e.g., Docker, containers).

What is Docker Swarm?

Docker Swarm is Docker’s native container orchestration tool which is also open-source and has been there for a while. It integrates seamlessly with the Docker ecosystem and is known for its simplicity and ease of use. Docker Swarm uses Docker CLI for orchestration tasks and maintains cluster health with manager and worker nodes. Swarm automatically distributes incoming requests across services and can update the applications with zero downtime.

Docker Swarm Architecture

• Manager Nodes:
  • Handle cluster management tasks.
  • Manage worker nodes and perform scheduling.

• Worker Nodes: Execute tasks assigned by the manager nodes.

Docker Swarm Vs. Kubernetes: The Difference

Architecture

Kubernetes has a multi-level and complicated master-worker architecture, with the master node in charge of every component of the cluster. Each cluster should have one master node which will encapsulate three components that are called the api server, controller manager scheduler, etc. Its architecture allows the development of highly modular and extensible solutions through several add-ons and plugins, such as monitoring and logging. The architecture of Kubernetes allows it to be fault tolerant as workloads and the states of the cluster are distributed.

Docker Swarm can be classified as having a relatively simple architecture. It is made up of two types of nodes, the manager and the worker nodes, the latter being responsible for executing tasks while the managers are in charge of orchestration. Swarm also integrates with the Docker CLI for management tasks, making it very familiar to Docker users. However, it is unable to provide features like custom scheduling or extended functions due to its core structure.

Scalability

Kubernetes is an ideal container orchestrator for multi-cluster and production-type environments. It can handle numerous nodes in the order of thousands and containers in the order of millions. Its auto-scaling features on both the cluster and the applications make it suited for enterprises with high workloads.

Docker Swarm can be classified as having a moderate level of scalability. This can be used for setups for small and middle-sized structures. It can scale containers horizontally with the number of nodes, but extensive workloads or high complexities can not be handled since its architecture does not support such activities. In contrast to Kubernetes, Docker Swarm depends on other tools or human involvement for scaling because it lacks auto-scaling functionality.

Deployment

To deploy applications on Kubernetes, it is necessary to generate YAML manifests that detail the expected states of deployments, services, and other resources. In terms of configuration, this makes it very clear in intention, however, it is rather challenging for the new users. Kubernetes also provides support for rolling updates and rollbacks, allowing users to make updates to their applications without any considerable downtime.

On the other hand, in Docker Swarm, the approach is simpler. Developers are using Docker Compose files, which are quite familiar to Docker users. These files are self-contained; they contain all the needed services, networks, and volumes. With Swarm, deployment is also faster and less error-prone, thus, do not pose significant challenges to beginners. There are also rolling updates with Docker Swarm, but canary or blue-green deployments are not available.

Load Balancing

Kubernetes load balancers are also robust. It deploys Service objects and Ingress controllers that can help share workloads across the nodes. Additionally, since services can define the routing rules, Kubernetes links the incoming workloads to the required services. Also, the cloud provider’s load balancer can be effectively utilized as Kubernetes can be integrated with ease.

Docker Swarm takes the vice of load balancing to a whole new level where requests are distributed automatically to services and grouped into containers. It applies a round-robin approach which is set by default to harness load across several services.

Networking

Kubernetes utilizes an elaborate networking model that has inbuilt service discovery, communication between containers, and communication across nodes. Kubernetes relies on the Container Network Interface (CNI). CNI is a plug-and-play way to configure the network which allows the administrators to implement policies, encryption, and traffic management.

Docker Swarm in contrast uses layer networks in order to provide communication between containers in different nodes. This is an easier but less advanced solution compared to Kubernetes which offers advanced features such as network segmentation and deployable policies. Docker Swarm Networking works well for simple case scenarios and projects; however, projects with demands for networking performance and complexity may fail.

Community Support

Kubernetes has a large following and support from many sponsors such as Google, Red Hat, and Microsoft. This large sponsorship means better updates, better support, better documentation, and many third-party tools. The Kubernetes ecosystem is fast changing which makes it versatile for container orchestration tasks in the future.

Docker Swarm has a smaller community perhaps because it has not been widely used in recent years. People still believe in Docker as a whole, their interest in Swarm has decreased, and since then opted for Kubernetes because of its features.

Also Read: An Introduction to Kubernetes And Containers

Key Differences Between Docker Swarm Vs. Kubernetes

Which Container Orchestration Tool is Right for You?

Choosing the appropriate container orchestration tool is a direct function of the scale, complexity, and objectives of the project. In other words, both Kubernetes and Docker Swarm are not the same because they excel in different things.

Kubernetes is suitable for these scenarios because the deployments are large in scale, the applications themselves are production grade or the working environment is highly dynamic. This is bolstered by its features such as automatic scaling, fault isolation, and custom scheduling which are advanced and required by enterprises and cloud-native deployments.

Docker Swarm is however ideal for individualized smaller deployments, development environments, or for teams that prefer an uncomplicated, faster deployment process. Its integration with docker is tight-coupled and user-friendly so that the developers do not get too involved in the infrastructure setup but more on the actual application creation.

Also Read: Top 60+ Kubernetes Interview Questions and Answers

Conclusion

Whether to select Kubernetes or Docker Swarm relies on your project scope, the nature of the application, and specific use requirements. The clear strength of Kubernetes is its flexibility and scalability which are required of applications given such enterprise level. However, Docker Swarm in light of the development requirements requires smaller deployments that can easily and quickly be set up. Learn about these architectures in detail with the Certificate Program in Application Development offered by Hero Vired and also get a professional certification.

In the end, it all comes down to what your team is well versed in and what the project requires. You can choose the most effective container orchestration technique once you comprehend the functional diversities and advantages of both tools.