Kubernetes vs Docker Swarm – The Complete Comprehension

Container orchestration is experiencing rapid growth, kubernetes and docker swarm are the market leaders in this field. These two are considered as essential tools to deploy containers into a cluster. They have occupied a unique place in their field.

Let’s look into the details of Kubernetes and Docker Swarm before comparing or knowing the differences between these two.

Overview of Kubernetes

Kubernetes is a portable, extensible, and open-source platform for managing and containerizing workloads. It facilitates declarative configuration and automation. Kubernetes has a vast exponentially growing ecosystem. The wide availability of its services, tools, and support makes it unique and reliable. Google built it with their experience in running containers. It has got the advantage of leveraging Google’s years of experience in container management.

Overview of Docker Swarm

Docker swarm is docker’s own container Orchestration. It is a clustering and scheduling tool for Docker containers. With the help of Swarm IT developers and Administrators can establish and handle docker nodes as a single virtual system. Docker Swarm is mainly designed to work around four key instructions.  

  • It has default security features with automatically generated certificates.
  • Simple yet powerful with the excellent user experience.
  • It supports backward compatibility with existing components.
  • Docker Swarm has a ‘Resilient Zero single-point-of-failure’ architecture.

Kubernetes vs Docker Swarm

Even though both kubernetes and docker Swarm performs the same function called container Orchestration, they do have some fundamental differences in how they operate on their own style.

Below mentioned are the significant differences between these two.

Application definition:

In kubernetes, an application can be deployed by using a combination of services (or microservices), pods, and deployments. A Pod is the group of co-located containers and the atomic unit of deployment.  A Service is the external face of container workloads and integrates with DNS.

Whereas in Docker Swarm application can be deployed as a Service in Swarm cluster. YAML files are used to indicate multi-container and  Labels are used to distribute the tasks across the datacenters. Various placement preferences are used to distribute the tasks for further requirements.

Also read: RPA Overview

Installation and setup

In kubernetes installation can be done manually and it requires serious planning to make Kubernetes up and ready for running. Installation process varies from OS to OS provider to provider. Cluster configurations like which node has to take what role and IP address of a node must be known in advance in Kubernetes.

Whereas; Docker swarm is simple to install when compared to Kubernetes.  In Docker, a user is required to learn only one set of tools to build upon environment and configuration. We have great flexibility in Docker Swarm, and any new node can be allowed to join either a manager or a worker in an existing cluster.

Storage

Kubernetes provides two storage APIs. Among the two, the first one provides abstractions for individual backends, e.g. AWS EBS, NFS, folcker, and ceph. The second storage device provides an abstraction for a storage request resource. which is used to store the backends.  Kubernetes offers several types of persistent volumes with file support or block. Examples NFS, iSCSI, Amazon web services, Google cloud platform, and Microsoft Azure.

Whereas Docker Engine and Swarm support the mounting volumes into a container. The shared file system, including NFS, fibre channel, and iSCSI can be configured nodes. It has a Plugin option as well, which include Google Cloud Platform, NetApp,  Azure, Dell EMC, and others.

Rolling Application Upgrades and Rollback

In kubernetes, the deployment controller initiates two activities which are rolling-update and regenerate strategies. It intimates the maximum no of pods not in process or maximum number pods that are running during process time.

When it comes to Kubernetes, at rollout time, you can apply rolling updates to services. The Swarm manager helps in controlling the delay between the service deployment to various set of nodes, thereby updating a single task at a time.

Working on two systems

One should have a knowledge of Command Line Interface (CLI) to run Kubernetes on top of Docker. One should know supplemental Kubernetes common language infrastructure and  Docker Command Line Interface to take a motion within a path or structure to run those programmes.

As we know, Docker Swarm is a product of Docker, and the same language is used to navigate within the structure. This feature provides variability and speed, with this docker has got a unique edge in usability.

Load balancing

Pods are used as load balancers within the cluster and also exposed through service. Usually, an ingress is made for load balancing.

DNS component of Swarm mode helps in distributing incoming requests to a service name. Services run based on the specifications given by the client or can be assigned automatically.

Scalability

Kubernetes acts as an all in one framework for the distributed file system. It is considered as a complex system because it facilitates strong guarantee about a cluster state and a unified set of APIs, which slows down container deployment and scaling.

Whereas in Docker Swarm it can deploy containers fast compared to Kubernetes. This feature allows a fast reaction to scale on demand.

Health checks

We have two types of health checks in Kubernetes one is liveness (is app responsive), and the other is readiness (busy preparing but not yet able to serve). K8S provides a simple logging process to pull aggregate logs which creates a set of containers that generates a pod.

In  Swarm, health checks are permitted to only services. If a container is assigned with backing the service if it does not come up, (run time), a new container will replace it immediately. With the help of HEALTHCHECK instruction, a user can embed health check personality into their docker images.

High availability

All pods are distributed on among nodes in Kubernetes, and this facilitates high availability by tolerating application failure. Load balancing services identify unhealthy pods and eliminate them, and this helps or supports high availability.

Docker Swarm also provides adequately more availability, because its services are imitated in Swarm nodes. However, Swarm manager nodes take the responsibility of the complete cluster and manage the resources of worker nodes.

Networking:

Kubernetes has a flat network as it allows all pods to communicate with each other. It requires 2 CIDRs. The first one helps pods to get an IP address, and the other is for services.

Whereas in  Docker Swarm when a node joins a Cluster, it will create an overlay network for services that span all of the hosts in the Swarm. Default nodes in the Swarm cluster encrypt overly control and handle traffic between themselves. When creating an over a network, the user can encrypt container data.

Benefits of Kubernetes:

  • Kubernetes has the highest community among the container orchestration tools.
  • It is an Open Source and modular tool that can work with any tool.
  • Kubernetes is backed by the CNCF (Cloud Native Computing Foundation)
  • It has the ability to overcome Docker and Docker APIs.
  • Kubernetes autoscaling based on factors such as CPU utilization.

Drawbacks of Kubernetes:

  • Kubernetes installation is quite complex with the steep learning curve when compared to other Orchestration tools.
  • In kubernetes, we need various tools for management including Kubel CLI.
  • It is not up to par with existing Docker CLI, and other compose tools.

Benefits and Drawbacks of Docker Swarm

Benefits of Docker Swarm:

  • It is easy to and simple steps required to set up.
  • Docker Swarm is easy to deploy, and it contains Swarm mode in the docker engine.
  • It has an easier learning curve when compared to other orchestration tools.
  • Docker Swarm easily integrates with Docker CLI and Docker compose.

Drawbacks of Docker Swarm:

  • Docker Swarm has limited fault tolerance.
  • It provides limited functionality.
  • Services need to scale manually.
  • Docker has a very narrow community likewise Kubernetes.

Conclusion

Kubernetes and Docker Swarm performs unique functions and have some common and contrary features. Docker swarm easy and very simple tool to work with.  Docker swarm is suitable for those environments which require simplicity and fast development. Probably when it comes to kubernetes, it is the best fit for the environments where medium to large clusters running on complex applications.  Each Orchestration tool has its facilities and drawbacks, and we need to select one which suits us better.

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