Kubernetes v/s Docker Swarm

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Basically, both Kubernetes and Docker Swarm both are the container orchestration tool. The rise in interest to containers has in turn brought in higher demands for their deployment and management. Both Kubernetes and Docker Swarm are important tools that are used to deploy containers inside a cluster. So the question arises here is which one to use?

So lets discuss one by one and see the the differances between them.

Introduction to Kubernetes:

The name Kubernetes originates from Greek, meaning helmsman or pilot. Kubernetes is an open-source, portable, and extensible platform for managing containerized workload and services. That facilitates both declarative configuration and automation. Kubernetes manage the containers that run the applications and ensure that there is no downtime into a huge scale production environment.

Introduction to Docker swarm:

Docker swarm is a container orchestration tool, meaning that it allows the user to manage multiple containers deployed across multiple host machines. Docker Swarm is designed to work around four key principles:

  1. Less cluttered/heavy and with just working methodology
  2. No Single Point of Failure option for Docker Swarm
  3. Secure due to auto-generation of security certificates.
  4. Compatibility with Backward versions easily.

Here you get to know that both in some manner are the same , So now let’s check out the differences and see:

Installation and Setup:

The installation setup is complex of Kubernetes . It needs serious planning. The instruction of setup change as per the os. You need to choose the correct IP ranges. Various 3rd party packages like minikube/microk8s and kubectl/kubeadm are need to be install for the working and development of kubernetes.

Where as the Docker-Swarm setup is very simple as compared to kubernetes. Only one set of tools is required to learn to build upon environment and configuration. Docker Swarm also provides flexibility by allowing any new node to join an existing cluster as either a manager or a worker.

Service Discovery and Load balancing:

Where as in “Docker-Swarm” has inbuilt feature of load balancing. All containers within a single cluster join a common network that allows connections from any node to any container. I means it support automatic load balancing.

Automated rollouts and rollbacks:

Kubernetes supports the automated rollout and rollbacks which means you can define the desired state for your containers and it fails to achieve that desired state it rolls back to the previous deployment.

Whreas in docker swarm  at rollout time you can apply service updates to nodes incrementally. The swarm manager lets you control the delay between service deployment to different sets of nodes. If anything goes wrong, you can roll back to a previous version of the service.

Data volumes:

Volumes in the kubernetes are abstraction to share the data between the differant containers in the same pod. In kubernetes volumes have particuar lifetime. It support both persistant and non-persistent volume. You can create both local as well as global volumes.

Whereas in “Docker-Swarm” we can create only local volumes. These volumes are directories shared within one or more containers. Data volumes also persist even when we delete the volumes that container uses.  To create global volumes, the Docker engine supports volume plugins.

Networking:

Kubernetes commonly uses flannel to accomplish container networking. Containers are joining in a virtual network and announce through etcd. TLS authentication is also possible but requires certificates to generate and need to install manually to all nodes.

Docker Swarm forms a multi-host ingress network overlay that connects containers running on all cluster nodes. More inter-container networks can be configured manually. Connections between nodes are also automatically secured through TLS authentication with certificates.

Logging and monitoring:

Kubernetes supports multiple versions of logging and monitoring when we deploy service within the cluster:

  • ELK Stack — ElasticSearch, Logstash, Kibana.
  • Heapster/Grafana/ Influx for monitoring in the container

Docker Swarm support for only monitoring with third-party applications.

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