Container orchestration is fast evolving and Kubernetes and Docker Swarm are the two major players in this field. Both Kubernetes and Docker Swarm are important tools that are used to deploy containers inside a cluster. Kubernetes and Docker Swarm have carved respectable niches for themselves, cementing their places in the Docker ecosystem. Let's briefly look into Kubernetes and Docker Swarm before moving onto see the differences between these two containerization platforms.
Overview of Kubernetes
Kubernetes (also known as K8s) is based on years of Google's experience of running workloads at a huge scale in production. According to the Kubernetes website, “Kubernetes is an open-source system for automating deployment, scaling, and management of containerized applications.” In other words, Kubernetes is a powerful system used in the management of containerized applications in a clustered environment.
Overview of Docker Swarm
Docker Swarm is the clustering container orchestration tool of Docker. It uses the standard Docker API and networking, making it easy to drop into an environment where you're already working with the Docker containers. Dock Swarm is designed to work around four key principles:
- Simple yet powerful with a “just works” user experience
- Resilient zero single-point-of-failure architecture
- Secure by default with automatically generated certificates
- Backward compatibility with existing components
Kubernetes vs Docker Swarm
Although both orchestration tools offer much of the same functionalities, there are fundamental differences between how the two operate. Below listed are some of the most notable points:
- Application definition
In Kubernetes, an application can be deployed using a combination of pods, deployments, and services (or micro-services).
Whereas, in Docker Swarm, applications can be deployed as services (or micro-services) in a Swarm cluster. YAML files can be used to specify multi-container. Moreover, Docker Compose can deploy the app.
- Installation and set-up
In Kubernetes, installation is manual and it takes serious planning to make Kubernetes up and running. Installation instructions differ from OS to OS and provider to provider. Furthermore, in K8s, you need to know the cluster configuration such as IP addresses of a node or which node takes what role in advance.
Compared to Kubernetes, Docker Swarm is simple to install. With Docker, only one set of tools are required to learn to build upon the 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.
- Working on two systems
You need to know CLI (Command Line Interface) to run Kubernetes on top of Docker. Knowing Docker CLI helps you navigate within a structure and then supplemental Kubernetes common language infrastructure to run for those programs.
Since Docker Swarm is a tool of Docker, a common language is used to navigate within a structure. This provides variability and speed to this tool and gives Docker a significant usability edge.
- Logging and monitoring
Kubernetes supports multiple versions of logging and monitoring when the services are deployed within the cluster:
- Elasticsearch/Kibana (ELK) logs within the container
- Heapster/Grafana/ Influx for monitoring in the container
- Sysdig cloud integration
Docker Swarm supports monitoring only with third-party applications. It is recommended to use Docker with Reimann for monitoring, however since Docker Swarm has an open API, it makes it easier to connect with plenty of apps.
Kubernetes is more of an all-in-one framework for distributed systems. It is a complex system as it offers a unified set of APIs and strong guarantees about the cluster state, which slows down container deployment and scaling.
Compared to Kubernetes, Docker Swarm can deploy containers faster; this allows fast reaction times to scale on demand.
- High availability
In Kubernetes, all pods are distributed among nodes and this provides high availability by tolerating application failure. In Kubernetes, load-balancing services detect unhealthy pods and remove them, this supports high availability.
Docker Swarm also provides high availability as services can be replicated in Swarm nodes. In Docker Swarm, Swarm manager nodes are responsible for the whole cluster and manage the resources of worker nodes.
Kubernetes network is flat, as it enables all pods to communicate with one another. In Kubernetes, the model requires two CIDRs. The first one requires pods to get an IP address, the other is for services.
In a Docker Swarm, a node joining a cluster creates an overlay network of services that span all of the hosts in the Swarm and a host-only Docker bridge network for containers. In Docker Swarm, users have the option to encrypt container data traffic when creating an overlay network on their own.
Benefits & drawbacks of Kubernetes
Benefits of Kubernetes:
- Kubernetes is backed by the Cloud Native Computing Foundation (CNCF).
- Kubernetes has a huge open source community backing it with over 100,000 commits and 3000 contributors.
- The open source and modular nature of Kubernetes enable it to work with any OS.
- Kubernetes provides easy service organization with pods Drawbacks of Kubernetes
- Kubernetes installation can be quite complex with steep learning curve, especially if you are going about it alone. An option to solve this issue is to opt for a managed Kubernetes-as-a-service such as ours.
- In Kubernetes, it is required to have a separate set of tools for management, including kubectl CLI.
- It is incompatible with existing Docker CLI and Compose tools
Benefits & drawbacks of Docker Swarm
Benefits of Docker Swarm
- Docker Swarm is easy to install with a fast setup.
- Docker Swarm is a lightweight installation. It is simpler to deploy and Swarm mode is included in the Docker engine.
- Docker Swarm has an easier learning curve.
- Docker Swarm smoothly integrates with Docker Compose and Docker CLI. That's because these are native Docker tools. Most of the Docker CLI commands will work with Swarm. Drawbacks of Docker Swarm
- Docker Swarm provides limited functionality.
- Docker Swarm has limited fault tolerance.
- Docker Swarm has a smaller community and project compared to Kubernetes community
- In Docker Swarm, services can be scaled manually.
In a Nutshell
It is not easy to compare those two containerization platforms as Docker Swarm is a simple and easy solution to work with whereas Kubernetes is targeted to those who require full fledge support with higher complexity. Docker Swarm is preferred in environments where simplicity and fast development is favored and Kubernetes is suitable for environments where medium to large clusters are running complex applications.
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