Docker Swarm integrates seamlessly with all existing Docker tools, is easy to set up and use, and is excellent when paired with smaller infrastructures. However, after the acquisition of Docker by Mirantis, many Swarm users feel now is the time to begin planning a move to Kubernetes. Kubernetes works excellently on all operating systems and is backed by years of industry-leading expertise. It is extremely flexible and powerful, and can manage larger, more complex infrastructures. Tools to manage, scale, and maintain containerized applications are called
orchestrators. Two of the most popular orchestration tools are Kubernetes and
Docker Swarm.

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The task allocation feature will allow us to assign work to tasks based on their IP address. The dispatcher and scheduler are in charge of assigning and instructing worker nodes on how to complete a task. Now you can connect to port 8080 on any of your worker nodes to access an instance of the NGINX service.

docker Logo

Virtual machines, on the other hand, have lost favour as they have been shown to be inefficient. Docker was later introduced, and it replaced virtual machines by allowing developers to address problems quickly and efficiently. The Kubernetes Dashboard allows you to easily scale and deploy individual applications, as well as control and monitor your different clusters.

These can be applied when creating a service or later with the docker service update command. Once your nodes are ready, you can deploy a container into your swarm. Swarm mode uses the concept of “services” to describe container deployments. Each service configuration references a Docker image and a replica count to create from that image. You can get more details about a node by running docker node ls.

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Traefik is one such offering that’s particularly well-suited for use with Docker Swarm. This sets it apart from Interlock, the ingress routing component of the commercial Docker Enterprise product, which can become unreliable when its configuration is updated. At the same time, Traefik offers comprehensive observability into the functioning of the network, so operations teams are never left in the dark. A Docker Swarm is a collection of physical or virtual machines that have been configured to join together in a cluster and run the Docker application. You can still run the Docker commands you’re used to once a set of machines has been clustered together, but they’ll be handled by the machines in your cluster.

  • Swarm mode supports rolling updates where container instances are scaled incrementally.
  • Driver support has dwindled over time as vendors moved to Kubernetes.
  • In Docker Swarm, you must have at least one node installed before you can deploy a service.
  • Docker was acquired in November 2019 by Mirantis, which has caused some concern among Docker Swarm users.
  • In terms of scalability, availability and load balancing, Kubernetes has got you covered.

Docker swarm allows you to quickly move beyond simply using Docker to run containers. With swarm, you can easily set up a cluster of Docker servers capable of providing useful orchestration features. This lab will allow you to become familiar with the process of setting up a simple swarm cluster on a set of servers. You will configure a swarm master and two worker nodes, forming a working swarm cluster. Docker is a tool that automates the deployment of an application as a lightweight container, allowing it to run in a variety of environments.

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Nodes are simply physical or virtual machines that the pods are stored on. While pods may be the building block of Kubernetes, it is the concept of desired-state that makes Kubernetes invaluable. Creating a swarm lets you replicate containers across a fleet of physical machines. Swarm also lets you add multiple manager nodes to improve fault tolerance. If the active leader drops out of the cluster, another manager can take over to maintain operations. Swarm never creates individual containers like we did in the previous step of this tutorial.

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The manager node knows the status of the worker nodes in a cluster, and the worker nodes accept tasks sent from the manager node. Every worker node has an agent that reports on the state of the node’s tasks to the manager. This way, the manager node can maintain the desired state of the cluster. In this lab, you will have the opportunity to work with a simple method of creating shared volumes usable across multiple swarm nodes using the `sshfs` volume driver.

Helix Swarm Logo

Kubernetes is the end-all-be-all for container orchestration and management. If you are working on an enterprise-sized application, then Kubernetes is your best bet. It has been utilized by countless business scenarios at Google, and has proven it can handle the workload. In terms of scalability, availability and load balancing, Kubernetes has got you covered. Kubernetes greatest asset is the sheer amount of configuration that can be leveraged to suit every possible need.

The final step is to carry out the duties that the manager node has given to the worker node. Hands down, Docker Swarm is known to have the more quick and simple setup and installation process. Swarm is also easier to pick up, even with less technical knowledge. Kubernetes on the other hand is much more complex to install and has a steeper learning curve.

Minnesota Swarm Logo

Every cluster of nodes will have worker nodes and at least one manager node. The manager node doles out various tasks to the worker nodes. Think of tasks as pieces of work that are used to maintain some desired state. Just like in Kubernetes, the manager node will tell the worker nodes to always have five available nodes.

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Because of this, routers and load balancers should be able to respond quickly as new container instances appear and disappear. By deploying a container on many nodes, both container orchestration technologies provide high availability and redundancy. When a host goes down, the services can self-heal as a result. The Worker node establishes a connection with the Manager node and monitors for new tasks.

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The worker nodes receive tasks from the manager node and the manager node in a cluster is aware of the status of the worker nodes. Every worker node has an agent who reports to the manager on the status of the node’s tasks. In this approach, the cluster’s desired state may be maintained by the manager node. Containerization provides an opportunity to move and scale applications to
clouds and data centers. Containers effectively guarantee that those applications run the
same way anywhere, allowing us to quickly and easily take advantage of all
these environments.

How Does Docker Swarm Work?

Docker Engine, the layer between the OS and container images, also has a native swarm mode. Swarm mode adds docker swarm’s orchestration features into Docker Engine 1.12 and newer releases. The node is simply an instance of a container running in a managed Swarm cluster.

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This works even if the node you connect to isn’t actually hosting one of the service’s tasks. You simply interact with the swarm and it takes care of the network routing. Despite the similar name, the two orchestrators mean very different things by
the term ‘service’. In Swarm, a service provides both scheduling docker swarm icon and
networking facilities, creating containers and providing tools for routing
traffic to them. Separating the functions of networking and container orchestration has benefits for application lifecycles, too. As an application scales and evolves, inevitably its infrastructure needs will also change.