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Docker Swarm Clusters Overview

Docker Swarm is a container orchestration tool that allows you to manage and scale a cluster of Docker hosts. While standalone Docker is great for running containers on a single host, Docker Swarm extends this capability to a group of machines, forming a swarm that can efficiently distribute and manage containerized applications.

Why Docker Swarm?​

If you've used regular Docker deployments with Appliku, you already know the flexibility containerization provides. Docker Swarm is the next step in scaling your applications beyond the capacity of a single server.

Docker Swarm allows you to:

  • Scale horizontally — run many copies of your application
  • Scale server resources — add, remove, or replace servers as workload changes
  • Go multi-cloud — have servers across multiple cloud providers or regions, avoiding vendor lock-in
  • Simplify placement — add more apps to the cluster without worrying about container placement across servers
  • Optimize costs — run on cloud providers that offer the best price for servers

How Docker Swarm Works​

Docker Swarm works by turning a group of Docker hosts into a single virtual host, allowing you to manage and orchestrate containers across multiple machines.

  • Appliku initializes Docker Swarm on the first server in your cluster, making it a Swarm Manager
  • Other machines that you add to the swarm join as worker nodes
  • An Nginx load balancer is deployed on the first server to distribute traffic between all containers across all worker nodes
  • Docker Swarm overlay network handles distributing traffic and removing broken nodes from load balancing
  • If a worker node fails, the Swarm Manager reschedules tasks on other healthy nodes, maintaining the desired state

Every application you deploy to a Managed Docker Swarm Cluster is a separate stack. Each process in your application becomes a service in the stack.

Scaling Applications​

You can easily manage the number of containers/replicas running for each process in your app. Scale every process of every app individually at any time.

Compared to standalone Docker, Docker Swarm allows scaling a process even in a cluster with only one server, fully utilizing its resources.

Multi-Cloud Support​

You can add servers from different providers to a given cluster. This allows you to:

  • Optimize costs across providers
  • Put servers closer to your customers
  • Increase stability and availability

Application Logs​

You can access logs of every application in the dashboard by going from the Application Overview page to App Logs and selecting what process/service you want to fetch logs for.

Next Steps​