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Docker Swarm overview
To use this version of Swarm, install the Docker Engine v1.12.0-rc1 or later
from the Docker releases GitHub
repository. Alternatively, install
the latest Docker for Mac or Docker for Windows Beta.
Docker Engine 1.12 includes Docker Swarm for natively managing a cluster of Docker Engines called a Swarm. Use the Docker CLI to create a Swarm, deploy application services to the Swarm, and manage the Swarm behavior.
If you’re using a Docker version prior to v1.12.0-rc1, see Docker
Swarm.
Feature highlights
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Cluster management integrated with Docker Engine: Use the Docker Engine CLI to create a Swarm of Docker Engines where you can deploy application services. You don't need additional orchestration software to create or manage a Swarm.
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Decentralized design: Instead of handling differentiation between node roles at deployment time, Swarm handles any specialization at runtime. You can deploy both kinds of nodes, managers and workers, using the Docker Engine. This means you can build an entire Swarm from a single disk image.
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Declarative service model: Swarm uses a declarative syntax to let you define the desired state of the various services in your application stack. For example, you might describe an application comprised of a web front end service with message queueing services and a database backend.
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Desired state reconciliation: Swarm constantly monitors the cluster state and reconciles any differences between the actual state your expressed desired state.
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Multi-host networking: You can specify an overlay network for your application. Swarm automatically assigns addresses to the containers on the overlay network when it initializes or updates the application.
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Service discovery: Swarm assigns each service a unique DNS name and load balances running containers. Each Swarm has an internal DNS server that can query every container in the cluster using DNS.
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Load balancing: Using Swarm, you can expose the ports for services to an external load balancer. Internally, Swarm lets you specify how to distribute service containers between nodes.
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Secure by default: Each node in the Swarm enforces TLS mutual authentication and encryption to secure communications between itself and all other nodes. You have the option to use self-signed root certificates or certificates from a custom root CA.
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Scaling: For each service, you can declare the number of instances you want to run. When you scale up or down, Swarm automatically adapts by adding or removing instances of the service to maintain the desired state.
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Rolling updates: At rollout time you can apply service updates to nodes incrementally. Swarm lets you control the delay between service deployment to different sets of nodes. If anything goes wrong, you can roll-back an instance of a service.
What's next?
- Learn Swarm key concepts.
- Get started with the Swarm tutorial.