github.com/portworx/docker@v1.12.1/docs/swarm/index.md (about) 1 <!--[metadata]> 2 +++ 3 title = "Swarm mode overview" 4 description = "Docker Engine swarm mode overview" 5 keywords = ["docker, container, cluster, swarm"] 6 [menu.main] 7 identifier="swarm_overview" 8 parent="engine_swarm" 9 weight="1" 10 +++ 11 <![end-metadata]--> 12 # Swarm mode overview 13 14 To use Docker Engine in swarm mode, install the Docker Engine `v1.12.0` or 15 later from the [Docker releases GitHub 16 repository](https://github.com/docker/docker/releases). Alternatively, install 17 the latest Docker for Mac or Docker for Windows Beta. 18 19 Docker Engine 1.12 includes swarm mode for natively managing a cluster of 20 Docker Engines called a *swarm*. Use the Docker CLI to create a swarm, deploy 21 application services to a swarm, and manage swarm behavior. 22 23 24 If you’re using a Docker version prior to `v1.12.0`, see [Docker 25 Swarm](https://docs.docker.com/swarm). 26 27 ## Feature highlights 28 29 * **Cluster management integrated with Docker Engine:** Use the Docker Engine 30 CLI to create a swarm of Docker Engines where you can deploy application 31 services. You don't need additional orchestration software to create or manage 32 a swarm. 33 34 * **Decentralized design:** Instead of handling differentiation between node 35 roles at deployment time, the Docker Engine handles any specialization at 36 runtime. You can deploy both kinds of nodes, managers and workers, using the 37 Docker Engine. This means you can build an entire Swarm from a single disk 38 image. 39 40 * **Declarative service model:** Docker Engine uses a declarative approach to 41 let you define the desired state of the various services in your application 42 stack. For example, you might describe an application comprised of a web front 43 end service with message queueing services and a database backend. 44 45 * **Scaling:** For each service, you can declare the number of tasks you want to 46 run. When you scale up or down, the swarm manager automatically adapts by 47 adding or removing tasks to maintain the desired state. 48 49 * **Desired state reconciliation:** The swarm manager node constantly monitors 50 the cluster state and reconciles any differences between the actual state your 51 expressed desired state. For example, if you set up a service to run 10 52 replicas of a container, and a worker machine hosting two of those replicas 53 crashes, the manager will create two new replicas to replace the ones that 54 crashed. The swarm manager assigns the new replicas to workers that are 55 running and available. 56 57 * **Multi-host networking:** You can specify an overlay network for your 58 services. The swarm manager automatically assigns addresses to the containers 59 on the overlay network when it initializes or updates the application. 60 61 * **Service discovery:** Swarm manager nodes assign each service in the swarm a 62 unique DNS name and load balances running containers. You can query every 63 container running in the swarm through a DNS server embedded in the swarm. 64 65 * **Load balancing:** You can expose the ports for services to an 66 external load balancer. Internally, the swarm lets you specify how to distribute 67 service containers between nodes. 68 69 * **Secure by default:** Each node in the swarm enforces TLS mutual 70 authentication and encryption to secure communications between itself and all 71 other nodes. You have the option to use self-signed root certificates or 72 certificates from a custom root CA. 73 74 * **Rolling updates:** At rollout time you can apply service updates to nodes 75 incrementally. The swarm manager lets you control the delay between service 76 deployment to different sets of nodes. If anything goes wrong, you can 77 roll-back a task to a previous version of the service. 78 79 ## What's next? 80 * Learn swarm mode [key concepts](key-concepts.md). 81 * Get started with the [swarm mode tutorial](swarm-tutorial/index.md). 82 * Explore swarm mode CLI commands: 83 * [swarm init](../reference/commandline/swarm_init.md) 84 * [swarm join](../reference/commandline/swarm_join.md) 85 * [service create](../reference/commandline/service_create.md) 86 * [service inspect](../reference/commandline/service_inspect.md) 87 * [service ls](../reference/commandline/service_ls.md) 88 * [service rm](../reference/commandline/service_rm.md) 89 * [service scale](../reference/commandline/service_scale.md) 90 * [service ps](../reference/commandline/service_ps.md) 91 * [service update](../reference/commandline/service_update.md)