github.com/portworx/docker@v1.12.1/docs/swarm/index.md (about)

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     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"
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    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)