manage — Create a Swarm manager

Estimated reading time: 10 minutes

Prerequisite: Before using manage to create a Swarm manager, establish a discovery backend as described in this discovery topic.

The manage command creates a Swarm manager whose purpose is to receive commands on behalf of the cluster and assign containers to Swarm nodes. You can create multiple Swarm managers as part of a high-availability cluster.

To create a Swarm manager, use the following syntax:

$ docker run swarm manage [OPTIONS] <discovery>

For example, you can use manage to create a Swarm manager in a high-availability cluster with other managers:

$ docker run -d -p 4000:4000 swarm manage -H :4000 --replication --advertise 172.30.0.161:4000 consul://172.30.0.165:8500

Or, for example, you can use it to create a Swarm manager that uses Transport Layer Security (TLS) to authenticate the Docker Client and Swarm nodes:

$ docker run -d -p 3376:3376 -v /home/ubuntu/.certs:/certs:ro swarm manage --tlsverify --tlscacert=/certs/ca.pem --tlscert=/certs/cert.pem --tlskey=/certs/key.pem --host=0.0.0.0:3376 token://$TOKEN

Argument

The manage command has only one argument:

<discovery> — Discovery backend

Before you create a Swarm manager, create a discovery token or set up a discovery backend for your cluster.

When you create the swarm node, use the <discovery> argument to specify one of the following discovery backends:

  • token://<token>
  • consul://<ip1>/<path>
  • etcd://<ip1>,<ip2>,<ip3>/<path>
  • file://<path/to/file>
  • zk://<ip1>,<ip2>/<path>
  • [nodes://]<iprange>,<iprange>

Where:

  • <token> is a discovery token generated by Docker Hub’s hosted discovery service. To generate this discovery token, use the create command. > Warning: Docker Hub’s hosted discovery backend is not recommended for production use. It’s intended only for testing/development.

  • ip1, ip2, ip3 are each the IP address and port numbers of a discovery backend node.
  • path (optional) is a path to a key-value store on the discovery backend. When you use a single backend to service multiple clusters, you use paths to maintain separate key-value stores for each cluster.
  • path/to/file is the path to a file that contains a static list of the Swarm managers and nodes that are members the cluster.
  • iprange is an IP address or a range of IP addresses followed by a port number.

Here are a pair of <discovery> argument examples:

  • A discovery token: token://0ac50ef75c9739f5bfeeaf00503d4e6e
  • A Consul node: consul://172.30.0.165:8500

The environment variable for <discovery> is $SWARM_DISCOVERY.

For more information and examples, see the Docker Swarm Discovery topic.

Options

The manage command has the following options:

--strategy — Scheduler placement strategy

Use --strategy "<value>" to tell the Docker Swarm scheduler which placement strategy to use.

Where <value> is:

  • spread — Assign each container to the Swarm node with the most available resources.
  • binpack - Assign containers to one Swarm node until it is full before assigning them to another one.
  • random - Assign each container to a random Swarm node.

By default, the scheduler applies the spread strategy.

For more information and examples, see Docker Swarm strategies.

--filter, -f — Scheduler filter

Use --filter <value> or -f <value> to tell the Docker Swarm scheduler which nodes to use when creating and running a container.

Where <value> is:

  • health — Use nodes that are running and communicating with the discovery backend.
  • port — For containers that have a static port mapping, use nodes whose corresponding port number is available (i.e., not occupied by another container or process).
  • dependency — For containers that have a declared dependency, use nodes that already have a container with the same dependency.
  • affinity — For containers that have a declared affinity, use nodes that already have a container with the same affinity.
  • constraint — For containers that have a declared constraint, use nodes that already have a container with the same constraint.

You can use multiple scheduler filters, like this:

--filter <value> --filter <value>

For more information and examples, see Swarm filters.

--host, -H — Listen to IP/port

Use --host <ip>:<port> or -H <ip>:<port> to specify the IP address and port number to which the manager listens for incoming messages. If you replace <ip> with zeros or omit it altogether, the manager uses the default host IP. For example, --host=0.0.0.0:3376 or -H :4000.

The environment variable for --host is $SWARM_HOST.

--replication — Enable Swarm manager replication

Enable Swarm manager replication between the primary and secondary managers in a high-availability cluster. Replication mirrors cluster information from the primary to the secondary managers so that, if the primary manager fails, a secondary can become the primary manager.

--replication-ttl — Leader lock release time on failure

Use --replication-ttl "<delay>s" to specify the delay, in seconds, before notifying secondary managers that the primary manager is down or unreachable. This notification triggers an election in which one of the secondary managers becomes the primary manager. By default, the delay is 15 seconds.

Use --advertise <ip>:<port> or --addr <ip>:<port> to advertise the IP address and port number of the Docker Engine. For example, --advertise 172.30.0.161:4000. Other Swarm managers MUST be able to reach this Swarm manager at this address.

The environment variable for --advertise is $SWARM_ADVERTISE.

--tls — Enable transport layer security (TLS)

Use --tls to enable transport layer security (TLS). If you use --tlsverify, you do not need to use --tls.

--tlscacert — Path to a CA’s public key file

Use --tlscacert=<path/file> to specify the path and filename of the public key (certificate) from a Certificate Authority (CA). For example, --tlscacert=/certs/ca.pem. When specified, the manager trusts only remotes that provide a certificate signed by the same CA.

--tlscert — Path to the node’s TLS certificate file

Use --tlscert to specify the path and filename of the manager’s certificate (signed by the CA). For example, --tlscert=/certs/cert.pem.

--tlskey — Path to the node’s TLS key file

Use --tlskey to specify the path and filename of the manager’s private key (signed by the CA). For example, --tlskey=/certs/key.pem.

--tlsverify — Use TLS and verify the remote

Use --tlsverify to enable transport layer security (TLS) and accept connections from only those managers, nodes, and clients that have a certificate signed by the same CA. If you use --tlsverify, you do not need to use --tls.

--engine-refresh-min-interval — Set engine refresh minimum interval

Use --engine-refresh-min-interval "<interval>s" to specify the minimum interval, in seconds, between Engine refreshes. By default, the interval is 30 seconds.

When the primary manager in performs an Engine refresh, it gets updated information about an Engine in the cluster. The manager uses this information to, among other things, determine whether the Engine is healthy. If there is a connection failure, the manager determines that the node is unhealthy. The manager retries an Engine refresh a specified number of times. If the Engine responds to one of the retries, the manager determines that the Engine is healthy again. Otherwise, the manager stops retrying and ignores the Engine.

--engine-refresh-max-interval — Set engine refresh maximum interval

Use --engine-refresh-max-interval "<interval>s" to specify the minimum interval, in seconds, between Engine refresh. By default, the interval is 60 seconds.

--engine-failure-retry — Set engine failure retry count

Use --engine-failure-retry "<number>" to specify the number of retries to attempt if the engine fails. By default, the number is 3 retries.

--engine-refresh-retry — Deprecated

Deprecated; Use --engine-failure-retry instead of --engine-refresh-retry "<number>". The default number is 3 retries.

--heartbeat — Period between each heartbeat

Use --heartbeat "<interval>s" to specify the interval, in seconds, between heartbeats the manager sends to the primary manager. These heartbeats indicate that the manager is healthy and reachable. By default, the interval is 60 seconds.

--api-enable-cors, --cors — Enable CORS headers in the Engine API

Use --api-enable-cors or --cors to enable cross-origin resource sharing (CORS) headers in the Engine API.

--cluster-driver, -c — Cluster driver to use

Use --cluster-driver "<driver>", -c "<driver>" to specify a cluster driver to use. Where <driver> is one of the following:

  • swarm is the Docker Swarm driver.
  • mesos-experimental is the Mesos cluster driver.

By default, the driver is swarm.

For more information about using Mesos driver, see Using Docker Swarm and Mesos.

--cluster-opt — Cluster driver options

You can enter multiple cluster driver options, like this:

--cluster-opt <value> --cluster-opt <value>

Where <value> is one of the following:

  • swarm.overcommit=0.05 — Set the fractional percentage by which to overcommit resources. The default value is 0.05, or 5 percent.
  • swarm.createretry=0 — Specify the number of retries to attempt when creating a container fails. The default value is 0 retries.
  • mesos.address= — Specify the Mesos address to bind on. The environment variable for this option is $SWARM_MESOS_ADDRESS.
  • mesos.checkpointfailover=false — Enable Mesos checkpointing, which allows a restarted slave to reconnect with old executors and recover status updates, at the cost of disk I/O. The environment variable for this option is $SWARM_MESOS_CHECKPOINT_FAILOVER. The default value is false (disabled).
  • mesos.port= — Specify the Mesos port to bind on. The environment variable for this option is $SWARM_MESOS_PORT.
  • mesos.offertimeout=30s — Specify the Mesos timeout for offers, in seconds. The environment variable for this option is $SWARM_MESOS_OFFER_TIMEOUT. The default value is 30s.
  • mesos.offerrefusetimeout=5s — Specify timeout for Mesos to consider unused resources refused, in seconds. The environment variable for this option is $SWARM_MESOS_OFFER_REFUSE_TIMEOUT. The default value is 5s.
  • mesos.tasktimeout=5s — Specify the timeout for Mesos task creation, in seconds. The environment variable for this option is $SWARM_MESOS_TASK_TIMEOUT. The default value is 5s.
  • mesos.user= — Specify the Mesos framework user name. The environment variable for this option is $SWARM_MESOS_USER.

--discovery-opt — Discovery options

Use --discovery-opt <value> to discovery options, such as paths to the TLS files; the CA’s public key certificate, the certificate, and the private key of the distributed K/V store on a Consul or etcd discovery backend. You can enter multiple discovery options. For example:

--discovery-opt kv.cacertfile=/path/to/mycacert.pem \
--discovery-opt kv.certfile=/path/to/mycert.pem \
--discovery-opt kv.keyfile=/path/to/mykey.pem \

For more information, see Use TLS with distributed key/value discovery

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