docker swarm join

Estimated reading time: 4 minutes

Description

Join a swarm as a node and/or manager

Usage

docker swarm join [OPTIONS] HOST:PORT

Options

Name, shorthand Default Description
--advertise-addr   Advertised address (format: <ip|interface>[:port])
--availability active Availability of the node (“active”|“pause”|“drain”)
--data-path-addr   Address or interface to use for data path traffic (format: <ip|interface>)
--listen-addr 0.0.0.0:2377 Listen address (format: <ip|interface>[:port])
--token   Token for entry into the swarm

Parent command

Command Description
docker swarm Manage Swarm
Command Description
docker swarm ca Manage root CA
docker swarm init Initialize a swarm
docker swarm join Join a swarm as a node and/or manager
docker swarm join-token Manage join tokens
docker swarm leave Leave the swarm
docker swarm unlock Unlock swarm
docker swarm unlock-key Manage the unlock key
docker swarm update Update the swarm

Extended description

Join a node to a swarm. The node joins as a manager node or worker node based upon the token you pass with the --token flag. If you pass a manager token, the node joins as a manager. If you pass a worker token, the node joins as a worker.

Examples

Join a node to swarm as a manager

The example below demonstrates joining a manager node using a manager token.

$ docker swarm join --token SWMTKN-1-3pu6hszjas19xyp7ghgosyx9k8atbfcr8p2is99znpy26u2lkl-7p73s1dx5in4tatdymyhg9hu2 192.168.99.121:2377
This node joined a swarm as a manager.
$ docker node ls
ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
dkp8vy1dq1kxleu9g4u78tlag *  manager2  Ready   Active        Reachable
dvfxp4zseq4s0rih1selh0d20    manager1  Ready   Active        Leader

A cluster should only have 3-7 managers at most, because a majority of managers must be available for the cluster to function. Nodes that aren’t meant to participate in this management quorum should join as workers instead. Managers should be stable hosts that have static IP addresses.

Join a node to swarm as a worker

The example below demonstrates joining a worker node using a worker token.

$ docker swarm join --token SWMTKN-1-3pu6hszjas19xyp7ghgosyx9k8atbfcr8p2is99znpy26u2lkl-1awxwuwd3z9j1z3puu7rcgdbx 192.168.99.121:2377
This node joined a swarm as a worker.
$ docker node ls
ID                           HOSTNAME  STATUS  AVAILABILITY  MANAGER STATUS
7ln70fl22uw2dvjn2ft53m3q5    worker2   Ready   Active
dkp8vy1dq1kxleu9g4u78tlag    worker1   Ready   Active        Reachable
dvfxp4zseq4s0rih1selh0d20 *  manager1  Ready   Active        Leader

--listen-addr value

If the node is a manager, it will listen for inbound swarm manager traffic on this address. The default is to listen on 0.0.0.0:2377. It is also possible to specify a network interface to listen on that interface’s address; for example --listen-addr eth0:2377.

Specifying a port is optional. If the value is a bare IP address, or interface name, the default port 2377 will be used.

This flag is generally not necessary when joining an existing swarm.

--advertise-addr value

This flag specifies the address that will be advertised to other members of the swarm for API access. If unspecified, Docker will check if the system has a single IP address, and use that IP address with the listening port (see --listen-addr). If the system has multiple IP addresses, --advertise-addr must be specified so that the correct address is chosen for inter-manager communication and overlay networking.

It is also possible to specify a network interface to advertise that interface’s address; for example --advertise-addr eth0:2377.

Specifying a port is optional. If the value is a bare IP address, or interface name, the default port 2377 will be used.

This flag is generally not necessary when joining an existing swarm.

--data-path-addr

This flag specifies the address that global scope network drivers will publish towards other nodes in order to reach the containers running on this node. Using this parameter it is then possible to separate the container’s data traffic from the management traffic of the cluster. If unspecified, Docker will use the same IP address or interface that is used for the advertise address.

--token string

Secret value required for nodes to join the swarm

--availability

This flag specifies the availability of the node at the time the node joins a master. Possible availability values are active, pause, or drain.

This flag is useful in certain situations. For example, a cluster may want to have dedicated manager nodes that are not served as worker nodes. This could be achieved by passing --availability=drain to docker swarm join.