docker swarm init

Description

Initialize a swarm

Usage

docker swarm init [OPTIONS]

Options

Name, shorthand	Default	Description
--advertise-addr		Advertised address (format: <ip|interface>[:port])
--autolock	false	Enable manager autolocking (requiring an unlock key to start a stopped manager)
--cert-expiry	2160h0m0s	Validity period for node certificates (ns|us|ms|s|m|h)
--dispatcher-heartbeat	5s	Dispatcher heartbeat period (ns|us|ms|s|m|h)
--external-ca		Specifications of one or more certificate signing endpoints
--force-new-cluster	false	Force create a new cluster from current state
--listen-addr	0.0.0.0:2377	Listen address (format: <ip|interface>[:port])
--max-snapshots	0	Number of additional Raft snapshots to retain
--snapshot-interval	10000	Number of log entries between Raft snapshots
--task-history-limit	5	Task history retention limit

Parent command

Command	Description
docker swarm	Manage Swarm

Related commands

Command	Description
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

Initialize a swarm. The docker engine targeted by this command becomes a manager in the newly created single-node swarm.

Examples

$ docker swarm init --advertise-addr 192.168.99.121
Swarm initialized: current node (bvz81updecsj6wjz393c09vti) is now a manager.

To add a worker to this swarm, run the following command:

    docker swarm join \
    --token SWMTKN-1-3pu6hszjas19xyp7ghgosyx9k8atbfcr8p2is99znpy26u2lkl-1awxwuwd3z9j1z3puu7rcgdbx \
    172.17.0.2:2377

To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.

docker swarm init generates two random tokens, a worker token and a manager token. When you join a new node to the swarm, the node joins as a worker or manager node based upon the token you pass to swarm join.

After you create the swarm, you can display or rotate the token using swarm join-token.

--autolock

This flag enables automatic locking of managers with an encryption key. The private keys and data stored by all managers will be protected by the encryption key printed in the output, and will not be accessible without it. Thus, it is very important to store this key in order to activate a manager after it restarts. The key can be passed to docker swarm unlock to reactivate the manager. Autolock can be disabled by running docker swarm update --autolock=false. After disabling it, the encryption key is no longer required to start the manager, and it will start up on its own without user intervention.

--cert-expiry

This flag sets the validity period for node certificates.

--dispatcher-heartbeat

This flag sets the frequency with which nodes are told to use as a period to report their health.

--external-ca

This flag sets up the swarm to use an external CA to issue node certificates. The value takes the form protocol=X,url=Y. The value for protocol specifies what protocol should be used to send signing requests to the external CA. Currently, the only supported value is cfssl. The URL specifies the endpoint where signing requests should be submitted.

--force-new-cluster

This flag forces an existing node that was part of a quorum that was lost to restart as a single node Manager without losing its data.

--listen-addr

The node listens 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.

--advertise-addr

This flag specifies the address that will be advertised to other members of the swarm for API access and overlay networking. 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.

--task-history-limit

This flag sets up task history retention limit.

--max-snapshots

This flag sets the number of old Raft snapshots to retain in addition to the current Raft snapshots. By default, no old snapshots are retained. This option may be used for debugging, or to store old snapshots of the swarm state for disaster recovery purposes.

--snapshot-interval

This flag specifies how many log entries to allow in between Raft snapshots. Setting this to a higher number will trigger snapshots less frequently. Snapshots compact the Raft log and allow for more efficient transfer of the state to new managers. However, there is a performance cost to taking snapshots frequently.