docker swarm init
Estimated reading time: 7 minutesDescription
Initialize a swarm
API 1.24+
The client and daemon API must both be at least
1.24
to use this command. Use the docker version
command on the client to check
your client and daemon API versions.
Swarm This command works with the Swarm orchestrator.
Usage
docker swarm init [OPTIONS]
Options
Name, shorthand | Default | Description |
--advertise-addr |
Advertised address (format: <ip|interface>[:port]) | |
--autolock |
Enable manager autolocking (requiring an unlock key to start a stopped manager) | |
--availability |
active |
Availability of the node (“active”|”pause”|”drain”) |
--cert-expiry |
2160h0m0s |
Validity period for node certificates (ns|us|ms|s|m|h) |
--data-path-addr |
API 1.31+ Address or interface to use for data path traffic (format: <ip|interface>) |
|
--default-addr-pool |
API 1.39+ default address pool in CIDR format |
|
--default-addr-pool-mask-length |
24 |
API 1.39+ default address pool subnet mask length |
--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 |
Force create a new cluster from current state | |
--listen-addr |
0.0.0.0:2377 |
Listen address (format: <ip|interface>[:port]) |
--max-snapshots |
API 1.25+ Number of additional Raft snapshots to retain |
|
--snapshot-interval |
10000 |
API 1.25+ 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 ca | Display and rotate the 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
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.
--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.
--default-addr-pool
This flag specifies default subnet pools for global scope networks.
Format example is --default-addr-pool 30.30.0.0/16 --default-addr-pool 40.40.0.0/16
--default-addr-pool-mask-length
This flag specifies default subnet pools mask length for default-addr-pool.
Format example is --default-addr-pool-mask-length 24
--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.
--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 init
.