7342e42fce
The current behavior of `docker swarm init` is to set up a swarm that has no secret for joining, and does not require manual acceptance for workers. Since workers may sometimes receive sensitive data such as pull credentials, it makes sense to harden the defaults. This change makes `docker swarm init` generate a random secret if none is provided, and print it to the terminal. This secret will be needed to join workers or managers to the swarm. In addition to improving access control to the cluster, this setup removes an avenue for denial-of-service attacks, since the secret is necessary to even create an entry in the node list. `docker swarm init --secret ""` will set up a swarm without a secret, matching the old behavior. `docker swarm update --secret ""` removes the automatically generated secret after `docker swarm init`. Closes #23785 Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
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swarm init
Usage: docker swarm init [OPTIONS]
Initialize a Swarm.
Options:
--auto-accept value Acceptance policy (default [worker,manager])
--external-ca value Specifications of one or more certificate signing endpoints
--force-new-cluster Force create a new cluster from current state.
--help Print usage
--listen-addr value Listen address (default 0.0.0.0:2377)
--secret string Set secret value needed to accept nodes into cluster
Initialize a Swarm cluster. The docker engine targeted by this command becomes a manager in the newly created one node Swarm cluster.
$ docker swarm init --listen-addr 192.168.99.121:2377
No --secret provided. Generated random secret:
4ao565v9jsuogtq5t8s379ulb
Swarm initialized: current node (1ujecd0j9n3ro9i6628smdmth) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --secret 4ao565v9jsuogtq5t8s379ulb \
--ca-hash sha256:07ce22bd1a7619f2adc0d63bd110479a170e7c4e69df05b67a1aa2705c88ef09 \
192.168.99.121:2377
$ docker node ls
ID NAME MEMBERSHIP STATUS AVAILABILITY MANAGER STATUS LEADER
1ujecd0j9n3ro9i6628smdmth * manager1 Accepted Ready Active Reachable Yes
If a secret for joining new nodes is not provided with --secret, docker swarm init will
generate a random one and print it to the terminal (as seen in the example above). To initialize
a swarm with no secret, use --secret "".
--auto-accept value
This flag controls node acceptance into the cluster. By default, worker nodes are
automatically accepted by the cluster. This can be changed by specifying what kinds of nodes
can be auto-accepted into the cluster. If auto-accept is not turned on, then
node accept can be used to explicitly accept a node into the cluster.
For example, the following initializes a cluster with auto-acceptance of workers, but not managers
$ docker swarm init --listen-addr 192.168.99.121:2377 --auto-accept worker
--external-ca value
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 value
The node listens for inbound Swarm manager traffic on this IP:PORT
--secret string
Secret value needed to accept nodes into the Swarm