Information
By default, Docker swarm services will listen on all interfaces on the host. This may not be necessary for the operation of the swarm where the host has multiple network interfaces.
Rationale:
When a swarm is initialized the default value for the --listen-addr flag is 0.0.0.0:2377 which means that swarm services will listen on all interfaces on the host. If a host has multiple network interfaces this may be undesirable as it could expose swarm services to networks which are not involved with the operation of the swarm.
By passing a specific IP address to the --listen-addr, a specific network interface can be specified, limiting this exposure.
Impact:
None
Solution
Resolving this issues requires re-initialization of the swarm, specifying a specific interface for the --listen-addr parameter.
Default Value:
By default, Docker swarm services listen on all available host interfaces.