Support for executing one off commands on nodes

[g0t4]

Consul has a convenient subcommand to execute a command on all nodes or a subset of nodes:
consul exec -node worker uptime. This command is propagated via gossip so there's no guarantee of execution. Nonetheless, this is great for one off troubleshooting and when learning, to execute commands across nodes.

See more details here: https://www.consul.io/docs/commands/exec.html

Perhaps we could have something like:

swarmctl node exec -f name=worker -c uptime
swarmctl node exec -f name=worker -c "docker image ls"

docker node exec -f name=worker -c uptime
docker node exec -f name=worker -c "docker image ls"

Think of this as syntactic sugar over using docker node ls -f worker and then ssh -c. Though, with docker node exec I wouldn't need to have direct SSH access to nodes.

[aluzzardi]

Thanks for the suggestion @g0t4.

It's an interesting idea, however, we are not looking to implement it in the near future.

Something similar could be achieved with https://github.com/crosbymichael/slex and some bash around the docker CLI

/cc @crosbymichael