Docker command wrapper to add ability to use "docker service exec <SERVICE_NAME> <CMD>" for executing a task on a Docker service

docker.sh

#!/bin/bash

# add ability to use "docker service exec <SERVICE_NAME> <CMD>" for executing a task on a Docker service
# to use this script you need to expose Docker API over TCP on all nodes of you swarm cluster

declare -A NODE_IPS
# here list all nodes of you cluster
NODE_IPS[<NODE01_NAME>]="<NODE01_IP>"
NODE_IPS[<NODE02_NAME>]="<NODE02_IP>"
NODE_IPS[<NODE03_NAME>]="<NODE03_IP>"

lsof -ti:12375 | xargs kill -9
# here give a way to connect to one manager node
ssh <SSH_USER>@<MANAGER_NODE_IP> -fN -L 12375:localhost:12375

if [[ $1 == "service" && $2 == "exec" ]]; then
  # find a node running the task
  SERVICE_INFO=($(docker -H 127.0.0.1:12375 service ps $3 --filter "desired-state=running" --format "{{.Node}} {{.ID}}" --no-trunc | head -1))
  ID_CONTAINER=$(docker -H 127.0.0.1:12375 inspect ${SERVICE_INFO[1]} --format '{{.Status.ContainerStatus.ContainerID}}')
  NODE_IP=${NODE_IPS[${SERVICE_INFO[0]}]}
  # connect to a node running task
  lsof -ti:12376 | xargs kill -9
  ssh <SSH_USER>@$NODE_IP -fN -L 12376:localhost:12375
  docker -H 127.0.0.1:12376 exec -it $ID_CONTAINER ${@:4}
else
  docker -H 127.0.0.1:12375 "$@"
fi