Remote SSH command execution with Vagrant machines

remote.sh

#!/bin/bash

# file with a list of serverr
SERVER_LIST='/vagrant/servers'

# ssh options
SSH_OPTIONS='-o ConnectTimeout=2'

usage() {
  echo "Usage: ${0} [-nsv] [-f FILE] COMMAND"
  echo "Executes COMMAND as a single command on every server"
  echo "-f FILE Use FILE for the list of servers. Default ${SERVER_LIST}"
  echo "-n Dry run mode, Display the COMMAND that would have been executed and exit"
  echo "-s Execute the COMMAND using sudo on the remote server"
  echo "-v Verbose mode, Display the server name before executing COMMAND"
  exit 1
}

if [[ "${UID}" -eq 0 ]]
then
  echo "Do not execute this cript as root, Use the -s option instead"
  usage
fi

# parsing the options
while getopts f:nsv OPTION
do
  case ${OPTION} in
    f) SERVER_LIST="${OPTARG}" ;;
    n) DRY_RUN='true' ;;
    s) SUDO='sudo' ;;
    v) VERBOSE='true' ;;
  esac
done

# remove the options while leaving the remaining args
shift "$(( OPTIND -1 ))"

# check params inserted
if [[ "${#}" -lt 1 ]]
then
  usage
fi

# anything that remains is to be threated as a single command
COMMAND="${@}"

# check if the file exists
if [[ ! -e "${SERVER_LIST}" ]]
then
  echo "Cannot open ${SERVER_LIST}"
  exit 1
fi

EXIT_STATUS='0'

# loop the SERVER_LIST
for SERVER in $(cat ${SERVER_LIST})
do
  # checking VERBOSE args set
  if [[ "${VERBOSE}" == 'true' ]]
  then
    echo "${SERVER}"
  fi
  # performing the ssh command here
  SSH_COMMAND="ssh ${SSH_OPTIONS} ${SERVER} ${SUDO} ${COMMAND}"

  # Is a dry-run?
  if [[ "${DRY_RUN}" = 'true' ]]
  then
    echo "DRY RUN: ${SSH_COMMAND}"
  else
    # running command
    ${SSH_COMMAND}
    SSH_EXIT_STATUS="${?}"
    # check execution succeded
    if [[ "${SSH_EXIT_STATUS}" -ne 0 ]]
    then
      EXIT_STATUS="${SSH_EXIT_STATUS}"
      echo "Execution on ${SERVER} failed"
    fi
  fi
done

exit ${EXIT_STATUS}

servers

admin02
admin03

Vagrantfile

Vagrant.configure("2") do |config|

  config.vm.box = "jasonc/centos7"

  # first machine
  config.vm.define "admin01" do |admin01|
    admin01.vm.hostname = 'admin01'
    admin01.vm.network "private_network", ip: "10.9.8.10"
  end
  # second machine
  config.vm.define "admin02" do |admin02|
    admin02.vm.hostname = 'admin02'
    admin02.vm.network "private_network", ip: "10.9.8.11"
  end
  # third machine
  config.vm.define "admin03" do |admin03|
    admin03.vm.hostname = 'admin03'
    admin03.vm.network "private_network", ip: "10.9.8.12"
  end

end

There's some additional configuration you will have to do in order to make this script work well.

1. You will need to place the private network IPs file and the hostname inside the /etc/hosts
2. Make sure that every single machine can be reachable by using the ping command
3. Generate an ssh key with the ssh-keygen command, and then copy the public key to each VM with ssh-copy-id
4. Access a machine with ssh [admin01], find the /vagrant directory and run the remote.sh
5. Check the usage function for instructions.