wrapper for Vagrant ssh that manages a ControlMaster for instant ssh connections

vcssh

#!/bin/bash

# ssh to vagrant hosts can be slow due to Ruby overhead of running
# 'vagrant ssh' and ssh overhead to setup the network connection.
#
# This wrapper uses that slow setup routine once to create a reusable ssh
# ControlMaster socket. Subsequent connections invoke the ssh executable
# directly (bypassing Ruby) and connect over the ControlMaster socket
# (bypassing the connection setup) so are almost instantaneous.
#
# Example usage,
#   vcssh el6
#
# A ControlMaster is created for each user so
#   vcssh el6 -- -l joeuser
# should work as well.
#


# navigate up directory tree until .vagrant directory is found
# or we hit /.
while : ; do
  [[ "$PWD" == '/' ]] && {
    echo .vagrant directory not found
    exit 1
  }
  control_dir=$PWD/.vagrant
  [[ -d $control_dir ]] && break
  cd ..
done

vagrant_args=()
ssh_args=()
sep='-- '
args="$@"
case $args in
  (*"$sep"*)
    vagrant_args=(${args%%"$sep"*})
    ssh_args=(${args#*"$sep"})
    ;;
  (*)
    vagrant_args=($args)
    ssh_args=()
    ;;
esac

# extract any login name in the ssh args so we can
# create a distinct controlmaster channel for the user.
for i in "${!ssh_args[@]}"; do
  arg=${ssh_args[$i]}
  case $arg in
    ('-l')
      ssh_user="${ssh_args[$i+1]}"
      ;;
    ('-l'*)
      ssh_user="${arg#-l}"
      ;;
    ('reset'*)
      RM_CONTROLMASTER=1
      ;;
  esac
done

[[ -n "$ssh_user" ]] && ssh_user_prefix="${ssh_user}_"
vm_name=${vagrant_args:-default}
control_path=."vagrant/machines/${vm_name}/${ssh_user_prefix}sshcontrolmaster"

if [[ "$RM_CONTROLMASTER" -eq "1" ]]; then
  rm -rf $control_path
  echo 'controlmaster removed'
  exit
fi

#echo ssh_args ${ssh_args[@]}; echo vm_name "'$vm_name'";exit

if [[ -S "$control_path" ]]; then
  if ! echo | nc -U "$control_path" > /dev/null; then
    echo "removing stale controlmaster socket"
    rm -f "$control_path"
  fi
fi

if [[ ! -S $control_path ]]; then
  vagrant ssh-config $vm_name | ssh -t -t -fN \
    -F /dev/stdin \
    -o 'ControlPersist=4h' \
    -o 'ControlMaster auto' \
    -o "ControlPath $control_path" "$vm_name" \
    ${ssh_args[@]}
fi

ssh -o ControlPath=${control_path} ${vm_name} ${ssh_args[@]}