automation2.sh

#!/bin/bash
# vim: set tabstop=2 smarttab shiftwidth=2 softtabstop=2 expandtab foldmethod=syntax :
#
# Small script to automate custom shell command execution
# Current version can be found here:
# https://github.com/ChrLau/scripts/blob/master/automation2.sh

VERSION="1.5"
SCRIPT="$(basename "$0")"
SSH="$(command -v ssh)"
TEE="$(command -v tee)"
# Colored output
RED="\e[31m"
GREEN="\e[32m"
ENDCOLOR="\e[0m"

# Test if ssh is present and executeable
if [ ! -x "$SSH" ]; then
  echo "${RED}This script requires ssh to connect to the servers. Exiting.${ENDCOLOR}"
  exit 2;
fi

# Test if tee is present and executeable
if [ ! -x "$TEE" ]; then
  echo "${RED}tee not found.${ENDCOLOR} ${GREEN}Script can still be used,${ENDCOLOR} ${RED}but option -w CAN NOT be used.${ENDCOLOR}"
fi

function HELP {
  echo "$SCRIPT $VERSION: Execute custom shell commands on lists of hosts"
  echo "Usage: $SCRIPT -l /path/to/host.list -c \"command\" [-u <user>] [-a <YES|NO>] [-r] [-s \"options\"] [-w \"/path/to/logfile.log\"]"
  echo ""
  echo "Parameters:"
  echo " -l   Path to the hostlist file, 1 host per line"
  echo " -c   The command to execute. Needs to be in double-quotes. Else getops interprets it as separate arguments"
  echo " -u   (Optional) The user used during SSH-Connection. (Default: \$USER)"
  echo " -a   (Optional) Abort when the ssh-command fails? Use YES or NO (Default: YES)"
  echo " -r   (Optional) When given command will be executed via 'sudo su -c'"
  echo " -s   (Optional) Any SSH parameters you want to specify Needs to be in double-quotes. (Default: empty)"
  echo "                 Example: -s \"-i /home/user/.ssh/id_user\""
  echo " -w   (Optional) Write STDERR and STDOUT to logfile (on the machine where $SCRIPT is executed)"
  echo ""
  echo "No arguments or -h will print this help."
  exit 0;
}

# Print help if no arguments are given
if [ "$#" -eq 0 ]; then
  HELP
fi

# Parse arguments
while getopts ":l:c:u:a:hrs:w:" OPTION; do
  case "$OPTION" in
    l)
      HOSTLIST="${OPTARG}"
      ;;
    c)
      COMMAND="${OPTARG}"
      ;;
    u)
      SSH_USER="${OPTARG}"
      ;;
    a)
      ABORT="${OPTARG}"
      ;;
    r)
      SUDO="YES"
      ;;
    s)
      SSH_PARAMS="${OPTARG}"
      ;;
    w)
      LOGFILE="${OPTARG}"
      ;;
    h)
      HELP
      ;;
    *)
      HELP
      ;;
# Not needed as we use : as starting char in getopts string
#    :)
#      echo "Missing argument"
#      ;;
#    \?)
#      echo "Invalid option"
#      exit 1
#      ;;
  esac
done

# Give usage message and print help if both arguments are empty
if [ -z "$HOSTLIST" ] || [ -z "$COMMAND" ]; then
  echo "You need to specify -l and -c. Exiting."
  exit 1;
fi

# Check if username was provided, if not use $USER environment variable
if [ -z "$SSH_USER" ]; then
  SSH_USER="$USER"
fi

# Check for YES or NO
if [ -z "$ABORT" ]; then
  # If empty, set to YES (default)
  ABORT="YES"
# Check if it's not NO or YES - we want to ensure a definite decision here
elif [ "$ABORT" != "NO" ] && [ "$ABORT" != "YES" ]; then
  echo  "-a accepts either YES or NO (case-sensitive)"
  exit 1
fi

# If variable logfile is not empty
if [ -n "$LOGFILE" ]; then

  # Set pipefail variable
  # As we use "ssh command | tee" and tee will always succeed our check for non-zero exit-codes doesn't work
  #
  # The exit status of a pipeline is the exit status of the last command in the pipeline,
  #  unless the pipefail option is enabled (see: The Set Builtin).
  # If pipefail is enabled, the pipeline's return status is the value of the last (rightmost)
  #  command to exit with a non-zero status, or zero if all commands exit successfully.
  set -o pipefail

  # Check if logfile is not present
  if [ ! -e "$LOGFILE" ]; then
    # Check if creating it was unsuccessful
    if ! touch "$LOGFILE"; then
      echo "${RED}Could not create logfile at $LOGFILE. Aborting. Please check permissions.${ENDCOLOR}"
      exit 1
    fi
  # When logfile is present..
  else
    # Check if it's writeable and abort when not
    if [ ! -w "$LOGFILE" ]; then
      echo "${RED}$LOGFILE is NOT writeable. Aborting. Please check permissions.${ENDCOLOR}"
      exit 1
    fi
  fi
fi

# Execute command via sudo or not?
if [ "$SUDO" = "YES" ]; then
  COMMANDPART="sudo su -c '${COMMAND}'"
else
  COMMANDPART="${COMMAND}"
fi

# Check if hostlist is readable
if [ -r "$HOSTLIST" ]; then
  # Check that hostlist is not 0 bytes
  if [ -s "$HOSTLIST" ]; then
  
    while IFS= read -r HOST
    do

      getent hosts "$HOST" &> /dev/null
      
      # getent returns exit code of 2 if a hostname isn't resolving
      # shellcheck disable=SC2181
      if [ "$?" -ne 0 ]; then
        echo -e "${RED}Host: $HOST is not resolving. Typo? Aborting.${ENDCOLOR}"
        exit 2
      fi

      # Log STDERR and STDOUT to $LOGFILE if specified
      if [ -n "$LOGFILE" ]; then
        echo -e "${GREEN}Connecting to $HOST ...${ENDCOLOR}" 2>&1 | tee -a "$LOGFILE"
        ssh -n -o ConnectTimeout=10 "${SSH_PARAMS}" "$SSH_USER"@"$HOST" "${COMMANDPART}" 2>&1 | tee -a "$LOGFILE"

        # Test if ssh-command was successful
        # shellcheck disable=SC2181
        if [ "$?" -ne 0 ]; then
          echo -n -e "${RED}Command was NOT successful on $HOST ... ${ENDCOLOR}" 2>&1 | tee -a "$LOGFILE"

          # Shall we proceed or not?
          if [ "$ABORT" = "YES" ]; then
            echo -n -e "${RED}Aborting.${ENDCOLOR}\n" 2>&1 | tee -a "$LOGFILE"
            exit 1
          else
            echo -n -e "${GREEN}Proceeding, as configured.${ENDCOLOR}\n" 2>&1 | tee -a "$LOGFILE"
          fi
        fi

      else

        echo -e "${GREEN}Connecting to $HOST ...${ENDCOLOR}"
        ssh -n -o ConnectTimeout=10 "${SSH_PARAMS}" "$SSH_USER"@"$HOST" "${COMMANDPART}"

        # Test if ssh-command was successful
        # shellcheck disable=SC2181
        if [ "$?" -ne 0 ]; then
          echo -n -e "${RED}Command was NOT successful on $HOST ... ${ENDCOLOR}"

          # Shall we proceed or not?
          if [ "$ABORT" = "YES" ]; then
            echo -n -e "${RED}Aborting.${ENDCOLOR}\n"
            exit 1
          else
            echo -n -e "${GREEN}Proceeding, as configured.${ENDCOLOR}\n"
          fi
        fi

      fi

    done < "$HOSTLIST"

  else
    echo -e "${RED}Hostlist \"$HOSTLIST\" is empty. Exiting.${ENDCOLOR}"
    exit 1
  fi

else
  echo -e "${RED}Hostlist \"$HOSTLIST\" is not readable. Exiting.${ENDCOLOR}"
  exit 1
fi