#!/bin/sh

# ########################################################################
# This program is part of $PROJECT_NAME$
# License: GPL License (see COPYING)
# Authors:
#  Baron Schwartz, Roman Vynar
# ########################################################################

# ########################################################################
# Redirect STDERR to STDOUT; Nagios doesn't handle STDERR.
# ########################################################################
exec 2>&1

# ########################################################################
# Set up constants, etc.
# ########################################################################
STATE_OK=0
STATE_WARNING=1
STATE_CRITICAL=2
STATE_UNKNOWN=3
STATE_DEPENDENT=4

# ########################################################################
# Run the program.
# ########################################################################
main() {
   # Get options
   for o; do
      case "${o}" in
         -C)              shift; OPT_CHEK="${1}"; shift; ;;
         -c)              shift; OPT_CRIT="${1}"; shift; ;;
         --defaults-file) shift; OPT_DEFT="${1}"; shift; ;;
         -H)              shift; OPT_HOST="${1}"; shift; ;;
         -l)              shift; OPT_USER="${1}"; shift; ;;
         -L)              shift; OPT_LOPA="${1}"; shift; ;;
         -p)              shift; OPT_PASS="${1}"; shift; ;;
         -P)              shift; OPT_PORT="${1}"; shift; ;;
         -S)              shift; OPT_SOCK="${1}"; shift; ;;
         -w)              shift; OPT_WARN="${1}"; shift; ;;
         --version)       grep -A2 '^=head1 VERSION' "$0" | tail -n1; exit 0 ;;
         --help)          perl -00 -ne 'm/^  Usage:/ && print' "$0"; exit 0 ;;
         -*)              echo "Unknown option ${o}.  Try --help."; exit 1; ;;
      esac
   done
   OPT_CHEK="${OPT_CHEK:-idle_blocker_duration}"
   if [ -e '/etc/nagios/mysql.cnf' ]; then
      OPT_DEFT="${OPT_DEFT:-/etc/nagios/mysql.cnf}"
   fi
   if is_not_sourced; then
      if [ -n "$1" ]; then
         echo "WARN spurious command-line options: $@"
         exit 1
      fi
   fi
   NOTE="UNK could not find information about transactions"

   local TEMP=$(mktemp -t "${0##*/}.XXXXXX") || exit $?
   trap "rm -f '${TEMP}' >/dev/null 2>&1" EXIT

   case "${OPT_CHEK}" in
      idle_blocker_duration)
         OPT_WARN=${OPT_WARN:-60}
         OPT_CRIT=${OPT_CRIT:-600}
         OUTPUT=$(mysql_exec "
            SELECT MAX(COALESCE(p.time, 0)) AS idle_in_trx,
                   p.id,
                   CONCAT(p.user, '@', p.host) AS userhost
            FROM       INFORMATION_SCHEMA.INNODB_LOCK_WAITS AS w
            INNER JOIN INFORMATION_SCHEMA.INNODB_TRX        AS b ON  b.trx_id = w.blocking_trx_id
            INNER JOIN INFORMATION_SCHEMA.INNODB_TRX        AS r ON  r.trx_id = w.requesting_trx_id
            LEFT  JOIN INFORMATION_SCHEMA.PROCESSLIST       AS p ON  p.id     = b.trx_mysql_thread_id AND p.command = 'Sleep'
            GROUP BY p.id, p.user, p.host
            ORDER BY idle_in_trx DESC LIMIT 1" 2>"${TEMP}")
         if [ "$?" != 0 ]; then
            if grep "Unknown table" "${TEMP}" >/dev/null 2>&1; then
               # The I_S tables don't exist.
               NOTE="OK The INFORMATION_SCHEMA.INNODB_% tables don't exist."
            else
               cat "${TEMP}"
            fi
         elif [ -z "${OUTPUT}" ]; then
            OUTPUT=0
         fi
         ;;
      waiter_count)
         OPT_WARN=${OPT_WARN:-10}
         OPT_CRIT=${OPT_CRIT:-25}
         OUTPUT=$(mysql_exec "
            SELECT COUNT(DISTINCT REQUESTING_TRX_ID) AS cnt
            FROM   INFORMATION_SCHEMA.INNODB_LOCK_WAITS AS w" 2>"${TEMP}")
         if [ "$?" != 0 ]; then
            if grep "Unknown table" "${TEMP}" >/dev/null 2>&1; then
               # The I_S tables don't exist.
               mysql_exec "SHOW /*!50000 ENGINE*/ INNODB STATUS\G" > "${TEMP}" || exit $?
               OUTPUT=$(get_waiter_count "${TEMP}")
            else
               cat "${TEMP}"
            fi
         fi
         ;;
      max_duration)
         OPT_WARN=${OPT_WARN:-60}
         OPT_CRIT=${OPT_CRIT:-600}
         OUTPUT=$(mysql_exec "
            SET @@time_zone='SYSTEM';
            SELECT   UNIX_TIMESTAMP() - UNIX_TIMESTAMP(t.trx_started),
                     p.id,
                     CONCAT(p.user, '@', p.host)
            FROM     INFORMATION_SCHEMA.INNODB_TRX  AS t
            JOIN     INFORMATION_SCHEMA.PROCESSLIST AS p ON p.id = t.trx_mysql_thread_id
            ORDER BY t.trx_started LIMIT 1" 2>"${TEMP}")
         if [ "$?" != 0 ]; then
            if grep "Unknown table" "${TEMP}" >/dev/null 2>&1; then
               # The I_S tables don't exist.
               mysql_exec "SHOW /*!50000 ENGINE*/ INNODB STATUS\G" > "${TEMP}" || exit $?
               OUTPUT=$(get_longest_trx "${TEMP}")
               if [ -z "${OUTPUT}" ]; then
                  OUTPUT=0
               fi
            else
               cat "${TEMP}"
            fi
         elif [ -z "${OUTPUT}" ]; then
            OUTPUT=0
         fi
         ;;
      *)
         echo "Unknown value for -C: '${OPT_CHEK}'. Consult the documentation.";
         exit 1;
         ;;
   esac

   # $OUTPUT now contains either an empty string or three words: 1) Age of
   # oldest transaction, 2) thread ID of oldest transaction, 3) user info.
   if [ -n "${OUTPUT}" ]; then
      LEVEL="$(echo ${OUTPUT} | awk '{print $1}')"
      INFO="$(echo ${OUTPUT} | awk '{print "(thread "$2" by "$3")"}')"

      case "${OPT_CHEK}" in
         idle_blocker_duration)
            NOTE="longest blocking idle transaction sleeps for ${LEVEL:-UNKNOWN} seconds"
            ;;
         waiter_count)
            NOTE="${LEVEL:-UNKNOWN} transactions in LOCK WAIT status"
            INFO=""
            ;;
         max_duration)
            NOTE="longest transaction active for ${LEVEL:-UNKNOWN} seconds"
            ;;
      esac
      if [ "${LEVEL:-0}" -gt "${OPT_CRIT}" ]; then
         NOTE="CRIT $NOTE $INFO"
      elif [ "${LEVEL:-0}" -gt "${OPT_WARN}" ]; then
         NOTE="WARN $NOTE $INFO"
      else
         NOTE="OK $NOTE"
      fi
   fi
   echo $NOTE
}

# ########################################################################
# Execute a MySQL command.
# ########################################################################
mysql_exec() {
   mysql ${OPT_DEFT:+--defaults-file="${OPT_DEFT}"} \
      ${OPT_LOPA:+--login-path="${OPT_LOPA}"} \
      ${OPT_HOST:+-h"${OPT_HOST}"} ${OPT_PORT:+-P"${OPT_PORT}"} \
      ${OPT_USER:+-u"${OPT_USER}"} ${OPT_PASS:+-p"${OPT_PASS}"} \
      ${OPT_SOCK:+-S"${OPT_SOCK}"} -ss -e "$1"
}

# ########################################################################
# Gets max txn time in SHOW INNODB STATUS. File is $1.
# ########################################################################
get_longest_trx() {
   awk '
      BEGIN {
         maxtime = 0;
         thread  = 0;
         userinfo = "nobody";
      }
      /^TRANSACTIONS$/ {
         tseen = 1;
      }
      {
         if ( tseen == 1 && $0 ~ /^---TRANSACTION.*[0-9] sec/ ) {
            if ( $2 ~ /,/ ) {
               time = $4;
            }
            else {
               time = $5;
            }
         }
         if ( tseen == 1 && $0 ~ /^MySQL thread id/ ) {
            if ( time > maxtime ) {
               maxtime = time;
               thread  = substr($4, 1, length($4) - 1);
               match($0, /query id [0-9]+ .+/);
               userinfo = substr($0, RSTART, RLENGTH);
               split(userinfo, a, " ");
               userinfo = a[5]"@"a[4];
            }
         }
      }
      END {
         print maxtime, thread, userinfo;
      }
      ' "${1}"
}

# ########################################################################
# Counts the number of LOCK WAIT in SHOW INNODB STATUS. File is $1.
# ########################################################################
get_waiter_count() {
   awk '
      BEGIN {
         lock_waits = 0;
      }
      /^TRANSACTIONS$/ {
         tseen = 1;
      }
      {
         if ( tseen == 1 && $0 ~ /TRX HAS BEEN WAITING/ ) {
            lock_waits++;
         }
      }
      END {
         print lock_waits;
      }
      ' "${1}"
}

# ########################################################################
# Determine whether this program is being executed directly, or sourced/included
# from another file.
# ########################################################################
is_not_sourced() {
   [ "${0##*/}" = "pmp-check-mysql-innodb" ] || [ "${0##*/}" = "bash" -a "$_" = "$0" ]
}

# ########################################################################
# Execute the program if it was not included from another file.
# This makes it possible to include without executing, and thus test.
# ########################################################################
if is_not_sourced; then
   OUTPUT=$(main "$@")
   EXITSTATUS=$STATE_UNKNOWN
   case "${OUTPUT}" in
      UNK*)  EXITSTATUS=$STATE_UNKNOWN;  ;;
      OK*)   EXITSTATUS=$STATE_OK;       ;;
      WARN*) EXITSTATUS=$STATE_WARNING;  ;;
      CRIT*) EXITSTATUS=$STATE_CRITICAL; ;;
   esac
   echo "${OUTPUT}"
   exit $EXITSTATUS
fi

# ############################################################################
# Documentation
# ############################################################################
: <<'DOCUMENTATION'
=pod

=head1 NAME

pmp-check-mysql-innodb - Alert on problems inside InnoDB.

=head1 SYNOPSIS

  Usage: pmp-check-mysql-innodb [OPTIONS]
  Options:
    -C CHECK        What to alert on; default idle_blocker_duration.
                    Other options: waiter_count, max_duration.
    -c CRIT         Critical threshold; default varies.
    --defaults-file FILE Only read mysql options from the given file.
                    Defaults to /etc/nagios/mysql.cnf if it exists.
    -H HOST         MySQL hostname.
    -l USER         MySQL username.
    -L LOGIN-PATH   Use login-path to access MySQL (with MySQL client 5.6).
    -p PASS         MySQL password.
    -P PORT         MySQL port.
    -S SOCKET       MySQL socket file.
    -w WARN         Warning threshold; default varies.
    --help          Print help and exit.
    --version       Print version and exit.
  Options must be given as --option value, not --option=value or -Ovalue.
  Use perldoc to read embedded documentation with more details.

=head1 DESCRIPTION

This Nagios plugin alerts on various aspects of InnoDB status in several ways,
depending on the value of the -C option:

=over

=item idle_blocker_duration

This is the default behavior.  It alerts when a long-running transaction is
blocking another, and the blocker is idle (Sleep).  The threshold is based on
how long the transaction has been idle.  Long-running idle transactions that
have acquired locks but not released them are a frequent cause of application
downtime due to lock wait timeouts and rollbacks, especially because
applications are often not designed to handle such errors correctly.  The
problem is usually due to another error that causes a transaction not to be
committed, such as performing very long tasks in the application while holding
the transaction open.

This check examines the INFORMATION_SCHEMA tables included with InnoDB version
1.0 and newer. The default critical level is 600, and warning is 60.  If the
tables do not exist, the exit status is OK, with a note that the tables do not
exist.

=item waiter_count

Alerts if too many transactions are in LOCK WAIT status. Uses information from
SHOW ENGINE INNODB STATUS if the INFORMATION_SCHEMA tables are not available.
The default critical level is 25, and warning is 10.

=item max_duration

Alerts if any transaction is too old.  Uses information from SHOW ENGINE INNODB
STATUS if the INFORMATION_SCHEMA tables are not available. The default critical
level is 600, and warning is 60.

=back

=head1 PRIVILEGES

This plugin executes the following commands against MySQL:

=over

=item *

C<SHOW ENGINE INNODB STATUS>.

=item *

C<SELECT> against the C<INFORMATION_SCHEMA> InnoDB transaction and lock tables.

=back

This plugin executes no UNIX commands that may need special privileges.

=head1 COPYRIGHT, LICENSE, AND WARRANTY

This program is copyright 2012-$CURRENT_YEAR$ Baron Schwartz, 2012-$CURRENT_YEAR$ Percona Inc.
Feedback and improvements are welcome.

THIS PROGRAM IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation, version 2.  You should have received a copy of the GNU General
Public License along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.

=head1 VERSION

$PROJECT_NAME$ pmp-check-mysql-innodb $VERSION$

=cut

DOCUMENTATION
