Munin contributed plugins

#!/bin/bash

# -*- bash -*-

: <<=cut

=head1 NAME

nginx error - Munin plugin to monitor nginx error rates (http status codes per minute).

=head1 APPLICABLE SYSTEMS

Any host running nginx, with bash version > 4.0

=head1 CONFIGURATION

This shows the default configuration of this plugin.  You can override

the log file path and the logpattern.

Additionally you may want to adjust 'group' (or 'user') based on the

permissions required for reading the log file.

  [nginx_error]

        group          adm

	env.logpath    /var/log/nginx

	env.logpattern a.*.log

	Nginx must also be configured to log accesses in "combined" log format (default)

=head1 USAGE

Link this plugin to /etc/munin/plugins/ and restart the munin-node.

This plugin also can be used like wildcard-plugin for monitoring particular virtual host log.

E.g.

    ln -s /usr/share/munin/plugins/nginx_error /etc/munin/plugins/nginx_error_mydomaincom

will parse the log file /var/log/nginx/a.mydomaincom.log

You can change 'env.logpattern' using asterisk ('*') to match your logs filenames.

'env.logpattern' is ignored for a non-symlink configuration.

=head1 INTERPRETATION

The plugin shows nginx http "error" status rates by parsing access log.

=head1 MAGIC MARKERS

 #%# family=auto

 #%# capabilities=autoconf

=head1 BUGS

None known.

=head1 VERSION

1.1 - 2018/01/20

      * add 'dirty config' capability support

      * fix shell style issues reported by shellcheck

      * improve readability of symlink configuration code

1.0 - 2017/02/21

=head1 AUTHOR

vovansystems@gmail.com, 2013

=head1 LICENSE

GPLv3

=cut

set -eu

# default environment variable values

logpath=${logpath:-/var/log/nginx}

# derive the name of the log file from a potential symlink-configured virtual host

script_name=$(basename "$0")

plugin_suffix=${script_name#nginx_error}

if [ -n "${plugin_suffix#_}" ]; then

  # a domain was given via symlink configuration: adjust the logpattern

  domain=${plugin_suffix#_}

  # default logpattern for symlink configuration mode

  logpattern=${logpattern:-a.*.log}

  log_filename=${logpattern/\*/$domain}

else

  log_filename='access.log'

fi

log="$logpath/$log_filename"

# declaring an array with http status codes, we are interested in

declare -A http_codes

http_codes[400]='Bad Request'

http_codes[401]='Unauthorized'

http_codes[403]='Forbidden'

http_codes[404]='Not Found'

http_codes[405]='Method Not Allowed'

http_codes[406]='Not Acceptable'

http_codes[408]='Request Timeout'

http_codes[429]='Too Many Requests'

http_codes[499]='Client Connection Terminated'

http_codes[500]='Internal Server Error'

http_codes[502]='Bad Gateway'

http_codes[503]='Service Unavailable'

# parse error counts from log file

do_fetch () {

  local count status_code

  declare -A line_counts

  values="$(awk '{print $9}' "$log" | sort | uniq -c)"

  # Log files may be empty due to logrotation

  if [ -n "$values" ]; then

    while read -r count status_code; do

      line_counts[$status_code]=$count

    done <<< "$values"

  fi

  for status_code in "${!http_codes[@]}"; do

    echo "error${status_code}.value ${line_counts[$status_code]:-0}"

  done

}

do_config () {

  local status_code

  echo "graph_title $(basename "$log") - Nginx errors per minute"

  echo "graph_vlabel pages with http error codes / \${graph_period}"

  echo "graph_category webserver"

  echo "graph_period minute"

  echo "graph_info This graph shows nginx error rate per minute"

  for status_code in "${!http_codes[@]}"; do

    echo "error${status_code}.type DERIVE"

    echo "error${status_code}.min 0"

    echo "error${status_code}.label $status_code ${http_codes[$status_code]}"

  done

}

do_autoconf () {

  echo yes

}

case ${1:-} in

  config)

    do_config

    # support "dirty config" capability

    if [ "${MUNIN_CAP_DIRTYCONFIG:-0}" = "1" ]; then do_fetch; fi

    ;;

  autoconf)

    do_autoconf

    ;;

  '')

    do_fetch

    ;;

esac

exit $?