Munin contributed plugins

#!/bin/bash

set -e

: << =cut

=head1 NAME

loggrepx - Counts the number of matching log lines by log file

=head1 DESCRIPTION

This plugin is somewhat of a bash port of the original loggrep plugin,

except that it displays a breakdown of matches per file, rather than

aggregating matches across all files. It is intended to answer the

question, "Which of my logs are reporting concerning events right now?"

=head1 CONFIGURATION

The plugin can be included multiple times to create graphs for various

differing kinds of information in your log files. For example, you may

want to monitor the occurrence of 5xx errors in your webserver logs, but

also the occurrence of alert|critical|emergency entries in your syslog.

You can accomplish this by linking the plugin twice and providing

different criteria for each instance.

Note that most instances will probably work best when run as root, since

log files are usually (or at least should be) controlled with strict

permissions.

Available config options include the following:

 env.logfiles         - Files to grep (shellglob) (required)

 env.regex            - Regex to look for (required)

 env.title            - Graph title

 env.warning          - Default warning level

 env.critical         - Default critical level

 env.[field]_label    - Label to use for a specific logfile

 env.[field]_warning  - Warning level for specific logfile

 env.[field]_critical - Critical level for specific logfile

NOTE: for any variable with [field] in it, [field] is derived from the

full logfile path by simply removing the preceding slash and replacing

all non-alphanumerics with underscores. For example, the "warning" field

for the logfile F</var/log/nginx/errors.log> would be

F<var_log_nginx_errors_log_warning>.

One good way to get these names is to run C<munin-run [plugin-name]>

after you've configured the required variables and then just copy/paste

the names from the output.

=head1 AUTHOR

Kael Shipman <kael.shipman@gmail.com>

=head1 LICENSE

Copyright 2018 Kael Shipman<kael.shipman@gmail.com>

Permission is hereby granted, free of charge, to any person obtaining a

copy of this software and associated documentation files (the "Software"),

to deal in the Software without restriction, including without limitation

the rights to use, copy, modify, merge, publish, distribute, sublicense,

and/or sell copies of the Software, and to permit persons to whom the

Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included

in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR

OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,

ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

OTHER DEALINGS IN THE SOFTWARE.

=head1 MAGIC MARKERS

 #%# family=manual

=cut

. "$MUNIN_LIBDIR/plugins/plugin.sh"

LOGFILES="$(IFS= ; for f in $logfiles; do echo "$f"; done)"

title="${title:-Log Matches}"

function config() {

    echo "graph_title ${title}"

    echo "graph_args --base 1000 -l 0"

    echo "graph_vlabel ${title}"

    echo "graph_category other"

    echo "graph_info Lists number of times the given regex is matched in the given log files per period"

    local var_prefix var logfile lbl

    while read -u 3 -r logfile; do

        var_prefix="$(echo "$logfile" | sed -r 's/^[^a-zA-Z]+//g' | sed -r 's/[^a-zA-Z0-9]+/_/g')"

        var="${var_prefix}_label"

        lbl="${!var:-$logfile}"

        echo "$var_prefix.label $lbl"

        print_warning "$var_prefix"

        print_critical "$var_prefix"

        echo "$var_prefix.info Lines that match '${regex}' in log file '$logfile'"

    done 3< <(echo "$LOGFILES")

}

function fetch() {

    # Load state

    touch "$MUNIN_STATEFILE"

    local curstate="$(cat "$MUNIN_STATEFILE")"

    local nextstate=()

    local var_prefix logfile prvlines curlines matches

    while read -u 3 -r logfile; do

        # Convert current logfile path to variable prefix

        var_prefix="$(echo "$logfile" | sed -r 's/^[^a-zA-Z]+//g' | sed -r 's/[^a-zA-Z0-9]+/_/g')"

        # Get running number of lines to determine whether or not the file may have been rotated

        prvlines="$(echo "$curstate" | grep "^${var_prefix}_lines=" | cut -f 2 -d "=")"

        if [ -z "$prvlines" ]; then

            prvlines=0

        fi

        # Get the current number of lines in the file

        curlines="$(wc -l < "$logfile")"

        if [ -z "$curlines" ]; then

            curlines=0

        fi

        # If the current line count is less than the previous line count, we've probably rotated.

        # Reset to 0.

        if [ "$curlines" -lt "$prvlines" ]; then

            prvlines=0

        else

            prvlines=$((prvlines + 1))

        fi

        # Get current number of incidents

        matches="$(tail -n +"$prvlines" "$logfile" | grep -Ec "${regex}" || true)"

        # Echo the value

        echo "$var_prefix.value $matches"

        # Push onto next state

        nextstate+=("${var}_lines=$curlines")

    done 3< <(echo "$LOGFILES")

    # Write state to munin statefile

    (IFS=$'\n'; echo "${nextstate[*]}" > "$MUNIN_STATEFILE")

    return 0

}

case "$1" in

    config) config ;;

    *) fetch ;;

esac