process_monitoring

#!/bin/sh

########################################################################
# process_monitoring: Munin Plugin for Monitoring Required Processes
#
#  This plugin belongs to the 'contrib' family, indicating it is community-maintained.
#%# family=contrib
#  This plugin supports Munin's autoconf feature for automatic configuration checks.
#%# capabilities=autoconf
#
#  Description:
#  This plugin monitors the presence and count of essential system
#  processes and configuration rules. Designed for use with Munin,
#  it reports the number of running instances or matching configurations,
#  such as iptables rules, ntpd, memcached, postgres (or postmaster),
#  apache2, and MySQL-compatible servers (mysqld / mariadbd).
#
#  It helps system administrators ensure that critical services are
#  running as expected. The plugin outputs a graph in Munin showing
#  the state of required processes.
#
#  Toggle targets:
#    Set the following global variables to 1 or 0 to enable or disable monitoring.
#    Default is 1 (enabled). You can edit them here or pass via environment
#    (e.g., in /etc/munin/plugin-conf.d using env.iptables=0).
#      iptables   = 1  # Monitor iptables rule presence
#      ntpd       = 1  # Monitor ntpd process
#      memcached  = 1  # Monitor memcached process
#      postgres   = 1  # Monitor postgres/postmaster process
#      mysql      = 1  # Monitor mysqld/mariadbd process
#      apache2    = 1  # Monitor apache2 process
#
#    Example: to disable iptables monitoring, set: iptables=0
#
#    You can also override these values via Munin plugin configuration:
#      /etc/munin/plugin-conf.d/local
#      [process_monitoring]
#      env.iptables=0
#      env.mysql=0
#
#    This allows you to manage settings without editing the plugin itself.
#    If both are defined, the environment variable (plugin-conf.d setting) takes precedence.
#
#  Author: id774 (More info: http://id774.net)
#  Source Code: https://github.com/id774/munin-plugins
#  License: The GPL version 3, or LGPL version 3 (Dual License).
#  Contact: idnanashi@gmail.com
#
#  Usage:
#      sudo ln -s /usr/local/share/munin/plugins/process_monitoring /etc/munin/plugins/process_monitoring
#
#      Then reload munin-node:
#      sudo systemctl restart munin-node
#
#  Example:
#      ./process_monitoring autoconf
#      ./process_monitoring config
#      ./process_monitoring
#
#  Note:
#      If your system requires privileges for listing firewall rules,
#      allow the munin user via sudoers, e.g.:
#      munin ALL=(root) NOPASSWD:/sbin/iptables
#
#  Version History:
#  v2.0 2025-09-23
#       Add simple per-target toggle via global variables with defaults.
#       Make autoconf conditional on toggles and suppress disabled fields in config/fetch.
#  v1.3 2025-09-15
#       Added GAUGE type definitions, raised graph ceiling to 50, and ensured PostgreSQL
#       compatibility by counting both postgres and legacy postmaster processes.
#  v1.2 2025-09-09
#       POSIX safe process counting via ps comm and simplified autoconf dependencies.
#  v1.1 2025-08-29
#       Add MySQL (mysqld / mariadbd) process monitoring (label: mysql).
#  v1.0 2025-03-26
#       Refactored for POSIX compliance. Added full header documentation,
#       improved readability and maintainability with English comments.
#  v0.1 2018-09-18
#       Initial version.
#
########################################################################

# --- Target toggles with sane defaults ---
# Allow override via environment (Munin plugin-conf env.*) or inline edits below.
: "${iptables:=1}"
: "${ntpd:=1}"
: "${memcached:=1}"
: "${postgres:=1}"
: "${mysql:=1}"
: "${apache2:=1}"

# Display full script header information extracted from the top comment block
usage() {
    awk '
        BEGIN { in_header = 0 }
        /^#{10,}$/ { if (!in_header) { in_header = 1; next } else exit }
        in_header && /^# ?/ {
            if ($0 ~ /^#%#/) next
            print substr($0, 3)
        }
    ' "$0"
    return 0
}

# --- Autoconf check ---
autoconf() {
    # Exit code flag for autoconf checks
    CONF_ERR=0

    # Check for required commands
    # Note: Do not require service binaries themselves (memcached, etc.)
    for cmd in ps grep awk; do
        command -v "$cmd" >/dev/null 2>&1 || CONF_ERR=1
    done

    # Only require iptables and sudo if iptables monitoring is enabled
    if [ "${iptables:-1}" -eq 1 ]; then
        command -v iptables >/dev/null 2>&1 || CONF_ERR=1
        # sudo may be required to list rules depending on policy
        command -v sudo >/dev/null 2>&1 || CONF_ERR=1
    fi

    if [ "$CONF_ERR" -eq 0 ]; then
        echo "yes"
    else
        echo "no"
    fi

    return 0
}

# --- Munin graph configuration output ---
config() {
    echo "graph_category processes"
    echo "graph_title Required processes"
    echo "graph_vlabel Number of required processes"
    echo "graph_args --lower-limit 0 --upper-limit 20"

    # Define label and graph style/type for each monitored service (conditionally)
    if [ "$iptables" -eq 1 ]; then
        echo "iptables.label iptables"
        echo "iptables.type GAUGE"
        echo "iptables.draw LINE2"
        echo "iptables.warning 1:"
        echo "iptables.critical 1:"
    fi

    if [ "$ntpd" -eq 1 ]; then
        echo "ntpd.label ntp"
        echo "ntpd.type GAUGE"
        echo "ntpd.draw LINE2"
        echo "ntpd.warning 1:"
        echo "ntpd.critical 1:"
    fi

    if [ "$memcached" -eq 1 ]; then
        echo "memcached.label memcached"
        echo "memcached.type GAUGE"
        echo "memcached.draw LINE2"
        echo "memcached.warning 1:"
        echo "memcached.critical 1:"
    fi

    if [ "$postgres" -eq 1 ]; then
        echo "postgres.label postgres"
        echo "postgres.type GAUGE"
        echo "postgres.draw LINE2"
        echo "postgres.warning 1:"
        echo "postgres.critical 1:"
    fi

    if [ "$mysql" -eq 1 ]; then
        echo "mysql.label mysql"
        echo "mysql.type GAUGE"
        echo "mysql.draw LINE2"
        echo "mysql.warning 1:"
        echo "mysql.critical 1:"
    fi

    if [ "$apache2" -eq 1 ]; then
        echo "apache2.label apache2"
        echo "apache2.type GAUGE"
        echo "apache2.draw LINE2"
        echo "apache2.warning 1:"
        echo "apache2.critical 1:"
    fi

    return 0
}

# --- Data collection helpers ---
# Count processes by exact command name using POSIX-safe ps
count_comm() {
    # Prints the count of processes whose command name exactly matches $1
    ps -e -o comm= | grep -c "^$1$"
}

# --- Data collection phase ---
fetch() {
    # Count iptables rules matching specific description
    if [ "$iptables" -eq 1 ]; then
        CMD=$(sudo iptables -vn -L 2>/dev/null | grep -c "SET name: SSH side: source")
        echo "iptables.value $CMD"
    fi

    if [ "$ntpd" -eq 1 ]; then
        CMD=$(count_comm ntpd)
        echo "ntpd.value $CMD"
    fi

    if [ "$memcached" -eq 1 ]; then
        CMD=$(count_comm memcached)
        echo "memcached.value $CMD"
    fi

    if [ "$postgres" -eq 1 ]; then
        CMD=$(ps -e -o comm= | grep -E -c "^(postgres|postmaster)$")
        echo "postgres.value $CMD"
    fi

    if [ "$mysql" -eq 1 ]; then
        CMD=$(ps -e -o comm= | grep -E -c "^(mysqld|mariadbd)$")
        echo "mysql.value $CMD"
    fi

    if [ "$apache2" -eq 1 ]; then
        CMD=$(count_comm apache2)
        echo "apache2.value $CMD"
    fi

    return 0
}

# Main entry point of the script
main() {
    case "$1" in
        -h|--help|-v|--version) usage ;;
        autoconf) autoconf ;;
        config) config ;;
        *) fetch ;;
    esac
    return $?
}

# Execute main function
main "$@"