apt-upgradable

#!/bin/bash
#
# For more information either run `munindoc apt-upgradable` or read
# `apt-upgradable.pod`
#
#%# family=auto
#%# capabilities=autoconf

APTITUDE=${aptitude_path:-/usr/bin/aptitude}
UPG_COLOR=${upgrades_color:-00ff00}
ESS_COLOR=${essential_color:-ff0000}
IMP_COLOR=${important_color:-000000}
IMPORTANT_PKGS=${important:-""}
ARR_IMPORTANT=($IMPORTANT_PKGS)

CACHE="/var/lib/munin-node/plugin-state/$(whoami)/apt_upgradable"
if [ ! -d ${CACHE} ]; then
    mkdir ${CACHE}
fi

function in_array() {
   local x
   ENTRY=$1
   shift 1
   ARRAY=( "$@" )
   [ -z "${ARRAY}" ] && return 1
   [ -z "${ENTRY}" ] && return 1
   for x in ${ARRAY[@]}; do
      [ "${x}" == "${ENTRY}" ] && return 0
   done
   return 1
}

###
# Returns the content of a file in the cache. If not available, return U
#
# Params
#    $1 The filename (relative to the cache dir)
##
function cached() {
    local fname
    fname=$1
    if [ -f ${CACHE}/${fname} ]; then
        echo $(cat ${CACHE}/${fname})
    else
        echo U
    fi
}

case $1 in
    autoconf)
        if [ -x ${APTITUDE} ] ; then
            echo "yes"
        else
            echo "no ('${APTITUDE}' is not executable. You can override the path using the 'aptitude_path' environment variable)!"
        fi
        exit 0;;
    config)
        echo "graph_title Available APT upgrades"
        echo "graph_vlabel packages"
        echo "graph_category system"
        echo "graph_printf %3.0lf"
        echo "graph_args --base 1000 --lower-limit 0"
        echo "upgrades.label Upgradable packages"
        echo "upgrades.draw AREA"
        echo "upgrades.warning 15"
        echo "upgrades.critical 30"
        echo "upgrades.colour ${UPG_COLOR}"
        echo "essential.label Essential upgrades"
        echo "essential.draw STACK"
        echo "essential.warning 5"
        echo "essential.critical 10"
        echo "essential.colour ${ESS_COLOR}"
        if [ "${#ARR_IMPORTANT[@]}" -ne 0 ]; then
            echo "important.label Important upgrades"
            echo "important.draw LINE"
            echo "important.warning 0:0"
            echo "important.colour ${IMP_COLOR}"
        fi
    exit 0;;
esac

ESSENTIAL=$(cached essential)
UPGRADES=$(cached upgrades)
IMPORTANT=$(cached important)

echo "essential.value $ESSENTIAL"
echo "upgrades.value $UPGRADES"
echo "important.value $IMPORTANT"

pgrep apt
if [[ "$?" == "0" ]]; then
    # Another instance of apt is running. This should not break this script. We
    # will simply return the cached values.
    exit 0
fi

# Now run the value updated in background. A lock file is created to avoid
# running multiple instances. This ensures that the munin plugin returns fast,
# so munin can continue processing other plugins. This also means that the
# values are always delayed by one execution of this plugin, and that the first
# value will be unknown. But this is not a real-time plugin, so that's okay.
if [ ! -f ${CACHE}/lock ]; then
    {
        touch ${CACHE}/lock
        NEW_ESS=$(${APTITUDE} search "?and(?and(?not(?automatic), ?upgradable), ?essential)" | wc -l)
        NEW_UPG=$(${APTITUDE} search "?and(?and(?not(?automatic), ?upgradable), ?not(?essential))" | wc -l)
        NEW_IMP="U"
        if [ "${#ARR_IMPORTANT[@]}" -ne 0 ]; then
            NUM_IMPORTANT=0
            for pkg in $($APTITUDE -F "%p" search ~U); do
                in_array ${pkg} "${ARR_IMPORTANT[@]}"
                RET=$?
                if [ "${RET}" -eq 0 ]; then
                    NUM_IMPORTANT=$(($NUM_IMPORTANT+1))
                fi
            done
            NEW_IMP=${NUM_IMPORTANT}
        fi

        # Try to write all values in one atomic operation before removing the
        # lock. This way we should either get all or no values and should avoid
        # interleaving of multiple processes in parallel.
        # NOTE: In the case of parallel processes, the last one to finish wins.
        {
            echo $NEW_ESS > ${CACHE}/essential
            echo $NEW_UPG > ${CACHE}/upgrades
            echo $NEW_IMP > ${CACHE}/important
        } && rm ${CACHE}/lock
    } &
else
    # Either another process is running (highly unlikely, except on EXTREMELY
    # high load) or something went wrong (more likely). In order to avoid
    # graphs with incorrect data, we will reset them to "UNKNOWN". This should
    # trigger the interest of a sysadmin to see what's going on.
    echo Lock file ${CACHE}/lock exists. Not updating the APT values. 1>&2
    echo U > ${CACHE}/essential
    echo U > ${CACHE}/upgrades
    echo U > ${CACHE}/important
fi