#!/bin/sh

# This script reproduces what the kubelet does to calculate
# memory.available relative to root cgroup. (Adapted from 
# https://kubernetes.io/examples/admin/resource/memory-available.sh)

memk=$(grep MemTotal /proc/meminfo)
memk=${memk##MemTotal: }
memk=${memk%% kB}
memb=$((memk * 1024))
used=$(cat /sys/fs/cgroup/memory/memory.usage_in_bytes)
inactive=$(grep total_inactive_file /sys/fs/cgroup/memory/memory.stat)
inactive=${inactive##* }
working=0
test "$used" -ge "$inactive" && working=$((memb - inactive))
availb=$((memb - working))
availk=$((availb / 1024))
availm=$((availk / 1024))
availg=$(echo "scale=1; $availm / 1024" | bc)

echo "capacity:   $memb"
echo "usage:      $used"
echo "inactive:   $inactive"
echo "working:    $working"
echo "available:  $availb"
echo "availableK: $availk"
echo "availableM: $availm"
echo "availableG: $availg"