No-frills bash script to get memory utilization of your kubernetes cluster. depends on jq

show-cluster-utilization.sh

#!/bin/bash

# The MIT License (MIT)

# Copyright (c) 2015 Magnus Kulke <mkulke at gmail dot 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.

# USAGE:
#
# To specify clusters or contexts, set the KUBECTL env before calling:
# KUBECTL="kubectl --context=myothercontext" ./show-cluster-utilization.sh

set -e
set -o pipefail

KUBECTL=${KUBECTL:-kubectl}

function parse_units {
  read UNIT_STRING
  echo ${UNIT_STRING} | sed 's/Gi/ * 1024 Mi/g;s/Mi/ * 1024 Ki/g;s/Ki/ * 1024/g' | bc
}

function to_mb {
  read BYTES
  echo ${BYTES} | awk '{printf "%d", $1 / 1024 / 1024}'
}

declare -a NODE_NAMES=($(${KUBECTL} get nodes -o json | jq -r \
'.items | map(.metadata.name) | join(" ")'))
declare -a CAPACITIES=($(${KUBECTL} get nodes -o json \
| jq -r '.items | map(.status.capacity.memory) | join(" ")'))
PODS=$(${KUBECTL} get --all-namespaces pods -o json)

TABLE="Node Used Capacity ¯\_(ツ)_/¯ Percentage"

for i in "${!NODE_NAMES[@]}"
do
  NODE_NAME=${NODE_NAMES[$i]}
  CAPACITY=$(echo "${CAPACITIES[$i]}" | parse_units | to_mb)
  NODE_PODS=$(echo "${PODS}" | jq -r --arg node ${NODE_NAME} \
    '.items | map(select(.spec.nodeName == $node or .spec.host == $node))')
  HAS_NULL_LIMIT=$(echo "${NODE_PODS}" | jq -r \
    'map(.spec.containers | map(.resources.limits == null) | any) | any')
  if [ "${HAS_NULL_LIMIT}" == "true" ]
  then
    NA_NOTE="* Some containers do not have memory limits specificed, hence N/A."
    ROW="${NODE_NAME} N/A N/A N/A N/A"
  else
    POD_LIMITS=$(echo "${NODE_PODS}" | jq -r \
      'map(.spec.containers | map(.resources.limits.memory) | join(" + ")) | join(" + ")')
    TOTAL=$(echo "${POD_LIMITS}" | parse_units | to_mb)
    PERCENTAGE=$(echo "${TOTAL} ${CAPACITY}" | awk '{printf "%d", $1 / $2 * 100}')
    BAR_FULL=$(echo "(${PERCENTAGE} + 5) / 10" | bc)
    BAR_EMPTY=$(echo "10 - ${BAR_FULL}" | bc)
    printf -v full %${BAR_FULL}s
    printf -v empty %${BAR_EMPTY}s
    BAR=$(printf '%s%s' "${full// /#}${empty// /-}")
    ROW="${NODE_NAME} ${TOTAL}Mi ${CAPACITY}Mi [${BAR}] ${PERCENTAGE}%"
  fi
  TABLE="${TABLE}\n${ROW}"
done

echo -e "${TABLE}" | column -t -s ' '
if [ "${NA_NOTE}" != "" ]
then
  echo "${NA_NOTE}"
fi