monitor docker memory usage by each container code example

Example: how to get docker stats using shell script

#!/bin/bash

# This script is used to complete the output of the docker stats command.
# The docker stats command does not compute the total amount of resources (RAM or CPU)

# Get the total amount of RAM, assumes there are at least 1024*1024 KiB, therefore > 1 GiB
HOST_MEM_TOTAL=$(grep MemTotal /proc/meminfo | awk '{print $2/1024/1024}')

# Get the output of the docker stat command. Will be displayed at the end
# Without modifying the special variable IFS the ouput of the docker stats command won't have
# the new lines thus resulting in a failure when using awk to process each line
IFS=;
DOCKER_STATS_CMD=`docker stats --no-stream --format "table {{.MemPerc}}\t{{.CPUPerc}}\t{{.MemUsage}}\t{{.Name}}"`

SUM_RAM=`echo $DOCKER_STATS_CMD | tail -n +2 | sed "s/%//g" | awk '{s+=$1} END {print s}'`
SUM_CPU=`echo $DOCKER_STATS_CMD | tail -n +2 | sed "s/%//g" | awk '{s+=$2} END {print s}'`
SUM_RAM_QUANTITY=`LC_NUMERIC=C printf %.2f $(echo "$SUM_RAM*$HOST_MEM_TOTAL*0.01" | bc)`

# Output the result
echo $DOCKER_STATS_CMD
echo -e "${SUM_RAM}%\t\t\t${SUM_CPU}%\t\t${SUM_RAM_QUANTITY}GiB / ${HOST_MEM_TOTAL}GiB\tTOTAL"