get all docker constraints in variables

getdockerenv.sh

#!/bin/bash

# getdockerenv.sh v1.0
# 2021-06-23 - João Alves

# This script sets a group of variables that can be useful in a containerized environment
# It is specially tuned for docker but might (not tested) work in other environments

# Exported variables:
# CGROUPS - v1, v2, none
# DOCKER_CID - current id of docker container running or none
# DOCKER_CPUCONSTRAINT - 0 if not constrained, 1 if constrained
# DOCKER_CPU - Calculated value of cpu allocation (can have decimal part)
# DOCKER_CPU_INT - Calculated value of CPU allocation - only the integer part.
# DOCKER_MEMCONSTRAINT -
# DOCKER_MEMTOTAL - Calculated value of total memory (can have decimal part) in MB
# DOCKER_MEMTOTAL_INT - Calculated value of total memory in MB - only the integer part
# DOCKER_MEMFREE - Calculated value of current free memory (can have decimal part) in MB
# DOCKER_MEMFREE_INT - Calculated value of current free memory in MB - only the integer part
# DOCKER_MEMPERCFREE - Percentage of free mem

# Tested environments:
# - Not containerized
# - Docker 20.0
# - Cgroups v1 and v2

# Can be tested with:
#   Not containerized:
#     sh getdockerenv.sh
#   Inside container:
#     docker run -it -v $PWD/getdockerenv.sh:/getdockerenv.sh busybox:latest sh /getdockerenv.sh
#     docker run -it --cpus 1.5 -v $PWD/getdockerenv.sh:/getdockerenv.sh busybox:latest sh /getdockerenv.sh
#     docker run -it --memory 200M -v $PWD/getdockerenv.sh:/getdockerenv.sh busybox:latest sh /getdockerenv.sh
#     docker run -it --cpus 1.5 --memory 200M -v $PWD/getdockerenv.sh:/getdockerenv.sh busybox:latest sh /getdockerenv.sh

# If any arguments are passed to the command no echo will be produced.

set -e

# Cgroups and docker info
export CGROUPS
CGROUPS=v1
export DOCKER_CID
DOCKER_CID=$(grep '^/docker' /proc/1/cpuset | sed 's,/docker/\([0-9a-f]*\),\1,g')

if [ -z "$DOCKER_CID" ]; then
  DOCKER_CID=$(sed '/hostname/!d; s,.*/containers/\([^/]*\)/hostname.*,\1,g' /proc/self/mountinfo)
  CGROUPS=v2
fi
if [ -z "$DOCKER_CID" ]; then
  DOCKER_CID=none
  CGROUPS=none
fi

[ "$#" -gt 0 ] || echo "CGROUPS=$CGROUPS"
[ "$#" -gt 0 ] || echo "DOCKER_CID=$DOCKER_CID"

# CPU:
export DOCKER_CPUCONSTRAINT
DOCKER_CPUCONSTRAINT=0

docker_image_cpus=$(nproc)
docker_cpu_quota=$docker_image_cpus
docker_cpu_period=1

# cgroupsv1
if [ -f /sys/fs/cgroup/cpu/cpu.cfs_quota_us ] && [ -f /sys/fs/cgroup/cpu/cpu.cfs_period_us ]; then
  docker_cpu_quota=$(cat /sys/fs/cgroup/cpu/cpu.cfs_quota_us)
  docker_cpu_period=$(cat /sys/fs/cgroup/cpu/cpu.cfs_period_us)
  DOCKER_CPUCONSTRAINT=1
  if [ "$docker_cpu_quota" == "-1" ]; then
    docker_cpu_quota=$(echo "scale=1; $(nproc)*$docker_cpu_period" | bc)
    DOCKER_CPUCONSTRAINT=0
  fi
fi
# cgroupsv2
if [ -f /sys/fs/cgroup/cpu.max ]; then
    docker_cpu_quota=$(cut -d' ' -f1 /sys/fs/cgroup/cpu.max)
    docker_cpu_period=$(cut -d' ' -f2 /sys/fs/cgroup/cpu.max)
    DOCKER_CPUCONSTRAINT=1
    if [ "$docker_cpu_quota" == "max" ]; then
      docker_cpu_quota=$(echo "scale=1; $(nproc)*$docker_cpu_period" | bc)
      DOCKER_CPUCONSTRAINT=0
    fi
fi
docker_image_cpus=$(echo "scale=1; c=$docker_cpu_quota/$docker_cpu_period; if(c<1 && c>0) print 0; c" | bc)

export DOCKER_CPU
DOCKER_CPU="$docker_image_cpus"
export DOCKER_CPU_INT
DOCKER_CPU_INT="$(echo "$docker_image_cpus" | sed 's,^\([0-9]*\).*$,\1,g')"

[ "$#" -gt 0 ] || echo "DOCKER_CPUCONSTRAINT=$DOCKER_CPUCONSTRAINT"
[ "$#" -gt 0 ] || echo "DOCKER_CPU=$DOCKER_CPU"
[ "$#" -gt 0 ] || echo "DOCKER_CPU_INT=$DOCKER_CPU_INT"

# MEMORY:
export DOCKER_MEMCONSTRAINT

DOCKER_MEMCONSTRAINT=0
docker_image_memory_total=$(echo "scale=1; $(sed '/^MemTotal/!d; s,^.*:\s*\([0-9]*\)\s*.*,\1,g' /proc/meminfo)/1024" | bc)
docker_image_memory_free=$(echo "scale=1; $(sed '/^MemFree/!d; s,^.*:\s*\([0-9]*\)\s*.*,\1,g' /proc/meminfo)/1024" | bc)

# cgroupsv1
if [ -f /sys/fs/cgroup/memory/memory.limit_in_bytes ]; then
  if [ -f /sys/fs/cgroup/memory/memory.limit_in_bytes ] && [ -f /sys/fs/cgroup/memory/memory.usage_in_bytes ]; then
    docker_memory_total=$(cat /sys/fs/cgroup/memory/memory.limit_in_bytes)
    docker_memory_usage=$(cat /sys/fs/cgroup/memory/memory.usage_in_bytes)
    if [ "$docker_memory_total" -lt 8000000000000 ]; then
      docker_image_memory_total=$(echo "scale=1; $docker_memory_total/1024/1024" | bc)
      docker_image_memory_free=$(echo "scale=1; ($docker_memory_total-$docker_memory_usage)/1024/1024" | bc)
      DOCKER_MEMCONSTRAINT=1
    fi
  fi
fi

# cgroupsv2
if [ -f /sys/fs/cgroup/memory.max ]; then
  docker_memory_total=$(cat /sys/fs/cgroup/memory.max)
  if [ "$docker_memory_total" != "max" ]; then
    docker_image_memory_total=$(echo "scale=1; $docker_memory_total/1024/1024" | bc)
    docker_memory_usage=$(cat /sys/fs/cgroup/memory.current)
    docker_image_memory_free=$(echo "scale=1; ($docker_memory_total-$docker_memory_usage)/1024/1024" | bc)
    DOCKER_MEMCONSTRAINT=1
  fi
fi
docker_image_memory_percent=$(echo "scale=1; ($docker_image_memory_free)*100/$docker_image_memory_total" | bc)

export DOCKER_MEMTOTAL
DOCKER_MEMTOTAL="$docker_image_memory_total"
export DOCKER_MEMTOTAL_INT
DOCKER_MEMTOTAL_INT="$(echo "$docker_image_memory_total" | sed 's,^\([0-9]*\).*$,\1,g')"
export DOCKER_MEMFREE
DOCKER_MEMFREE="$docker_image_memory_free"
export DOCKER_MEMFREE_INT
DOCKER_MEMFREE_INT="$(echo "$docker_image_memory_free" | sed 's,^\([0-9]*\).*$,\1,g')"
export DOCKER_MEMPERCFREE
DOCKER_MEMPERCFREE="$docker_image_memory_percent"

[ "$#" -gt 0 ] || echo "DOCKER_MEMCONSTRAINT=$DOCKER_MEMCONSTRAINT"
[ "$#" -gt 0 ] || echo "DOCKER_MEMTOTAL=$DOCKER_MEMTOTAL"
[ "$#" -gt 0 ] || echo "DOCKER_MEMTOTAL_INT=$DOCKER_MEMTOTAL_INT"
[ "$#" -gt 0 ] || echo "DOCKER_MEMFREE=$DOCKER_MEMFREE"
[ "$#" -gt 0 ] || echo "DOCKER_MEMFREE_INT=$DOCKER_MEMFREE_INT"
[ "$#" -gt 0 ] || echo "DOCKER_MEMPERCFREE=$DOCKER_MEMPERCFREE"

#for v in CGROUPS DOCKER_CID DOCKER_CPUCONSTRAINT DOCKER_CPU DOCKER_CPU_INT DOCKER_MEMCONSTRAINT DOCKER_MEMTOTAL DOCKER_MEMTOTAL_INT DOCKER_MEMFREE DOCKER_MEMFREE_INT DOCKER_MEMPERCFREE ; do
#  echo $v=${!v}
#done