Show real memory usage (working set) per Docker container, excluding page cache

container-mem.sh

#!/bin/bash
# Show real memory usage (working set) per container
# working set = memory.current - inactive_file (excludes reclaimable page cache)

printf "%-30s %10s %10s %10s\n" "CONTAINER" "TOTAL" "CACHE" "WORKING SET"
printf "%-30s %10s %10s %10s\n" "---------" "-----" "-----" "-----------"

docker ps --format '{{.ID}} {{.Names}}' | while read id name; do
    cgroup=$(docker inspect --format '{{.Id}}' "$id")

    # Try cgroup v2 first, fall back to v1
    mem_current="/sys/fs/cgroup/system.slice/docker-${cgroup}.scope/memory.current"
    mem_stat="/sys/fs/cgroup/system.slice/docker-${cgroup}.scope/memory.stat"

    if [ ! -f "$mem_current" ]; then
        mem_current="/sys/fs/cgroup/memory/docker/${cgroup}/memory.usage_in_bytes"
        mem_stat="/sys/fs/cgroup/memory/docker/${cgroup}/memory.stat"
    fi

    if [ ! -f "$mem_current" ]; then
        printf "%-30s %10s\n" "$name" "N/A"
        continue
    fi

    total=$(cat "$mem_current")
    inactive_file=$(grep '^inactive_file' "$mem_stat" 2>/dev/null | awk '{print $2}')
    inactive_file=${inactive_file:-0}
    working_set=$(( total - inactive_file ))

    printf "%-30s %10s %10s %10s\n" \
        "$name" \
        "$(numfmt --to=iec $total)" \
        "$(numfmt --to=iec $inactive_file)" \
        "$(numfmt --to=iec $working_set)"
done