Docker rates.sh

This prints out a table of instantaneous network bandwidth use.

#!/usr/bin/env bash
# Instantaneous per-container network rates (B/s). No extra packages.
INTERVAL=1
TMPDIR=${TMPDIR:-/tmp}
PREV="$TMPDIR/net.prev.$$.txt"
NOW="$TMPDIR/net.now.$$.txt"
OUT="$TMPDIR/net.out.$$.txt"

cleanup(){ rm -f "$PREV" "$NOW" "$OUT"; exit 0; }
trap cleanup INT TERM

collect() {
  target="$1"
  : > "$target"
  docker ps -q | while read -r id; do
    [ -z "$id" ] && continue
    name=$(docker inspect --format '{{.Name}}' "$id" 2>/dev/null | sed 's#/##')
    pid=$(docker inspect --format '{{.State.Pid}}' "$id" 2>/dev/null)
    if [ -r "/proc/$pid/net/dev" ]; then
      read rx tx < <(awk 'NR>2{rx+=$2;tx+=$10}END{print rx,tx}' /proc/"$pid"/net/dev 2>/dev/null || echo "0 0")
    else
      rx=0; tx=0
    fi
    # id<TAB>name<TAB>pid<TAB>rx<TAB>tx
    printf '%s\t%s\t%s\t%s\t%s\n' "$id" "$name" "$pid" "$rx" "$tx" >> "$target"
  done
}

# seed previous snapshot
collect "$PREV"
sleep "$INTERVAL"

while true; do
  ts=$(date +"%F %T")
  collect "$NOW"

  # load previous counters into associative arrays
  declare -A PRX PTX PNAME
  while IFS=$'\t' read -r id name pid rx tx; do
    PRX["$id"]=$rx
    PTX["$id"]=$tx
    PNAME["$id"]=$name
  done < "$PREV"

  : > "$OUT"
  while IFS=$'\t' read -r id name pid arx atx; do
    brx=${PRX[$id]:-0}
    btx=${PTX[$id]:-0}
    rx_rate=$((arx - brx))
    tx_rate=$((atx - btx))
    [ "$rx_rate" -lt 0 ] && rx_rate=0
    [ "$tx_rate" -lt 0 ] && tx_rate=0
    total=$((rx_rate + tx_rate))
    # total<TAB>name<TAB>rx_rate<TAB>tx_rate<TAB>total
    printf '%d\t%s\t%d\t%d\t%d\n' "$total" "$name" "$rx_rate" "$tx_rate" "$total" >> "$OUT"
  done < "$NOW"

  echo "==== $ts (rates over ${INTERVAL}s) ===="
  if [ -s "$OUT" ]; then
    sort -t $'\t' -nr -k1,1 "$OUT" | awk -F'\t' '{printf "%-28s RX:%8d B/s  TX:%8d B/s  TOT:%8d B/s\n", $2, $3, $4, $5}'
  else
    echo "No containers found."
  fi

  mv "$NOW" "$PREV"
  sleep "$INTERVAL"
done