A shell script to remove all exited docker containers that are older than a certain threshold. Customize the filter expression to restrict this to a certain group of containers. Should work on Linux and Mac OS.

cleanup-old-containers.sh

#!/bin/bash

FILTER="--filter label=myapp"
THRESHOLD=$((7 * 24 * 60 * 60))

NOW=$(date +%s)
USE_BSD_DATE=$(date -j >/dev/null 2>&1 && echo 1)

function date_to_timestamp {
  if [[ $USE_BSD_DATE ]]; then
    date -jf "%F %T %z" "$1" +%s
  else
    date --date="$date" +%s
  fi
}

docker ps -a $FILTER --format "{{.ID}} {{.CreatedAt}}" | sed 's/ CET$//' | while IFS= read -r line; do
  id=$(echo $line | sed 's/ .*$//')
  date=$(echo $line | sed 's/^[^ ]* //')
  timestamp=$(date_to_timestamp "$date")
  if [[ $((NOW - timestamp)) -gt THRESHOLD ]]; then 
    docker rm $id
  fi
done