hateful but sane mongo container backup cron

mongo_backup.sh

#!/bin/bash
containers=$(sudo docker ps | grep mongo | awk '{if(NR>1) print $NF}')
timestamp=$(date +%Y-%m-%d_%H-%M-%S)
backup_command="mongodump --gzip --archive=/data/db/$timestamp.tar.gz"
prune_command="find /data/db/ -type f -mtime +7 -name '*.gz' -execdir rm -- '{}' \;"
for container in $containers
do
  echo $container
  echo $backup_command
  docker exec $container /bin/sh -c "$backup_command"
  echo $prune_command
  docker exec $container /bin/sh -c "$prune_command"
done