this simple script searches all docker container and do a full db backup of all databases

full-db-backup.sh

#!/bin/bash
mysqlContainer=$(docker ps | grep 'mysql\|maria' | awk {'print $NF'}) #gets every container with a name containing mysql/mariadb
postgreContainer=$(docker ps | grep -Ei 'postgre'| grep -Eiv 'gitlab' | awk {'print $NF'}) #gets every container with a name containing postgre
gitlabPotsgreContainer=$(docker ps | grep -Ei 'postgre'| grep -Ei 'gitlab' | awk {'print $NF'}) #special gitlab because it use other env variables
timestamp=$(date +%Y-%m-%d_%H-%M-%S)

for container in $mysqlContainer; do
  containerStringParts=$(echo $container | tr "." "\n")
  for single in $containerStringParts; do
    simpleName=$single
    break 1
  done
  docker exec $container sh -c 'exec mysqldump "$MYSQL_DATABASE" -u"$MYSQL_USER" -p"$MYSQL_PASSWORD" -y' >/root/backups/db/$simpleName-$timestamp.sql
done

for container in $postgreContainer; do
  containerStringParts=$(echo $container | tr "." "\n")
  for single in $containerStringParts; do
    simpleName=$single
    break 1
  done
  docker exec $container sh -c 'pg_dump --dbname=postgresql://"$POSTGRES_USER":"$POSTGRES_PASSWORD"@localhost/"$POSTGRES_DB"' > /root/backups/db/$simpleName-$timestamp.sql
done

for container in $gitlabPotsgreContainer; do
  containerStringParts=$(echo $container | tr "." "\n")
  for single in $containerStringParts; do
    simpleName=$single
    break 1
  done
  docker exec $container sh -c 'pg_dump --dbname=postgresql://"$DB_USER":"$DB_PASS"@localhost/"$DB_NAME"' > /root/backups/db/$simpleName-$timestamp.sql
done