Backup Containerized Postgre Database to Docker Host

There’s a number of ways to backup a containerized PostgreSQL database to the Docker host. This is one way that has worked for us.

We use Docker Compose to startup our application stack, which includes a PostgreSQL instance.

First we add a volume to our docker-compose.yml file that is mapped to our host path:

volumes:
- <host path>:/etc/postgres.backups

Now the container has a volume mounted to /etc/postgres.backups

Within the host path we’ve placed our Bash script:

#!/bin/bash

backuppath=/etc/postgres.backups/
backupfile=postgres_backup_docker_id_$(hostname -f)_$(date +"%Y_%m_%d_%I_%M_%p").sql

echo "####"
echo " "

echo "Creating backup: $backuppath$backupfile"
# Backup a specific database
# pg_dump -U $POSTGRES_USER <database name> $backuppath$backupfile
# Backup all databases
pg_dumpall -U $POSTGRES_USER --verbose -f $backuppath$backupfile

echo "Compressing backup: $backuppath$backupfile.gz"
gzip $backuppath$backupfile

# Delete files older than 5 days
days=5
echo "Cleaning files older than $days days: $backuppath*.gz"
find /etc/postgres.backups/ -name "*.gz" -type f -mtime +$days -delete

echo "Finished backup"

echo " "
echo "####"

This script contains some additional goodies like backup compression and retention cleanup that can be omitted.

The $POSTGRES_USER environment variable is setup via an environment file configured in docker-compose.yml:

env_file:
     - .env.postgres.docker

The backup script can now be executed within the container from the host like so:

 docker exec -it <container name> bash /etc/postgres.backups/postgres.backup.sh

A new backup file will be created in the host path

The backup script can be scheduled on the host or executed on-demand.

Below is the full docker-compose.yml:

version: "3.0"

services:
  db:
    container_name: app-db
    image: postgres
    env_file:
      - .env.postgres.docker
    volumes:
      - pgdata:/var/lib/postgresql/data
      - <host path>:/etc/postgres.backups
    ports:
      - "5432:5432"
    restart: unless-stopped
    networks:
      - net-application
volumes:
  pgdata:
    external: false
networks:
  net-application: