Backup MongoDB inside of Docker the easy way

Backing up a mongo instance is more confusing than it should be. Maybe you have run into a the input device is not a TTY or you simply don’t know how to do it? Here are two 1-Liner to backup and restore a running mongo instance.

Setup

First we define our mongo instance like below. Notice that instead of mapping the data directory onto our filesystem we have a native volume.

docker-compose.yml

version: '3.7'

volumes:
  db:

services:
  db:
    image: mongo:3-xenial
    restart: always
    volumes:
      - db:/data/db
    ports:
      - 27017:27017

Then start with docker-compose up -d.

Backup

First we will do a backup of our running instance.

docker-compose exec -T db mongodump --archive --gzip --db mydb > dump.gz

The -T option is for enabling piping the output to our own machine. We also tell mongo to use the --gzip option to compress the file significantly.
Lastly we specify the --db <database> that we want to backup.

Restore

Whenever we want to restore a db, or maybe seed it we can run the following:

docker-compose exec -T db mongorestore --archive --gzip < dump.gz