How to build a docker image which can restore databases whenever a new container is created from it

1. Run a postgres container.
docker container run --name <name> --detach -p 5432:5432 -e POSTGRES_PASSWORD=<my-pass> postgres
(ex: docker container run --name store --detach -p 5432:5432 -e POSTGRES_PASSWORD=my-pass postgres)

2. Create a directory in container to copy backup file.
docker exec <container_name> mkdir /<dir_name>
(ex: docker exec store mkdir /data)

3. Copy a backup file in container from Host or from another container.
docker cp /path/of/backup_file/database_bkp.sql <container_name>:/path/to/copy/file
(ex: docker cp /volume1/database_bkp.sql store:/data)

4. Install an editor in container (nano or vim etc...).
apt-get update
apt-get install vim
export EDITOR=vim


5. Create file in /docker-entrypoint-initdb.d directory
touch /docker-entrypoint-initdb.d/<file_name>
(ex: touch /docker-entrypoint-initdb.d/restore_db.sh )

6. write restore script in restore_db.sh

#!/bin/bash
set -e
psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" -f /data/database_bkp.sql

(if you dumped only a single database using pg_dump then please mention database name also in script)

psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" -d <database-name> -f /data/database_bkp.sql)

7. Make file executable
chmod 755 /docker-entrypoint-initdb.d/restore_db.sh

8. Build a new image from running container.
docker commit <running-container> <new-image>
(ex: docker commit store store_new)

9. Verify that image has built properly.
docker image ls

10. Run container from newly build image on a different port.
docker container run --name <name> --detach -p 4432:5432 -e POSTGRES_PASSWORD=<my-pass> <new-image>
(eg: docker container run --name store_postgres --detach -p 4432:5432 -e POSTGRES_PASSWORD=my-pass store_new)

This image has a restore file in it, a database is created when a new container is created from this image

Thanks for reading! 😊, This is my first post. Please let me know if you have any issue and also please write feedback.