Backup/Restore a dockerized PostgreSQL database

Question

I'm trying to backup/restore a PostgreSQL database as is explained on the Docker website, but the data is not restored.

The volumes used by the database image are:

VOLUME  ["/etc/postgresql", "/var/log/postgresql", "/var/lib/postgresql"]

and the CMD is:

CMD ["/usr/lib/postgresql/9.3/bin/postgres", "-D", "/var/lib/postgresql/9.3/main", "-c", "config_file=/etc/postgresql/9.3/main/postgresql.conf"]

I create the DB container with this command:

docker run -it --name "$DB_CONTAINER_NAME" -d "$DB_IMAGE_NAME"

Then I connect another container to insert some data manually:

docker run -it --rm --link "$DB_CONTAINER_NAME":db "$DB_IMAGE_NAME" sh -c 'exec bash'
psql -d test -h $DB_PORT_5432_TCP_ADDR
# insert some data in the db
<CTRL-D>
<CTRL-D>

The tar archive is then created:

$ sudo docker run --volumes-from "$DB_CONTAINER_NAME" --rm -v $(pwd):/backup ubuntu tar cvf /backup/backup.tar /etc/postgresql /var/log/postgresql /var/lib/postgresql

Now I remove the container used for the db and create another one, with the same name, and try to restore the data inserted before:

$ sudo docker run --volumes-from "$DB_CONTAINER_NAME" --rm -v $(pwd):/backup ubuntu tar xvf /backup/backup.tar 

But the tables are empty, why is the data not properly restored ?

Answer 1

Backup your databases

docker exec -t your-db-container pg_dumpall -c -U postgres > dump_`date +%d-%m-%Y"_"%H_%M_%S`.sql

Restore your databases

cat your_dump.sql | docker exec -i your-db-container psql -U postgres