Error: Postgres database import in docker container

Question

I'm running a ruby on rails application in docker container. I want to create and then restore the database dump in postgres container. But I'm

Below is what I've done so far:

1) Added bash script in /docker-entrypoint-initdb.d folder. Script is just to create database:

psql -U docker -d postgres -c 'create database dbname;'

RESULT: Database created but rails server exited with code 0. Error: web_1 exited with code 0

2) Added script to be executed before docker-compose up.

# Run docker db container
echo "Running db container"
docker-compose run -d db

# Sleep for 10 sec so that container have time to run
echo "Sleep for 10 sec"
sleep 10

echo 'Copying db_dump.gz to db container'
docker cp db_dump/db_dump.gz $(docker-compose ps -q db):/

# Create database `dbname`
echo 'Creating database `dbname`'
docker exec -i $(docker-compose ps -q db) psql -U docker -d postgres -c 'create database dbname;'

echo 'importing database `dbname`'
docker exec -i $(docker-compose ps -q db) bash -c "gunzip -c /db_dump.gz | psql -U postgres dbname"

RESULT: Database created and restored data. But another container runs while running web application server using docker-compose up.

docker--compose.yml:

version: '2'

services:

  db:
    image: postgres

    environment:
      - POSTGRES_PASSWORD=docker
      - POSTGRES_USER=docker

  web:
    build: .
    command: bundle exec rails s -p 3000 -b '0.0.0.0' -d
    image: uname/application
    links:
      - db
    ports:
      - "3000:3000"
    depends_on:
      - db
    tty: true

Can some one please help to create and import database?

EDIT:

I've tried one more approach by adding POSTGRES_DB=db_name environment variable in docker-compose.yml file so that database will be created and after running the application (docker-compose up), I'll import the database. But getting an error: web_1 exited with code 0.

I'm confused why I'm getting this error (in first and third approach), seems to be something is messed up in docker-compose file.

Answer 1

Set up a database dump mount

You'll need to mount the dump into the container so you can access it. Something like this in docker-compose.yml:

db:
  volumes:
    - './db_dump:/db_dump'

Make a local directory named db_dump and place your db_dump.gz file there.

Start the database container

Use POSTGRES_DB in the environment (as you mentioned in your question) to automatically create the database. Start db by itself, without the rails server.

docker-compose up -d db

Import data

Wait a few seconds for the database to be available. Then, import your data.

docker-compose exec db gunzip /db_dump/db_dump.gz
docker-compose exec db psql -U postgres -d dbname -f /db_dump/db_dump.gz
docker-compose exec db rm -f /db_dump/db_dump.gz

You can also just make a script to do this import, stick that in your image, and then use a single docker-compose command to call that. Or you can have your entrypoint script check whether a dump file is present, and if so, unzip it and import it... whatever you need to do.

Start the rails server

docker-compose up -d web

Automating this

If you are doing this by hand for prep of a new setup, then you're done. If you need to automate this into a toolchain, you can do some of this stuff in a script. Just start the containers separately, doing the db import in between, and use sleep to cover any startup delays.

Answer 2

web_1 exited with code 0

Did you tried check the log of web_1 container? docker-compose logs web

I strongly recommend you don't initialize your db container manually, make it automatically within the process of start container.

Look into the entrypoint of postgres, we could just put the db_dump.gz into /docker-entrypoint-initdb.d/ directory of the container, and it will be automatic execute, so docker-compose.yml could be:

db:
  volumes:
    - './initdb.d:/docker-entrypoint-initdb.d'

And put your db_dump.gz into ./initdb.d on your local machine.