How do I create a database within a docker container using only the docker-compose file? - postgresql

Question

I'm trying to create a database and connect to it within my container network. I don't want to have to ssh into a box to create users/databases etc, as this is not a scalable or easily distributable process.
This is what I have so far:
# docker-compose.yml
db:
image: postgres:9.4
volumes:
- ./db/init.sql:/docker-entrypoint-initdb/10-init.sql
environment:
- PGDATA=/tmp
- PGDATABASE=web
- PGUSER=docker
- PGPASSWORD=password
This is my init.sql file:
CREATE DATABASE web;
CREATE USER docker WITH PASSWORD 'password';
GRANT ALL PRIVILEGES ON DATABASE web TO docker;
When I start up the container and try to connect to it, I get this error:
db_1 | FATAL: role "docker" does not exist
db_1 | done
db_1 | server started
db_1 | FATAL: database "web" does not exist
db_1 | psql: FATAL: database "web" does not exist
The first time this happened, I tried to create a role like this:
CREATE ROLE docker with SUPERUSER PASSWORD password;
GRANT web TO docker;
But it did not have any effect. To make matters even more confusing, when I use node-postgres to connect to the db, I get this error:
Error: connect ECONNREFUSED
But how can the connection be refused if the db service isnt even up??
In a nutshell, these are the questions I'm trying to solve:
How can I create a database using only the files in my project (i.e. no manual commands)?
How do I create a user/role using only the files in my project?
How do I connect to this database?
Thank you in advance.

Answer 1

How can I create a database using only the files in my project (i.e.
no manual commands)?
The minimal docker-compose.yml config for you defined user and database is:
postgres:
image: postgres:9.4
environment:
- POSTGRES_DB=web
- POSTGRES_USER=myuser
How do I create a user/role using only the files in my project?
To execute scripts on database initialization take a look at the official docs for initdb.
To get you started with a quick and dirty solution create a new file e.g. init_conf.sh in the same directory as your docker-compose.yml:
#!/bin/bash
set -e
psql -v ON_ERROR_STOP=1 -U "$POSTGRES_USER" -d "$POSTGRES_DB" <<-EOSQL
CREATE ROLE docker with SUPERUSER PASSWORD 'password';
EOSQL
And add the volumes directive to your docker-compose.yml.
volumes:
- .:/docker-entrypoint-initdb.d
Recreate your container because otherwise, you wouldn't trigger a new database initialization. That means, docker stop and docker rm the old one first before executing docker-compose up again. STDOUT gives you now some information about our newly introduced script.
How do I connect to this database?
To connect to your database with docker exec via the terminal:
docker exec -ti folder_postgres_1 psql -U myuser -d web
A docker-compose.yml in one of my production environments looks like the following:
services:
postgres:
logging: &logging
driver: json-file
options:
max-size: "10m"
max-file: "5"
build: ./docker/postgres # path to custom Dockerfile
volumes:
- postgres_data:/var/lib/postgresql/data
- postgres_backup:/backups
env_file: .env
restart: always
# ... other services like web, celery, redis, etc.
Dockerfile:
FROM postgres:latest
# ...
COPY *.sh /docker-entrypoint-initdb.d/
# ...

Answer 2

The environment variable you are using are wrong. Try this
version: '3.3'
services:
db:
image: postgres:9.4
restart: always
environment:
- POSTGRES_USER=docker
- POSTGRES_PASSWORD=password
- POSTGRES_DB=web
volumes:
- db_data:/var/lib/postgresql/data
# optional port
ports: ["5555:5432"]
volumes:
db_data:
then from any other docker-compose service you can access the DB at db:5432 and from your host machine you can access postgres on localhost:5555 if you also add the ports