Configure postgres in a dockerfile [duplicate] - postgresql

Question

This question already has answers here:
How to create User/Database in script for Docker Postgres
(9 answers)
Closed 6 months ago.
I'm feeling a bit stupid, but...
All I want is a dockerfile that allows me to configure the db and the user to replace a script like
docker run --name $CONTAINER_NAME \
-p 5432:5432 \
-e POSTGRES_PASSWORD=mypass \
-e POSTGRES_DB=mydb \
-d postgres:13.5-alpine
###
### artificial wait here
###
docker exec $CONTAINER_NAME bash -c "psql --username postgres --command \"CREATE USER foo WITH SUPERUSER ENCRYPTED PASSWORD 'bar';\""
I.e. something like this (I thought):
FROM postgres:13.5-alpine
EXPOSE 5432
ENV POSTGRES_DB mydb
ENV POSTGRES_PASSWORD mypass
CMD psql --username postgres --command "CREATE USER foo WITH SUPERUSER ENCRYPTED PASSWORD 'bar';"
except this results in
psql: error: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
So what's the proper way to do this?

Answer 1

The Dockerfile is for building the image and the CMD will run when the container is ran. So the reason that
docker run --name $CONTAINER_NAME \
-p 5432:5432 \
-e POSTGRES_PASSWORD=mypass \
-e POSTGRES_DB=mydb \
-d postgres:13.5-alpine
###
### artificial wait here
###
docker exec $CONTAINER_NAME bash -c "psql --username postgres --command \"CREATE USER foo WITH SUPERUSER ENCRYPTED PASSWORD 'bar';\""
this worked is because the container (db) already is up and running before you input the SQL query into it. But if you try to do it from the Dockerfile it literally will try to run the psql command before the db is up and running, hence the connection error.
Your best bet is to use Docker Compose and add an initialize script
version: 3
services:
db:
image: postgres:13.5-alpine
environment:
POSTGRES_PASSWORD:mypass
POSTGRESS_DB: mydb
volume:
data:/var/lib/postgresql/data
volumes:
data:
Something like this(Excuse some typos. I'm typing from memory here.
See https://hub.docker.com/_/postgres for more info on initialising scripts
But it's basically a bash script you can write and then pass to docker compose to run upon container startup.