postgres-init.sh

#!/usr/bin/env bash
set -e

# This script runs only on first DB initialization (empty data volume).
# It creates an application database and user using env vars.

psql \
  -v ON_ERROR_STOP=1 \
  --username "$POSTGRES_USER" \
  --dbname "postgres" \
  --set=app_db_name="$APP_DB_NAME" \
  --set=app_db_user="$APP_DB_USER" \
  --set=app_db_password="$APP_DB_PASSWORD" \
  <<-'EOSQL'
  SELECT format(
    'CREATE ROLE %I LOGIN PASSWORD %L',
    :'app_db_user',
    :'app_db_password'
  )
  WHERE NOT EXISTS (
    SELECT 1 FROM pg_roles WHERE rolname = :'app_db_user'
  )
  \gexec

  SELECT format(
    'CREATE DATABASE %I OWNER %I',
    :'app_db_name',
    :'app_db_user'
  )
  WHERE NOT EXISTS (
    SELECT 1 FROM pg_database WHERE datname = :'app_db_name'
  )
  \gexec

  SELECT format(
    'GRANT ALL PRIVILEGES ON DATABASE %I TO %I',
    :'app_db_name',
    :'app_db_user'
  )
  \gexec
EOSQL