docker-postgres-backup/docker-entrypoint-initdb-co.../1.0.0_05_create_user.sh

#! /usr/bin/env bash

if [ "${POSTGRES_SLAVE_MODE}" == 1 ]
then
  echo "Database is in slave mode. Exiting."
  exit 0
fi

if [ "${POSTGRES_USER}" != 'postgres' ]
then
  psql <<-EOF
  CREATE USER "${POSTGRES_USER}" WITH SUPERUSER PASSWORD '${POSTGRES_PASSWORD}';
EOF
else
  psql <<-EOF
  ALTER USER "${POSTGRES_USER}" WITH SUPERUSER PASSWORD '${POSTGRES_PASSWORD}';
EOF
fi