Support for multiple users and multiple databases

[wilmardo]

Currently I am using the upstream image and a replica with hot_standby=on.
I mount a shell script to /docker-entrypoint-initdb.d/ to create multiple users and multiple databases. These script read from an environment variable in the format <user>:<password>:<db1>,<db2>|<second_user>:<password>:<db2>

# Create user harbor with password pass when non existing then create databases registry and clair and grant access to harbor when databases are non existing.
# Then create user test with password pass when non existing and create test_db and grant access to test.
POSTGRES_MULTIPLE_DATABASES="harbor:pass:registry,clair,notary_server,notary_signer|test:pass:test_db"

#!/bin/bash

set -e
set -u

# Source for the create user logic:
# https://stackoverflow.com/a/49858797
function create_user() {
	local user=$1
	local password=$2
	echo "  Creating user '$user'"
	psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
    DO \$\$
    BEGIN
      CREATE USER $user WITH ENCRYPTED PASSWORD '$password';
      EXCEPTION WHEN OTHERS THEN
      RAISE NOTICE 'not creating role $user -- it already exists';
    END
    \$\$;
EOSQL
}

function create_database() {
	local database=$1
	local owner=$2
	echo "  Creating database '$database' and granting to '$owner'"
	psql -v ON_ERROR_STOP=1 --username "$POSTGRES_USER" <<-EOSQL
    DO \$\$
    BEGIN
      CREATE DATABASE $database;
      GRANT ALL PRIVILEGES ON DATABASE $database TO $owner;
      EXCEPTION WHEN OTHERS THEN
      RAISE NOTICE 'not creating and granting database $database -- it already exists';
    END
    \$\$;
EOSQL
}

function main() {
  if [ -n "$POSTGRES_MULTIPLE_DATABASES" ]; then
    echo "Multiple database creation requested: $POSTGRES_MULTIPLE_DATABASES"
    # Declare variables
    local user
    local password
    local db_list

    for entry in $(echo "$POSTGRES_MULTIPLE_DATABASES" | tr '|' ' '); do
      # Split user
      user=$(echo "$entry" | tr ':' ' ' | awk  '{print $1}')
      # Split password
      password=$(echo "$entry" | tr ':' ' ' | awk  '{print $2}')
      # Split access list
      db_list=$(echo "$entry" | tr ':' ' ' | awk  '{print $3}')

      create_user "$user" "$password"
      for db in $(echo "$db_list" | tr ',' ' '); do
        create_database "$db" "$user"
      done
    done
    echo "Multiple databases created"
  fi
}

main

Is this something you would like to be built in the Docker containers and made available within the Helm chart?

Suggestions for improvements are welcome to!