Set up Postgres server, user and database with fabric. Put into fabfile.py

fabfile.py

def _run_as_pg(command):
    return sudo('sudo -u postgres %s' % command)

def pg_user_exists(username):
    with settings(hide('running', 'stdout', 'stderr', 'warnings'), warn_only=True):
        res = _run_as_pg('''psql -t -A -c "SELECT COUNT(*) FROM pg_user WHERE usename = '%(username)s';"''' % locals())
    return (res == "1")

def pg_database_exists(database):
    with settings(hide('running', 'stdout', 'stderr', 'warnings'), warn_only=True):
        res = _run_as_pg('''psql -t -A -c "SELECT COUNT(*) FROM pg_database WHERE datname = '%(database)s';"''' % locals())
    return (res == "1")

def pg_create_user(username, password):
    _run_as_pg('''psql -t -A -c "CREATE USER %(username)s WITH PASSWORD '%(password)s';"''' % locals())

def pg_create_database(database, owner):
    _run_as_pg('createdb %(database)s -O %(owner)s' % locals())


@task
def configure_postgres():
    if not pg_user_exists(env.pg_user):
        pg_create_user(env.pg_user, env.pg_password)
    if not pg_database_exists(env.pg_database):
        pg_create_database(env.pg_database, env.pg_user)