Install a postgresql extension

    CLI Example:

    .. code-block:: bash

        salt '*' postgres.create_extension 'adminpack'

def create_extension(name,
                     if_not_exists=None,
                     schema=None,
                     ext_version=None,
                     from_version=None,
                     user=None,
                     host=None,
                     port=None,
                     maintenance_db=None,
                     password=None,
                     runas=None):
    '''
    Install a postgresql extension

    CLI Example:

    .. code-block:: bash

        salt '*' postgres.create_extension 'adminpack'

    '''
    if if_not_exists is None:
        if_not_exists = True
    mtdata = create_metadata(name,
                             ext_version=ext_version,
                             schema=schema,
                             user=user,
                             host=host,
                             port=port,
                             maintenance_db=maintenance_db,
                             password=password,
                             runas=runas)
    installed = _EXTENSION_NOT_INSTALLED not in mtdata
    installable = is_available_extension(name,
                                         user=user,
                                         host=host,
                                         port=port,
                                         maintenance_db=maintenance_db,
                                         password=password,
                                         runas=runas)
    if installable:
        if not installed:
            args = ['CREATE EXTENSION']
            if if_not_exists:
                args.append('IF NOT EXISTS')
            args.append('"{0}"'.format(name))
            sargs = []
            if schema:
                sargs.append('SCHEMA "{0}"'.format(schema))
            if ext_version:
                sargs.append('VERSION {0}'.format(ext_version))
            if from_version:
                sargs.append('FROM {0}'.format(from_version))
            if sargs:
                args.append('WITH')
                args.extend(sargs)
            args.append(';')
            cmd = ' '.join(args).strip()
        else:
            args = []
            if schema and _EXTENSION_TO_MOVE in mtdata:
                args.append('ALTER EXTENSION "{0}" SET SCHEMA "{1}";'.format(
                    name, schema))
            if ext_version and _EXTENSION_TO_UPGRADE in mtdata:
                args.append('ALTER EXTENSION "{0}" UPDATE TO {1};'.format(
                    name, ext_version))
            cmd = ' '.join(args).strip()
        if cmd:
            _psql_prepare_and_run(
                ['-c', cmd],
                runas=runas, host=host, user=user, port=port,
                maintenance_db=maintenance_db, password=password)
    mtdata = create_metadata(name,
                             ext_version=ext_version,
                             schema=schema,
                             user=user,
                             host=host,
                             port=port,
                             maintenance_db=maintenance_db,
                             password=password,
                             runas=runas)
    ret = True
    for i in _EXTENSION_FLAGS:
        if (i in mtdata) and (i != _EXTENSION_INSTALLED):
            ret = False
    if not ret:
        log.info('Failed to create ext: %s', name)
    return ret