Recuresively resolve Zabbix user macro within string

expand_macro.py

import re
import logging

def expand_macro(zapi, itemid, hostid, macro):
    """Expand macro in passed string, recursively. Non-existent macro resolved to empty string.

Example:
    # {$MACRO} resolves to "test macro in ${ENV} environment"
    # {$ENV} resolves to "dev"
    >>> print(expand_macro(zapi, 12345, 54321, "string with {$MACRO}"))
    "string with test macro with dev environment"

    Args:
    zapi (ZabbixAPI): https://github.com/gescheit/scripts/tree/master/zabbix
    itemid (str or int): itemid of the item to expand
    hostid (str or int): hostid of the item to expand
    macro (str): string to expand

    Returns:
    str: string with expanded macros in it
"""
    # no macro left in passed string, return it
    if '{$' not in macro:
        return macro
    # macro inside but not yet called
    if not re.match(r'^{\$.+?}$', macro):
        return re.sub('{\$.+?}', lambda x: expand_macro(zapi, itemid, hostid, x.group()), macro)
    # flow for case macro is the only thing we have in passed string - we need to extract it
    result = zapi.usermacro.get({'hostids': hostid, 'output': ['value'], 'filter': {'macro': macro}})
    # we found result and expanding it in case there are more macro inside
    if result:
        return re.sub('{\$.+?}', lambda x: expand_macro(zapi, itemid, hostid, x.group()), result[0]['value'])
    # we haven't found result and need to go deeper
    template_id = zapi.item.get({'itemids': itemid, 'output': ['templateid']})[0]['templateid']
    if template_id == 0:
        logging.error("Reached parent template for itemid %s on host %s and didn't found macro %s, replacing with empty string", itemid, hostid, macro)
        return ''
    template_host_id = zapi.item.get({'itemids': template_id, 'output': [], 'selectHosts': ['hostid']})[0]['hosts'][0]['hostid']
    return expand_macro(zapi, template_id, template_host_id, macro)