checking value on json

[buran]

not tested but try:

server_type = "server_type2"
 
try:
    data_config = json.load(json_file)
except ValueError:
    logging.critical("Data were not valid json for %s", data_config)
else:
    if server_type not in data_config['server_model'].keys():
        logging.critical("We can not continue: Server type %s not present in config file", server_type)

depending on what you would do further it may be better to try to access data you want with data_config['server_model'].get(server_type) and act accordingly from there