warden_server.py

    # Functions for validation and conversion of config values
    def facility(name):
        return int(getattr(logging.handlers.SysLogHandler, "LOG_" + name.upper()))

    def loglevel(name):
        return int(getattr(logging, name.upper()))

    def natural(name):
        num = int(name)
        if num<1:
            raise ValueError("Not a natural number")
        return num

    def filepath(name):
        # Make paths relative to dir of this script
        return path.join(path.dirname(__file__), name)

    def objdef(name):
        return objects[name.lower()]

    obj = objdef    # Draw into local namespace for init_obj

    objects = {}    # Already initialized objects

    # List of sections and objects, configured by them
    # First object in each object list is the default one, otherwise
    # "type" keyword in section may be used to choose other
    section_def = {
        "log": ["FileLogger", "SysLogger"],
        "db": ["MySQL"],
        "auth": ["X509Authenticator", "NoAuthenticator"],
        "validator": ["JSONSchemaValidator", "NoValidator"],
        "handler": ["WardenHandler"],
        "server": ["Server"]
    }

    # Object parameter conversions and defaults
    param_def = {
        "FileLogger": {
            "req": {"type": obj, "default": "req"},
            "filename": {"type": filepath, "default": path.join(path.dirname(__file__), path.splitext(path.split(__file__)[1])[0] + ".log")},
            "level": {"type": loglevel, "default": "info"},
        },
        "SysLogger": {
            "req": {"type": obj, "default": "req"},
            "socket": {"type": filepath, "default": "/dev/log"},
            "facility": {"type": facility, "default": "daemon"},
            "level": {"type": loglevel, "default": "info"}
        },
        "NoAuthenticator": {
            "req": {"type": obj, "default": "req"}
        },
        "X509Authenticator": {
            "req": {"type": obj, "default": "req"},
            "db": {"type": obj, "default": "db"}
        },
        "NoValidator": {
            "req": {"type": obj, "default": "req"},
        },
        "JSONSchemaValidator": {
            "req": {"type": obj, "default": "req"},
            "filename": {"type": filepath, "default": path.join(path.dirname(__file__), "idea.schema")}
        },
        "MySQL": {
            "req": {"type": obj, "default": "req"},
            "host": {"type": str, "default": "localhost"},
            "user": {"type": str, "default": "warden"},
            "password": {"type": str, "default": ""},
            "dbname": {"type": str, "default": "warden3"},
            "port": {"type": natural, "default": 3306},
            "retry_pause": {"type": natural, "default": 5},
            "retry_count": {"type": natural, "default": 3},
            "catmap_filename": {"type": filepath, "default": path.join(path.dirname(__file__), "catmap_mysql.json")},
            "tagmap_filename": {"type": filepath, "default": path.join(path.dirname(__file__), "tagmap_mysql.json")}
        },
        "WardenHandler": {
            "req": {"type": obj, "default": "req"},
            "validator": {"type": obj, "default": "validator"},
            "db": {"type": obj, "default": "DB"},
            "auth": {"type": obj, "default": "auth"},
            "send_events_limit": {"type": natural, "default": 10000},
            "get_events_limit": {"type": natural, "default": 10000},
            "description": {"type": str, "default": ""}
        },
        "Server": {
            "req": {"type": obj, "default": "req"},
            "auth": {"type": obj, "default": "auth"},
            "handler": {"type": obj, "default": "handler"}
        }
    }

    def init_obj(sect_name):
        config = conf.get(sect_name, {})
        sect_name = sect_name.lower()
        sect_def = section_def[sect_name]

        try:    # Object type defined?
            objtype = config["type"]
            del config["type"]
        except KeyError:    # No, fetch default object type for this section
            objtype = sect_def[0]
        else:
            if not objtype in sect_def:
                raise KeyError("Unknown type %s in section %s" % (objtype, sect_name))

        params = param_def[objtype]

        # No surplus parameters? Disallow also 'obj' attributes, these are only
        # to provide default referenced section
        for name in config:
            if name not in params or (name in params and params[name]["type"] is objdef):
                raise KeyError("Unknown key %s in section %s" % (name, sect_name))

        # Process parameters
        kwargs = {}
        for name, definition in params.iteritems():
            raw_val = config.get(name, definition["default"])
            try:
                val = definition["type"](raw_val)
            except Exception:
                raise KeyError("Bad value \"%s\" for %s in section %s" % (raw_val, name, sect_name))
            kwargs[name] = val

        cls = globals()[objtype]   # get class/function type
        try:
            obj = cls(**kwargs)         # run it
        except Exception as e:
            raise KeyError("Cannot initialize %s from section %s: %s" % (
                objtype, sect_name, str(e)))

        if isinstance(obj, Object):
            # Log only objects here, functions must take care of themselves
            logging.info("Initialized %s" % str(obj))

        objects[sect_name] = obj
        return obj

    # Init logging with at least simple stderr StreamLogger
    # Dunno if it's ok within wsgi, but we have no other choice, let's
    # hope it at least ends up in webserver error log
    StreamLogger()

    # Shared container for common data of ongoing WSGI request
    objects["req"] = Request()

    try:
        # Now try to init required objects
        for o in ("log", "db", "auth", "validator", "handler", "server"):
            init_obj(o)
    except Exception as e:
        logging.critical(str(e))
        logging.debug("", exc_info=sys.exc_info())
        return fallback_wsgi

    logging.info("Ready to serve")

    return objects["server"]


if __name__=="__main__":
    # FIXME: just development stuff
    srv = build_server(read_ini("warden3.cfg.wheezy-warden3"))