Issue 39142: logging.config.dictConfig will convert namedtuple to ConvertingTuple

While passing

{
    "version": 1,
    "disable_existing_loggers": False,
    "formatters": {
        "verbose": {"format": "%(levelname)s %(asctime)s %(module)s %(message)s"}
    },
    "handlers": {
        "stackdriver": {
            "class": "google.cloud.logging.handlers.CloudLoggingHandler",
            "client": client,
            "resource": resource,
        },
    },
    "root": {"level": "INFO", "handlers": ["stackdriver"]},
}

to logging.config.dictConfig it will convert resource, which is a namedtuple to ConvertingTuple, this will make google.cloud.logging.handlers.CloudLoggingHandler break down the line.

I am having to create a wrapper class like 

class Bla:
    resource = logging.resource.Resource(
        type="cloud_run_revision",
        labels={},
    )

    def _to_dict(self):
        return self.resource._to_dict()

to go around this

Thanks for the report. Can you please attach a sample script with the handler used to illustrate the issue?

Sorry for not sending a proper reproducible script when submitting the issue. End of the day and quite frustrated with the bug, anyway, I attached a full script that will show the error.

This is the custom handler I used:

class MyHandler(logging.StreamHandler):
    def __init__(self, resource, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.resource: namedtuple = resource
    
    def emit(self, record):
        record.msg += f" {self.resource.type}"
        return super().emit(record)


self.resource.type will throw and AttributeError when logging, because resource gets converted from a namedtuple to a ConvertingTuple.

Thanks for the details. Attached is a complete script. Looking at the source code, anything that looks like a tuple is converted into a tuple. namedtuple produces factory function that itself is a subclass of tuple. It led me to this interesting issue over detecting if it's a namedtuple issue7796 where detecting _fields in msg134186 is described as a workaround. So logging might detect namedtuple and skip conversion to ConvertingTuple using the workaround but it appears more of the class of special casing it here in logging  that will depend on namedtuple internals. There are no test failures. I will leave it to vinay on this.

>>> import collections
>>> person = collections.namedtuple('Person', 'age')
>>> isinstance(person(age=20), tuple)
True
>>> print(person._source) # works on 3.6 but verbose and _source were removed in 3.7 with 8b57d7363916869357848e666d03fa7614c47897
from builtins import property as _property, tuple as _tuple
from operator import itemgetter as _itemgetter
from collections import OrderedDict

class Person(tuple):
    'Person(age,)'
// snip more source code for person

# Detect namedtuple by checking for _fields attribute

diff --git a/Lib/logging/config.py b/Lib/logging/config.py
index 4a3b8966ed..ba6937e725 100644
--- a/Lib/logging/config.py
+++ b/Lib/logging/config.py
@@ -448,7 +448,8 @@ class BaseConfigurator(object):
             value = ConvertingList(value)
             value.configurator = self
         elif not isinstance(value, ConvertingTuple) and\
-                 isinstance(value, tuple):
+                 isinstance(value, tuple) and\
+                 not hasattr(value, '_fields'):
             value = ConvertingTuple(value)
             value.configurator = self
         elif isinstance(value, str): # str for py3k

New changeset 46abfc1416ff8e450999611ef8f231ff871ab133 by Vinay Sajip in branch 'master':
bpo-39142: Avoid converting namedtuple instances to ConvertingTuple. (GH-17773)
https://github.com/python/cpython/commit/46abfc1416ff8e450999611ef8f231ff871ab133

New changeset 1d5a7e5694bd9104f56f4f28357c2d13afd58a29 by Vinay Sajip (Miss Islington (bot)) in branch '3.8':
bpo-39142: Avoid converting namedtuple instances to ConvertingTuple. (GH-17773) (GH-17785)
https://github.com/python/cpython/commit/1d5a7e5694bd9104f56f4f28357c2d13afd58a29

New changeset 0e0e4acaabdcf8efb60cf75f08301022ac4422a4 by Vinay Sajip (Miss Islington (bot)) in branch '3.7':
bpo-39142: Avoid converting namedtuple instances to ConvertingTuple. (GH-17773) (GH-17786)
https://github.com/python/cpython/commit/0e0e4acaabdcf8efb60cf75f08301022ac4422a4

messages: + msg358948