From 1d1f9e84b0b92a8785964da3590356dc112f0a6f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Berm=C3=BChler?=
 <31950929+dbermuehler@users.noreply.github.com>
Date: Fri, 19 Aug 2022 19:54:52 +0200
Subject: [PATCH] Logging silenced if parsedmarc is used as Library (#344)

By default, libraries should not configure their logger to give the developer, who is using the library, the freedom to decide how log messages are logged. For this reason no handler other than the NullHandler or log level should be set by the library.

For more information about this topic see here: https://realpython.com/python-logging-source-code/#library-vs-application-logging-what-is-nullhandler
---
 parsedmarc/__init__.py    | 9 +--------
 parsedmarc/cli.py         | 8 +++++++-
 parsedmarc/elastic.py     | 5 +----
 parsedmarc/kafkaclient.py | 5 +----
 parsedmarc/log.py         | 4 ++++
 parsedmarc/mail/gmail.py  | 4 +---
 parsedmarc/mail/graph.py  | 5 +----
 parsedmarc/mail/imap.py   | 5 +----
 parsedmarc/s3.py          | 4 +---
 parsedmarc/splunk.py      | 4 +---
 parsedmarc/syslog.py      | 2 --
 parsedmarc/utils.py       | 2 +-
 12 files changed, 20 insertions(+), 37 deletions(-)
 create mode 100644 parsedmarc/log.py

diff --git a/parsedmarc/__init__.py b/parsedmarc/__init__.py
index ea40367..8a6800c 100644
--- a/parsedmarc/__init__.py
+++ b/parsedmarc/__init__.py
@@ -28,6 +28,7 @@ from expiringdict import ExpiringDict
 from lxml import etree
 from mailsuite.smtp import send_email
 
+from parsedmarc.log import logger
 from parsedmarc.mail import MailboxConnection
 from parsedmarc.utils import get_base_domain, get_ip_address_info
 from parsedmarc.utils import is_outlook_msg, convert_outlook_msg
@@ -36,14 +37,6 @@ from parsedmarc.utils import timestamp_to_human, human_timestamp_to_datetime
 
 __version__ = "8.3.0"
 
-formatter = logging.Formatter(
-    fmt='%(levelname)8s:%(filename)s:%(lineno)d:%(message)s',
-    datefmt='%Y-%m-%d:%H:%M:%S')
-handler = logging.StreamHandler()
-handler.setFormatter(formatter)
-
-logger = logging.getLogger("parsedmarc")
-logger.addHandler(handler)
 logger.debug("parsedmarc v{0}".format(__version__))
 
 feedback_report_regex = re.compile(r"^([\w\-]+): (.+)$", re.MULTILINE)
diff --git a/parsedmarc/cli.py b/parsedmarc/cli.py
index 2b6f17a..820b1e6 100644
--- a/parsedmarc/cli.py
+++ b/parsedmarc/cli.py
@@ -25,9 +25,15 @@ from parsedmarc import get_dmarc_reports_from_mailbox, watch_inbox, \
 from parsedmarc.mail import IMAPConnection, MSGraphConnection, GmailConnection
 from parsedmarc.mail.graph import AuthMethod
 
+from parsedmarc.log import logger
 from parsedmarc.utils import is_mbox
 
-logger = logging.getLogger("parsedmarc")
+formatter = logging.Formatter(
+    fmt='%(levelname)8s:%(filename)s:%(lineno)d:%(message)s',
+    datefmt='%Y-%m-%d:%H:%M:%S')
+handler = logging.StreamHandler()
+handler.setFormatter(formatter)
+logger.addHandler(handler)
 
 
 def _str_to_list(s):
diff --git a/parsedmarc/elastic.py b/parsedmarc/elastic.py
index ee18e71..80f9f09 100644
--- a/parsedmarc/elastic.py
+++ b/parsedmarc/elastic.py
@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 
-import logging
 from collections import OrderedDict
 
 from elasticsearch_dsl.search import Q
@@ -8,12 +7,10 @@ from elasticsearch_dsl import connections, Object, Document, Index, Nested, \
     InnerDoc, Integer, Text, Boolean, Ip, Date, Search
 from elasticsearch.helpers import reindex
 
-
+from parsedmarc.log import logger
 from parsedmarc.utils import human_timestamp_to_datetime
 from parsedmarc import InvalidForensicReport
 
-logger = logging.getLogger("parsedmarc")
-
 
 class ElasticsearchError(Exception):
     """Raised when an Elasticsearch error occurs"""
diff --git a/parsedmarc/kafkaclient.py b/parsedmarc/kafkaclient.py
index 6204631..779746a 100644
--- a/parsedmarc/kafkaclient.py
+++ b/parsedmarc/kafkaclient.py
@@ -1,6 +1,5 @@
 # -*- coding: utf-8 -*-
 
-import logging
 import json
 from ssl import create_default_context
 
@@ -10,9 +9,7 @@ from collections import OrderedDict
 from parsedmarc.utils import human_timestamp_to_datetime
 
 from parsedmarc import __version__
-
-logger = logging.getLogger("parsedmarc")
-
+from parsedmarc.log import logger
 
 class KafkaError(RuntimeError):
     """Raised when a Kafka error occurs"""
diff --git a/parsedmarc/log.py b/parsedmarc/log.py
new file mode 100644
index 0000000..c10988d
--- /dev/null
+++ b/parsedmarc/log.py
@@ -0,0 +1,4 @@
+import logging
+
+logger = logging.getLogger(__name__)
+logger.addHandler(logging.NullHandler())
diff --git a/parsedmarc/mail/gmail.py b/parsedmarc/mail/gmail.py
index 504d28a..58aed20 100644
--- a/parsedmarc/mail/gmail.py
+++ b/parsedmarc/mail/gmail.py
@@ -1,4 +1,3 @@
-import logging
 from base64 import urlsafe_b64decode
 from functools import lru_cache
 from pathlib import Path
@@ -11,10 +10,9 @@ from google_auth_oauthlib.flow import InstalledAppFlow
 from googleapiclient.discovery import build
 from googleapiclient.errors import HttpError
 
+from parsedmarc.log import logger
 from parsedmarc.mail.mailbox_connection import MailboxConnection
 
-logger = logging.getLogger("parsedmarc")
-
 
 def _get_creds(token_file, credentials_file, scopes, oauth2_port):
     creds = None
diff --git a/parsedmarc/mail/graph.py b/parsedmarc/mail/graph.py
index 09bbbfa..80b0895 100644
--- a/parsedmarc/mail/graph.py
+++ b/parsedmarc/mail/graph.py
@@ -1,4 +1,3 @@
-import logging
 from enum import Enum
 from functools import lru_cache
 from pathlib import Path
@@ -10,6 +9,7 @@ from azure.identity import UsernamePasswordCredential, \
     TokenCachePersistenceOptions, AuthenticationRecord
 from msgraph.core import GraphClient
 
+from parsedmarc.log import logger
 from parsedmarc.mail.mailbox_connection import MailboxConnection
 
 
@@ -19,9 +19,6 @@ class AuthMethod(Enum):
     ClientSecret = 3
 
 
-logger = logging.getLogger('parsedmarc')
-
-
 def _get_cache_args(token_path: Path):
     cache_args = {
         'cache_persistence_options':
diff --git a/parsedmarc/mail/imap.py b/parsedmarc/mail/imap.py
index 66ea2e6..8e7aba7 100644
--- a/parsedmarc/mail/imap.py
+++ b/parsedmarc/mail/imap.py
@@ -1,16 +1,13 @@
-import logging
 from time import sleep
 
 from imapclient.exceptions import IMAPClientError
 from mailsuite.imap import IMAPClient
 from socket import timeout
 
+from parsedmarc.log import logger
 from parsedmarc.mail.mailbox_connection import MailboxConnection
 
 
-logger = logging.getLogger("parsedmarc")
-
-
 class IMAPConnection(MailboxConnection):
     def __init__(self,
                  host=None,
diff --git a/parsedmarc/s3.py b/parsedmarc/s3.py
index 499952f..e8269ab 100644
--- a/parsedmarc/s3.py
+++ b/parsedmarc/s3.py
@@ -1,13 +1,11 @@
 # -*- coding: utf-8 -*-
 
-import logging
 import json
 import boto3
 
+from parsedmarc.log import logger
 from parsedmarc.utils import human_timestamp_to_datetime
 
-logger = logging.getLogger("parsedmarc")
-
 
 class S3Client(object):
     """A client for a Amazon S3"""
diff --git a/parsedmarc/splunk.py b/parsedmarc/splunk.py
index 1d40282..e479794 100644
--- a/parsedmarc/splunk.py
+++ b/parsedmarc/splunk.py
@@ -1,4 +1,3 @@
-import logging
 from urllib.parse import urlparse
 import socket
 import json
@@ -7,12 +6,11 @@ import urllib3
 import requests
 
 from parsedmarc import __version__
+from parsedmarc.log import logger
 from parsedmarc.utils import human_timestamp_to_timestamp
 
 urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
 
-logger = logging.getLogger("parsedmarc")
-
 
 class SplunkError(RuntimeError):
     """Raised when a Splunk API error occurs"""
diff --git a/parsedmarc/syslog.py b/parsedmarc/syslog.py
index fbdd136..44fca68 100644
--- a/parsedmarc/syslog.py
+++ b/parsedmarc/syslog.py
@@ -7,8 +7,6 @@ import json
 from parsedmarc import parsed_aggregate_reports_to_csv_rows,\
     parsed_forensic_reports_to_csv_rows
 
-logger = logging.getLogger("parsedmarc")
-
 
 class SyslogClient(object):
     """A client for Syslog"""
diff --git a/parsedmarc/utils.py b/parsedmarc/utils.py
index e111981..cfa6283 100644
--- a/parsedmarc/utils.py
+++ b/parsedmarc/utils.py
@@ -32,6 +32,7 @@ import geoip2.errors
 import requests
 import publicsuffix2
 
+from parsedmarc.log import logger
 import parsedmarc.resources
 
 USER_AGENT = "Mozilla/5.0 (({0} {1})) parsedmarc".format(
@@ -42,7 +43,6 @@ USER_AGENT = "Mozilla/5.0 (({0} {1})) parsedmarc".format(
 parenthesis_regex = re.compile(r'\s*\(.*\)\s*')
 
 null_file = open(os.devnull, "w")
-logger = logging.getLogger("parsedmarc")
 mailparser_logger = logging.getLogger("mailparser")
 mailparser_logger.setLevel(logging.CRITICAL)