Developer Guide

Clone the pylog git repository

git clone ""

Mapped Diagnostics Context

The MDCs are logger instance specific key-value pairs, which are included to all log entries written via the logger instance.

By default, the library implements a root logger instance. MDCs added to the root logger instance are added only to the log entries written via the root logger instance.

Log entry format

Each log entry written with mdclog_write() function contains

  • Timestamp

  • Logger identity

  • Log entry severity

  • All existing MDC pairs

  • Log message text

Currently the library only supports JSON formatted output written to standard out of the process.

Example log output

{“ts”: 1603103945651, “crit”: “ERROR”, “id”: “”, “mdc”: {“PID”:101,”SYSTEM_NAME”: “Cloud-Space”, “HOST_NAME”: “master”, “SERVICE_NAME”: “TestApp”, “CONTAINER_NAME”: “Container-101”, “POD_NAME”: “POD-101”}, “msg”: “Hello World!”}


Install from PyPi

python3 -m pip install mdclogpy

Install using the source

python3 install


The library can be used in two ways shown below.

  1. Use the root logger

  import mdclogpy
  mdclogpy.error("This is an error log")
  1. Create a logger instance

  from mdclogpy import Logger
  my_logger = Logger()
  my_logger.error("This is an error log")

A program can create several logger instances.

mdclog_format_init() Adds the MDC log format with HostName, PodName, ContainerName, ServiceName,PID,CallbackNotifyforLogFieldChange

Pass configmap_monitor = False in mdclog_format_init() function to stop dynamic log level change based on configmap.

Logging Levels

"""Severity levels of the log messages."""
    DEBUG = 10
    INFO = 20
    WARNING = 30
    ERROR = 40

Pylog API’s

  1. Set current logging level

def set_level(self, level: Level):

       Keyword arguments:
       level -- logging level. Log messages with lower severity will be filtered.
  1. Return the current logging level

def get_level(self) -> Level:
  1. Add a logger specific MDC

def add_mdc(self, key: str, value: Value):

       Keyword arguments:
       key -- MDC key
       value -- MDC value
  1. Return logger’s MDC value with the given key or None

def get_mdc(self, key: str) -> Value:
  1. Remove logger’s MDC with the given key

def remove_mdc(self, key: str):
  1. Remove all MDCs of the logger instance.

def clean_mdc(self):
  1. Initialise Logging format:

This api Initialzes mdclog print format using MDC Dictionary by extracting the environment variables in the calling process for “SYSTEM_NAME”, “HOST_NAME”, “SERVICE_NAME”, “CONTAINER_NAME”, “POD_NAME” & “CONFIG_MAP_NAME” mapped to HostName, ServiceName, ContainerName, Podname and Configuration-file-name of the services respectively.

def mdclog_format_init(configmap_monitor=False):

       Keyword arguments:
       configmap_monitor -- Enables/Disables Dynamic log level change based on configmap
                         -- Boolean values True/False can be passed as per requirement.


Copyright (c) 2019 AT&T Intellectual Property. Copyright (c) 2018-2019 Nokia.

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

This source code is part of the near-RT RIC (RAN Intelligent Controller) platform project (RICP).

Unit testing

To run the unit tests run the following command in the package directory

python3 -m unittest discover