Configuring and logging

Overview

Questions

• What are QMI configuration and log files?

Objectives

• Know how to create a basic configuration file.

QMI Configuration and log file

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Many aspects of QMI are configurable via a configuration file. The syntax of this file is very similar to JSON, but unlike JSON, the configuration file may contain comments starting with a # character. By default, QMI attempts to read the configuration from a file named qmi.conf in the home directory (i.e. ‘/home/’ in Linux or ‘C:<user_name>’ folder on Windows). If you want to use a different file name or location, you can specify the configuration file path either as the second argument of qmi.start() or in the environment variable QMI_CONFIG. Let’s create a configuration file qmi.conf at home directory with the following contents:

JSON

{
    # Log level for messages to the console.
    "logging": {
        "console_loglevel": "INFO"
    }
}

This configuration file changes the log level for messages that appear on your terminal. By default, QMI prints only warnings and error messages. Our new configuration also enables printing of informational messages. For further details about logging options, see documentation on qmi.core.logging_init module. Test the new configuration file in a new Python session:

PYTHON

import qmi
qmi.start("hello_world")
qmi.stop()

Notice that we do not pass a ‘None’ as the second argument to qmi.start(). As a result, QMI will try to read the configuration file from its default location. If the configuration file is found and written correctly, QMI should print a bunch of log messages after the call to qmi.start(). If your configuration file is not in the default location, you may have to specify its location with the config_file= argument to qmi.start(). At your home directory should also now be a file called qmi.log. The file works as a log for QMI programs. You will find in this file a log of actions you took until now while testing your first examples. The logging can be disabled by giving input parameter init_logging=False for qmi.start(). We will add more settings to the configuration file as we progress through this tutorial.

Key Points

• qmi.conf has a JSON-like structure
• Log levels are set within “logging” keyword section
• Default name and location of the log file are qmi.log and the user’s home directory