Framework configuration and parsing

This section describes the src.cli, responsible for parsing input configuration.

CLI functionality

Overview

Flexibility and extensibility are among the MDTF project’s design goals, which must be accommodated by the package’s configuration logic. Our use case requires the following features:

• Allow for specifying and recording user input in a file, to allow provenance of package runs and to eliminate the need for long strings of CLI flags.

• Record whether the user has explicitly set an option (to a value which may or may not be the default), or whether the option is unset and its default value is being used.

• Enable site-specific customizations, which can add to or modify any of the above properties.

• Define CLIs through configuration files instead of code to streamline the process of defining all of the above.

The MDTF framework uses the Python Click package to create the CLI from the runtime configuration file options, eliminating the need for custom the CLI modules and plugins in prior versions of the code. Parameters specified in the runtime configuration file (e.g., templates/runtime_config.[jsonc | yml]) are passed to a click context object (ctx) by attaching the @click.option decorator to the -f parameter associated with the path to the runtime config file (e.g., ./mdtf -f [runtime_config_file]). The ctx object that is instantiated in the mdtf_framework.py driver contains the path to the runtime config file passed with the -f parameter. mdtf_framework.py then calls cli.py utilities to parse the runtime configuration file and pass the the runtime parameters to a config dictionary attribute attached to the ctx instance. The config information is then passed to other framework methods and classes.