Objectives 

This High Level Design Document describes the current LUTF design, code base, infrastructure requirements for its setup and the new features that can be added on top of the current design.

Reference Documents

Document Structure

This document is made up of the following sections:

Design Overview: Describes the existing infrastructure, code base and components of LUTF.

Setup and Usage: Describes how to setup and run LUTF on test nodes.

New Features: Describes the new features to be added to the current design.

LUTF Design Overview

The below diagram shows how LUTF interacts with LNet

Figure 1: System Level Diagram

LUTF Master-Agent

 The LUTF is designed with a Master-Agent approach to test LNet. The Master and Agent LUTF instance uses a telnet python module to communicate with each other and more than one Agent can communicate with single Master instance at the same time. The Master instance controls all the Agents connected to it. It controls the execution of the python test scripts to test LNet on Agent instances, collects the results of all the tests run on Agents and write them to a YAML file. It also controls the synchronization mechanism between test-scripts running on different Agents.

Components of LUTF

The LUTF is composed of two components:

1. C back-end infrastructure
   This allows for the setup of the TCP communication between the Master and Agent nodes (lutf.c). 
   
   Master mode: 
     Starts a listener thread to listen to Agent connections (lutf_listener.c).
     It maintains a list of all the Agents
     In Master mode: provides a library which is SWIG wrapped and callable from python scripts (liblutf_agent.c).
     In Master mode and Agent mode: start up a python interpreter. In agent mode the interpreter is only available through telnet (lutf_python.c).
   
   Agent mode: 
   A thread is started to maintain a heart beat with the master. The master uses the Heart beat to determine the aliveness of the agents.
   
   
   
2. Python Test infrastructure
   
   1. Provides a telnet server and client for Master<->Agent communication.
   2. Provides an Object Oriented infrastructure which facilitates running python tests scripts on the Agents and collecting results.
   3. Provides a mechanism to query IP addresses and the network interfaces on the Agents. This information can further be fetched by the test scripts on demand using an API.

SWIG & DLC Library

SWIG is used to wrap the DLC library and make it callable from Python. This allows Python test scripts to call DLC APIs directly to test LNet.