Do You Really Know How to Configure Your Software? Configuration Constraints in Source Code May Help

Misconfigurations have become one of the major causes of software failures because of their increasing prevalence and severity. The complexity of configurations and users' lack of domain knowledge are the main reasons for massive misconfigurations. Users usually identify and diagnose misconfigurations by making a comparison against the conditions that configuration options should satisfy, which we refer to as configuration constraints; however, sometimes it is hard for users to accomplish this work. Some work has been done on obtaining configuration constraints, especially from source code; nevertheless, only part of the situation has been considered, such as if-statement code snippets, limiting its help in misconfiguration diagnosis. In order to better extract configuration constraints for users' guidance and misconfiguration diagnosis, we carried out a comprehensive manual study on the existence and variance of the configuration constraints in the source code of five different pieces of widely used open-source software. Three categories of findings are summarized based on our study, namely the general statistics, the general features of specific kinds of constraints, and the obstacles to the automatic extraction of configuration constraints. With these findings, we proposed several suggestions to maximize the automatic extraction of configuration constraints. The results show that our suggestions could improve the extraction of configuration constraints compared to existing methods.