  Program repair research has made tremendous progress over the last few years,
and software development bots are now being invented to help developers gain
productivity. In this paper, we investigate the concept of a " program repair
bot " and present Repairnator. The Repairnator bot is an autonomous agent that
constantly monitors test failures, reproduces bugs, and runs program repair
tools against each reproduced bug. If a patch is found, Repairnator bot reports
it to the developers. At the time of writing, Repairnator uses three different
program repair systems and has been operating since February 2017. In total, it
has studied 11 317 test failures over 1 609 open-source software projects
hosted on GitHub, and has generated patches for 17 different bugs. Over months,
we hit a number of hard technical challenges and had to make various design and
engineering decisions. This gives us a unique experience in this area. In this
paper, we reflect upon Repairnator in order to share this knowledge with the
automatic program repair community.
