This document describes Luca Milanesio's presentation on zero downtime upgrades for Gerrit. It discusses the different types of upgrades for Gerrit, including code-only, code and database schema, and code, database schema, and repository upgrades. It then outlines an 8 stage process for performing zero downtime upgrades of Gerrit using HAProxy load balancing to minimize downtime and ensure high availability, redirecting traffic from the old to new upgraded version.