Once thought of as a luxury, an automated deployment strategy is now largely considered a necessity as Sitecore expands in terms of complexity, dependencies and standardization of configuration. Having gone through the pain of manual deployments using build scripts, diff tools and carefully updating of configuration files, it’s easy to see the need for a reliable and repeatable deployment process. Don’t think this is a need across the Sitecore community? Attend any session at Sitecore Symposium or user group centered around this topic. Sitecore Symposium specifically had standing room only for talks on continuous deployment and delivery.
Recently, we upgraded Sitecore form 8.1 update 3 to 9.0 update 1. Note this post deals with an XM instance. XP upgrades may follow a similar path, however, XP specific upgrade tasks are not covered here.