David Farley co-authored continuous-delivery-book (2010) with jez-humble, the foundational text that codified continuous-delivery as a discipline and introduced the deployment-pipeline as its organizing technical concept.
Farley is a software developer and consultant — his background is on the development side of the dev-ops boundary, in contrast to many DevOps figures who came from operations. This development perspective shaped the book's treatment of the deployment pipeline: it is conceived as an extension of continuous integration (a development practice) into the deployment and operations domain. The pipeline is how developers' code changes become production software — a continuous, automated flow that the developer can understand and reason about.
continuous-delivery-book drew on Farley and Humble's work at ThoughtWorks, where they developed these practices on real projects. The book's contribution was systematization: it took emerging practices — automated testing, deployment automation, configuration management, continuous integration — and organized them into a coherent discipline with a defined vocabulary and a clear conceptual center (the deployment pipeline). The deployment pipeline concept in particular — the idea that every code change should flow through a defined sequence of automated verification stages — became the organizing metaphor for CD practice.
The book's publication in 2010 gave the continuous delivery community a shared text to reference and build on. It preceded the DevOps Handbook by six years and, along with the Velocity 2009 talks, was one of the movement's earliest systematic references.
Farley currently runs a YouTube channel focused on continuous delivery, software engineering, and software design, reaching a new generation of practitioners through that medium. The channel has a significant following (approximate — the specific subscriber count is not verified), making him an active voice in contemporary software engineering discussion rather than a purely historical figure.
His intellectual influences run through the Agile and XP communities (ThoughtWorks was a major XP practitioner), the continuous integration work of Kent Beck and the XP community, and the build and release engineering practices that were developing in the web operations world. Continuous delivery is, in one reading, XP's continuous integration extended all the way to production — Farley's background made that extension natural.