Matt Glaman Publishes Drupal Caching Guide on Leanpub

A new book by Drupal contributor Matt Glaman examines the platform’s caching architecture, bringing together its multiple layers into a single technical guide now available on Leanpub. The publication focuses on how caching operates across render pipelines, storage backends, HTTP responses, and reverse proxy systems.

The book, titled "Understanding Drupal: A Complete Guide to Caching Layers," is the result of a development process that began in early 2023 and resumed after a prolonged pause. Glaman completed the work following earlier delays linked to project commitments, including involvement in product development at Acquia.

The guide is structured to move from foundational concepts to implementation details. Early chapters explain cacheable metadata, including cache tags, contexts, and max-age, and how these elements propagate through Drupal’s render pipeline to determine cache behaviour.

Subsequent sections examine cache storage and backends, including database-backed systems and alternative configurations. The book also covers render caching and fragment caching, explaining how Drupal uses its render tree and Variation Cache to optimise partial page delivery.

Response-level caching is addressed through discussion of Dynamic Page Cache, Internal Page Cache, and streaming techniques such as BigPipe. These sections connect application-level caching with delivery mechanisms that affect both anonymous and authenticated users.

HTTP caching headers are analysed in detail, including Cache-Control, ETag, and Vary, with attention to how Drupal generates these headers based on cacheable metadata. The book also explains how reverse proxies and content delivery networks interact with Drupal’s caching system.

Later chapters focus on debugging and implementation practices. These include inspecting cache metadata, troubleshooting invalidation issues, and writing cacheable code that integrates correctly with Drupal’s APIs.

The book is positioned for a broad audience within the Drupal ecosystem, including site builders seeking to understand cache tags and developers working with Drupal 11 APIs. It emphasises practical examples and real-world debugging scenarios rather than abstract explanations.

The Leanpub release model allows iterative access to the material, with pricing set through a minimum and suggested range. The announcement and supporting material were published through Glaman’s blog and Leanpub listing.