SQLite WAL Mode Across Docker Containers Sharing a Volume

Simon Willison’s Weblog Subscribe Sponsored by: WorkOS — Production-ready APIs for auth and access control, so you can ship faster. RESEARCH SQLite WAL Mode Across Docker Containers Sharing a Volume — SQLite’s WAL mode reliably supports concurrent access when two Docker containers share a volume on the same host, due to shared kernel and filesystem semantics. The experiment, using Docker Desktop for macOS and a named volume, demonstrated real-time propagation of database changes and effective memory-mapped file sharing by monitoring `.db-shm`. Inspired by this conversation on Hacker News about whether two SQLite processes in separate Docker containers that share the same volume might run into problems due to WAL shared memory. The answer is that everything works fine - Docker containers on the same host and filesystem share the same shared memory in a way that allows WAL to collaborate as it should. Posted 7th April 2026 at 3:41 pm Recent articles Anthropic's Project Glasswing - restricting Claude Mythos to security researchers - sounds necessary to me - 7th April 2026 The Axios supply chain attack used individually targeted social engineering - 3rd April 2026 Highlights from my conversation about agentic engineering on Lenny's Podcast - 2nd April 2026 This is a beat by Simon Willison, posted on 7th April 2026. sqlite 457 docker 60 Monthly briefing Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments. Pay me to send you less! Sponsor & subscribe Disclosures Colophon © 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026