Distributed Systems Foundations

Distributed Systems Foundations covers: DDIA, Understanding Distributed Systems, Designing Distributed Systems. Understand the fundamental principles of distributed computing: CAP theorem, consistency models, replication, partitioning, consensus algorithms, and the failure modes that make distributed systems fundamentally different from single-machine systems. Your Rails app is already a distributed system — you just do not call it that. PostgreSQL replication is leader-based replication (DDIA Ch 5). Redis cluster is partitioning (DDIA Ch 6). Database transactions are ACID guarantees (DDIA Ch 7). Sidekiq is asynchronous message processing (DDIA Ch 11). After this module, you will understand why your Sidekiq job sometimes processes the same task twice (at-least-once delivery), why your read replica returns stale data (replication lag), and why your transaction sometimes deadlocks (serialization conflicts). These are not Rails bugs — they are distributed systems fundamentals. Cross-reference: This module overlaps with the Ruby/Rails path Module 10 and the CS path Quarters 9-10. DDIA is the shared spine. Read it once here; the other curricula reference the same concepts with different focus areas.

reading · we frame, you read MIT or the canonical taught · we author, no canonical fits ↺ spirals back to earlier lessons

Course locked

Complete Application Architecture Patterns first.

This course unlocks once you've finished its prerequisite. Open prerequisite →

reflection reading · 8 min

Honest Take — Before You Begin

Companion to SOFTWAREARCHITECTUREMASTERYCURRICULUM.md Honest reflections, no sugar coating.

preview →

reading · 30 min + ~550 min canonical L1

DDIA: The Book That Rewires How You Think About Data

Here's a bug you have probably shipped: a user updates their profile, the app redirects to the profile page, and the old data is still there. You added a sleep(0.1), or forced the…

primary Martin Kleppmann's Cambridge lectures

after L1 locked

reading · 30 min + ~550 min canonical L1

Understanding Distributed Systems: The Operational Playbook

At 2 a.m., nobody has ever been paged because a system violated linearizability. You get paged because checkout is timing out — and the cause is a third-party API that started ans…

primary Martin Kleppmann's Cambridge lectures

after L2 locked

reading · 30 min + ~550 min canonical L1

Designing Distributed Systems: Patterns You Can Point To

In Course 3 you learned that "Strategy" and "Adapter" compress a page of explanation into a word. Then you hit modern infrastructure diagrams — a proxy container glued next to eve…

primary Martin Kleppmann's Cambridge lectures

after L3 locked

exercise reading · 30 min L1

Module Checklist

Work through each item before the checkpoint.

after L4 locked

project reading · 150 min L1

Project: Design a Replication Strategy

Design how a real application replicates its data — single-leader, multi-leader, or leaderless — and justify the choice against the CAP theorem, the app's consistency requirements…

after L5 locked

6 lessons. Read in order; spiral back when you need to. By the end you'll have used the core ideas twice — once on the abstract, once on something you'll meet at work next week.