I Built Kafka From Scratch to Understand how it actually works
But Why?? I had used Kafka enough to know the terminology: topics, partitions, producers, consumers, replication. But knowing the pieces is different from understanding why they fit together the way they do. So I decided to build a lightweight Kafka-like message broker from scratch. Not as a replacement for Kafka, but as a way to understand what actually happens underneath the abstractions. Why…
The article discusses the author's decision to build a lightweight Kafka-like message broker named "kafka-lite" from scratch to gain a deeper understanding of how Kafka actually works internally. The author breaks down the development process into five stages, starting with a single broker that has a TCP protocol, persistent log, topics and partitions.
The primary focus of this first stage is to understand the architecture of the log storage layer, which is implemented as directories containing log files. Each record on disk consists of an 8-byte offset, a 8-byte timestamp, a 4-byte key length, the key bytes, a 4-byte value length, and the value bytes. The author emphasizes the importance of understanding the storage layer by implementing it from scratch, rather than relying on an existing embedded database.
The article also provides a brief overview of the remaining stages, which involve adding features such as log segments, retention, consumer groups, offsets, rebalancing, replication, leader election, and a Python SDK for easier integration and testing.
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