Design Decisions¶

Records significant architectural and library choices made during rsyslog development.

This document records significant architectural and library choices made during the development of rsyslog, providing context for future contributors.

Library Choices¶

Libyaml¶

Context: The introduction of complex configuration objects (e.g., ratelimit()) requiring external policy files necessitated a structured data format. YAML was chosen for its readability and widespread adoption.

Decision: Use libyaml (https://github.com/yaml/libyaml) as the YAML parser.

Reasoning: 1. Portability: libyaml is written in C89, ensuring compatibility with the wide range of legacy and enterprise platforms rsyslog supports (AIX, Solaris, older Linux distributions) without requiring a modern C++ compiler or complex toolchain. 2. Standardization: It is the reference implementation for YAML in C. Widely used wrappers in other languages (Python, Ruby) rely on it, ensuring its behavior is the de-facto standard. 3. Dependencies: It has no external dependencies, keeping rsyslog’s dependency footprint minimal. 4. License: The MIT license is permissive and fully compatible with rsyslog’s licensing model. 5. Alternatives Considered:

libfyaml: While feature-rich and supporting YAML 1.2, it is newer and less proven on obscure architectures compared to libyaml.

libcyaml: Adds a layer of convenience but introduces an additional dependency on top of libyaml.

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