$ show dnsimple/erldns
The erldns repository is an Erlang/OTP-based authoritative DNS server that processes DNS queries through a modular pipeline architecture. It loads zone data from JSON or standard zone files, provides DNSSEC validation and signing, and includes features like query throttling, EDNS0 processing, and an HTTP-based Admin API for runtime zone management and monitoring. The system is built using OTP supervision trees, with separate supervisors for listeners, pipeline workers, and zone loading. Key architectural strengths include a reusable pipeline pattern for extensible query processing, a worker pool for asynchronous operations, a segmented cache abstraction for high-concurrency scenarios, and admission control mechanisms using CoDel and Cubic algorithms. The Admin API follows a middleware pattern allowing custom extensions, and the zone loading subsystem supports pluggable codecs for custom record types. The codebase demonstrates strong engineering practices with comprehensive testing, dependency management, and observability via telemetry.
The LLM identified 3 files worth highlighting for reuse:
Defines a modular pipeline for DNS query processing where each stage implements prepare/1, call/2, and deps/0 callbacks. Stages declare dependencies and are composed dynamically, allowing extensible and isolated processing logic (e.g., question extraction, resolution, DNSSEC validation). This pattern enables safe reuse in other data processing pipelines.
Implements a bounded worker pool for asynchronous task execution using the worker_pool library. Provides a simple interface for submitting jobs and handling results with back-pressure control. This abstraction is safely reusable in any Erlang application requiring concurrent workload management with resource limits.
Implements the CoDel (Controlled Delay) algorithm for network admission control to prevent bufferbloat and manage latency under load. The module is self-contained, exports a clear API for enqueueing packets with timing-based dropping logic, and can be extracted for use in other network servers or proxies requiring intelligent load shedding.