A self-contained Go Prometheus exporter that implements a custom collector to scrape Selenium Grid's GraphQL endpoint and expose metrics (nodes, sessions, queue depth, session lifecycle timestamps). It has its own go.mod, is built as a standalone binary, and can be extracted as a reusable pattern for any service with a similar GraphQL API. The architecture separates GraphQL query construction, response parsing, and Prometheus metric collection into distinct files.

A complete, self-contained KEDA external scaler implementation in Go. It implements the ExternalScaler gRPC service, communicating with the Selenium Grid GraphQL endpoint to determine scaling needs based on session queue length and node availability. The code is cleanly organized into separated packages: metadata parsing, core scaling logic, platform mapping, and gRPC server. It has its own Dockerfile and Makefile, and could be adapted to scale other distributed systems by replacing the GraphQL query and logic.

An event-driven video recording service that subscribes to Selenium Grid's ZeroMQ event bus (session-created, session-closed) and manages concurrent ffmpeg processes to record browser sessions. It handles graceful shutdown via SIGTERM, uploads recordings using rclone, and supports session subfolder organization. The design pattern of subscribing to external events, managing child process lifecycles, and implementing a state machine for video file naming and rotation is reusable for any service that needs to capture streams or logs tied to session lifecycles.

A shell script that serves as the container entry point for all Selenium Grid images. It configures environment variables, sets up signal forwarding (SIGTERM/SIGINT) to supervisord for graceful shutdown, handles SELINUX and TZ variables, and generates a unique SE_OTEL_SERVICE_ID. The pattern of using trap to relay signals to a child process manager is generic and could be reused in any containerized application that requires proper shutdown sequencing.