pprof is a mature, production-grade profiling visualization and analysis tool for Go, C++, Java, and other languages that export profiles in the pprof protobuf format. It operates as both a command-line tool and an interactive web server, allowing users to inspect CPU, memory, contention, and goroutine profiles. The core architecture is a modular Go application: the `driver` package orchestrates fetching, symbolization, merging, and report generation; the `profile` package provides a standalone library for reading, writing, and manipulating profiles; the `graph` package builds weighted directed call graphs; and the `report` package outputs a variety of formats including text, SVG dot graphs, HTML flame graphs, annotated source, disassembly, and more. External dependencies include binutils (addr2line, nm, objdump) for local symbolization, Graphviz (dot) for graph rendering, and optionally Chrome for browser tests. The system supports profile comparison, filtering by tags or sample labels, and can symbolize using local binaries or remote symbolz services. The profile package is designed for reuse as a standalone library, making pprof useful both as a tool and as a data processing foundation for other profiling tooling.
octocov is a Go CLI tool and GitHub Action for collecting, analyzing, and reporting code metrics. It measures code coverage (supporting Go cover, LCOV, SimpleCov, Clover, Cobertura, JaCoCo), code-to-test ratio, test execution time, and custom user-defined metrics. The tool integrates deeply with GitHub: it comments on pull requests, posts job summaries, generates SVG badges, uploads artifacts, and stores reports in configurable datastores (local, S3, GCS, BigQuery, GitHub artifacts, Mackerel). It also supports a central mode that aggregates reports from multiple repositories into a single index with per-repo badges. The architecture is a single Go binary with a Cobra CLI. Key entry points are the root command (cmd/root.go) which orchestrates the CI workflow, and subcommands for badge generation, diff comparison, report dump, and central aggregation. Configuration is via YAML (config/). The coverage package contains format-specific parsers that normalize reports into a common model. The datastore package provides a clean interface for storing/retrieving reports, with implementations for each backend. The badge package renders SVG badges using an embedded template and font. The internal page package serves a React-based viewer for coverage diffs. Primary data flow: Parse coverage files from CI (or local), compute metrics, optionally compare with previous report from a datastore, generate badges/comments/summaries, store the new report. Custom metrics are ingested via environment variable files and validated against a JSON schema. Acceptable conditions (using expr-lang) allow failing CI when metrics regress beyond thresholds. External dependencies include GitHub API (google/go-github), AWS SDK, GCP SDK, BigQuery client, Mackerel API, and a JS bundle for the viewer.
Air is a command-line live-reload utility for Go application development. It watches a project directory for file changes, automatically rebuilds the project using a configurable build command, and restarts the resulting binary. The tool includes an embedded HTTP reverse proxy that injects a JavaScript snippet into HTML responses, enabling automatic browser reload via Server-Sent Events after each successful rebuild. It supports custom build commands, pre/post hooks, environment file loading, platform-specific build overrides, and watch rules that run commands instead of triggering a full rebuild (e.g., for frontend asset pipelines or code generation). The architecture is a single Go binary with a main event loop that uses filesystem notifications (or polling) to detect changes, spawns build processes, and manages child process lifecycle. The codebase is well-structured with clear separation of concerns: configuration parsing (runner/config.go), engine orchestration (runner/engine.go), file watching (runner/watcher.go), HTTP proxy (runner/proxy.go), and platform-specific process management (runner/util_*.go). It includes a comprehensive test suite and CI pipelines for Linux, macOS, and Windows. The proxy component, in particular, demonstrates sophisticated handling of content encoding (gzip, brotli), streaming responses (SSE, chunked transfer), and hop-by-hop header management, making it a reusable pattern for adding live-reload capabilities to any Go web application.
KubeHound is a security analysis tool for Kubernetes clusters that automatically models and computes attack paths. It collects Kubernetes resources (pods, roles, bindings, endpoints, nodes) via a live API or offline dump, transforms them into a property graph stored in JanusGraph (with MongoDB as an intermediate store), and computes privilege escalation and lateral movement paths mapped to MITRE ATT&CK techniques. The system exposes a CLI for local analysis and a gRPC API (KHaaS) for service-oriented deployments, with optional Jupyter notebooks for querying the graph using a custom Gremlin DSL. The architecture is modular: a collector abstraction handles rate-limited streaming from the Kubernetes API; an ingestion pipeline converts raw objects into normalized store models and graph vertices/edges; an edge registry defines over 20 attack types (e.g., PodExec, TokenSteal, ContainerEscape); and a graph builder executes Gremlin traversals to connect vertices into paths. Storage layers use asynchronous writers with micro-batching for high throughput, and an in-memory cache deduplicates identities and roles. Telemetry (Datadog APM, metrics, logs) is integrated throughout. While primarily an application, the repository includes experimental research components (exp/khaudit) for audit reports and MITRE Attack Flow conversion, plus Jupyter notebooks for interactive graph queries, giving it a hybrid character. The codebase demonstrates strong engineering practices: provider interfaces, test mocking, worker pools, retry logic, and comprehensive system tests against real Kind clusters. However, some areas (large cluster optimizations, experimental code, deprecated flags) indicate ongoing evolution and minor technical debt.
Goblin is a web application that serves as a Go binary distribution service, allowing users to download and install Go binaries without having Go installed locally. The application consists of a Go-based HTTP server that resolves package versions from the Go proxy and GitHub, compiles binaries for requested OS/architecture combinations, and serves them to users. It includes a web frontend for documentation and usage examples, Docker configuration for easy deployment, and optional caching via S3-compatible storage. The architecture follows a standard web service pattern with clear separation between API handling, version resolution, binary building, and storage layers.