Shields.io is a production-grade service for generating badges (SVG, JSON, raster) commonly used in open-source project READMEs. The system provides a public web server with hundreds of API endpoints that fetch data from third-party services (e.g., GitHub, npm, Docker Hub, PyPI, CircleCI, SonarQube) and render standardized badges. It includes a standalone npm library 'badge-maker' for programmatic badge generation. The architecture is a Node.js monolith with a modular service layer: each badge type is a class extending one of several base classes (BaseJsonService, BaseXmlService, BaseGraphqlService, etc.) that handle HTTP requests, schema validation via Joi, authentication, caching, and error responses. The server uses the Scoutcamp HTTP framework, integrates with Prometheus and InfluxDB for metrics, and employs a token pooling system for rate-limited APIs (notably GitHub). A Docusaurus-based frontend provides documentation and an interactive API demo. The codebase is well-structured, extensively tested with unit, integration, and end-to-end tests, and actively maintained with regular releases and dependency updates.
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.