go-grpc-middleware is a library of interceptor middleware for Go gRPC applications.
The library addresses the need to implement cross-cutting concerns in gRPC services without duplicating logic across handlers. gRPC interceptors execute before requests reach application logic on the server side, or wrap client calls, making them ideal for implementing patterns like authentication, logging, tracing, metrics, validation, retries, and rate limiting. The tool provides ready-to-use middleware implementations that can be chained together, allowing a single interceptor chain to handle observability signals, authentication, and panic recovery consistently across all gRPC methods in a service.
Developers should adopt this library when building Go microservices that need standard cross-cutting concerns implemented consistently. It works well for teams wanting to avoid reimplementing auth, logging, and observability patterns across multiple services. The README notes that some interceptors are intentionally simple to write and suggests copying them if you need more flexibility for edge cases your project requires. For authentication, the library provides a customizable auth middleware via AuthFunc, while acknowledging that more complex authorization needs may be better served by external solutions like the RBAC-style policies available in grpc-go itself.
The project maintains a curated list of known interceptors used in Go microservices, including both implementations in this repository and external alternatives, with examples available for each. The README explicitly encourages using the repository as a template and copying simpler interceptors when greater flexibility is needed, indicating the maintainers recognize this library cannot support all edge cases users might encounter. The project includes buildable examples demonstrating interceptor chaining patterns and observability correlation techniques.
