A## - Add List endpoint to gRPC Health service

A##-list-health.md

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+# Add List endpoint to gRPC Health service
+
+* **Author(s):** Marcos Huck.
+* **Approver:** TBD
+* **Status:** Draft  
+* **Implemented in:** TBD
+* **Last updated:** 2024-12-17  
+* **Discussion at:** TBD
+
+
+## Abstract
+
+This proposal introduces a new `List` RPC endpoint for the Health service, allowing clients to retrieve the statuses of all monitored services or a filtered list of specific services. This feature simplifies integration with status-reporting dashboards and enhances observability for microservices.
+
+## Background
+
+The existing Health service provides basic health check functionality but lacks a mechanism to retrieve a comprehensive list of all monitored servicesand their statuses. 
+
+This limitation makes it challenging for clients to aggregate health information across multiple services, particularly for use cases like publishing service statuses to dashboards such as [Cachet](https://cachethq.io/) or [Statuspage](https://www.atlassian.com/software/statuspage).
+
+Kubernetes provides a similar capability with its `/readyz?verbose` endpoint, which lists the status of all components.This proposal aims to bring analogous functionality to the Health service, providing a unified view of service health.
+
+### Related Proposals
+
+N/A
+
+## Proposal
+
+Introduce a new `List` RPC endpoint in the Health service with the following features:
+
+- Retrieve the health statuses of all monitored services or a filtered list of specified services.
+- Ensure the implementation is idempotent and side-effect free.
+- Provide a clear schema for the request and response to facilitate integration with external tools.
+
+### Proposed API Changes
+
+https://github.com/grpc/grpc-proto/pull/143
+
+### Temporary environment variable protection
+
+N/A
+
+## Rationale
+
+Adding the List RPC endpoint to the Health service strikes a balance between functionality and simplicity.
+
+### Alternative approaches
+- Separate Service: Extract the new functionality into a standalone service. This avoids altering the existing Health service API but increases complexity by introducing another service for clients to interact with.
+
+## Implementation
+
+1. Add the `List` RPC endpoint and the associated request/response messages in the Health service .proto file.
+2. Update client libraries to support the `List` endpoint. Provide examples demonstrating how to call the endpoint and handle its response.
+3. Unit tests to validate the behavior of the new endpoint.
+4. Update API documentation to describe the new endpoint, its use cases, and sample requests/responses.
+
+## Open issues (if applicable)
+
+N/A