Hi Henry, Thanks for working on this interesting feature for the upcoming 3.3 Airflow release. Yes, I lean toward option A.
Additionally, we could even make the API server disable the metrics middleware if user explicitly sets the `api_path_prefix_to_surface` as None, With option A plus the None-aware handling, we can support the metrics middleware with the further extensibility and the feature toggling. Best, Jason On Sun, Jun 21, 2026 at 3:26 PM Henry Chen <[email protected]> wrote: > Hi everyone, > > I would like to start a discussion regarding the configuration design for > the new REST API and UI metrics feature currently being proposed in PR > #64523 <https://github.com/apache/airflow/pull/64523>. > > The core capability adds request monitoring (QPS, latency, and errors) to > Airflow’s FastAPI/Starlette stack. While there is general agreement that > having these metrics in production would be highly valuable, we have hit a > architectural design question regarding how users should configure these > metrics, and we’d love to get the community's feedback. > The Core Question > > How flexible should the mapping between URL prefixes and metric tags ( > api_surface) be for end-users? Currently, we have two design directions: > Option A (Current PR Design): Fully User-Configurable via JSON > > Allows deployment managers to define a custom mapping in airflow.cfg > (e.g., {"/api/v2": > "public", "/ui": "ui", "/execution": "execution", "/my-plugin": "plugin"}). > > - > > *Pros:* High flexibility. It allows users to gain metrics coverage for > additional custom mounted APIs, Execution APIs, or third-party plugin > routes without needing Airflow core code changes. > - > > *Cons:* Adds slightly more complexity to the configuration. > > Option B (Alternative Suggestion): Hardcoded in Code with Simple Toggles > > Airflow maintainers hardcode the specific route-to-tag mappings (e.g., > strictly /api/v2 and /ui) directly in the codebase. Users would only have a > simple boolean flag to turn the metrics on or off, but cannot customize the > URL-to-tag mappings. > > - > > *Pros:* Simpler configuration, lower cognitive load for the average > user. > - > > *Cons:* Lacks extensibility for custom plugins or enterprise-specific > API extensions. > > Discussion Context > > Jason suggested that allowing users to define the mapping themselves > (Option A) provides the necessary extensibility for production environments > where custom plugins or additional mounted endpoints are heavily utilized. > On the other hand, ashb raised concerns about whether users actually need > this level of configurability and whether it duplicates existing metric > filtering mechanisms. > I really appreciate Jason, ashb, Pierre, and Jens taking the time to share > their insights on this. > > We would appreciate your thoughts on which approach makes more sense for > Airflow's architecture moving forward. > > You can find the full discussion and implementation details in the PR here: > https://github.com/apache/airflow/pull/64523 > > Thanks, > Henry >
