prometheus/web/api/testhelpers
Julien 75f94903b3
Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825)
* Add OpenAPI 3.2 specification generation for Prometheus HTTP API

This commit introduces an OpenAPI specification for the Prometheus API.
After testing multiple code-generation servers with built-in APIs, this
implementation uses an independent spec file outside of the critical path.
This spec file is tested with a framework present in this pull request.

The specification helps clients know which parameters they can use and is
served at /api/v1/openapi.yaml. The spec file will evolve with the
Prometheus API and has the same version number.

Downstream projects can tune the APIs presented in the spec file with
configuration options using the IncludePaths setting for path filtering.

In the future, there is room to generate a server from this spec file
(e.g. with interfaces), but this is out of scope for this pull request.

Architecture:
- Core OpenAPI infrastructure (openapi.go): Dynamic spec building,
  caching, and thread-safe spec generation
- Schema definitions (openapi_schemas.go): Complete type definitions
  for all API request and response types
- Path specifications (openapi_paths.go): Endpoint definitions with
  parameters, request bodies, and response schemas
- Examples (openapi_examples.go): Realistic request/response examples
- Helper functions (openapi_helpers.go): Reusable builders for common
  OpenAPI structures

Testing:
- Comprehensive test suite with golden file validation
- Test helpers package for API testing infrastructure
- OpenAPI compliance validation utilities

The golden file captures the complete specification for snapshot testing.
Update with: go test -run TestOpenAPIGolden -update-openapi-spec

REVIEWERS: The most important thing to check would be the OpenAPI golden
file (web/api/v1/testdata/openapi_golden.yaml). Test scenarios are important
as they test the actual OpenAPI spec validity.

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>

* Add OpenAPI 3.1 support with version selection

Add support for both OpenAPI 3.1 and 3.2 specifications with version
selection via openapi_version query parameter. Defaults to 3.1 for
broader compatibility

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>

* Enhance OpenAPI examples and add helper functions

- Add timestampExamples helper for consistent time formatting
- Add exampleMap helper to simplify example creation
- Improve example summaries with query details
- Add matrix result example for range vector queries

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>

* web/api: Add AtST method to test helper iterators

Implement the AtST() method required by chunkenc.Iterator interface
for FakeSeriesIterator and FakeHistogramSeriesIterator test helpers.
The method returns 0 as these test helpers don't use start timestamps

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>

* OpenAPI: Add minimum coverage test

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>

* OpenAPI: Improve examples handling

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>

---------

Signed-off-by: Julien Pivotto <291750+roidelapluie@users.noreply.github.com>
2026-01-29 13:36:13 +01:00
..
api.go Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825) 2026-01-29 13:36:13 +01:00
assertions.go Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825) 2026-01-29 13:36:13 +01:00
fixtures.go Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825) 2026-01-29 13:36:13 +01:00
mocks.go Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825) 2026-01-29 13:36:13 +01:00
openapi.go Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825) 2026-01-29 13:36:13 +01:00
request.go Add OpenAPI 3.2 specification generation for Prometheus HTTP API (#17825) 2026-01-29 13:36:13 +01:00