query-frontend: Fix panic in ResponseToSamples when resp.Data is nil #11571
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Adds nil check to prevent panic when HTTP error responses (like 511 cluster validation errors) are incorrectly parsed as successful responses, resulting in PrometheusResponse objects with Data = nil. The fix converts the panic to a graceful error return, making the function defensive and consistent with other patterns in the codebase. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
Tests cover various scenarios where responses might not be valid Prometheus responses: - Arbitrary JSON objects that don't match the Prometheus schema - Malformed JSON (arrays, strings, numbers instead of objects) - Invalid JSON syntax (missing braces, trailing commas, unescaped quotes) - Different content types (text/plain, text/html, application/xml) - Large payloads and special characters (unicode, emojis) - Error status codes with and without content-type headers These tests ensure the codec handles edge cases gracefully and that ResponseToSamples properly handles responses with nil data instead of panicking.
Signed-off-by: Dimitar Dimitrov <dimitar.dimitrov@grafana.com>
Signed-off-by: Dimitar Dimitrov <dimitar.dimitrov@grafana.com>
- Consolidate all edge case tests into single TestPrometheusCodec_ResponseParsingEdgeCases function - Add multiple status codes per test case to validate behavior across different HTTP response codes - Add special characters test case using anonymous function for unicode, emoji, and special characters - Add large payload test case using anonymous function to generate 10k item JSON array - Remove separate test functions to reduce code duplication - Ensure all tests validate that ResponseToSamples handles nil data gracefully Tests now cover comprehensive edge cases with various status codes: - 200 (success), 400/404 (client errors), 500/503/511 (server errors), 429/413 (rate limiting)
Signed-off-by: Dimitar Dimitrov <dimitar.dimitrov@grafana.com>
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Fixes a panic in
ResponseToSampleswhen HTTP error responses (like 511 cluster validation errors) are incorrectly parsed as successful responses, resulting in PrometheusResponse objects withData = nil.The function was directly accessing
resp.Data.ResultTypewithout checking ifresp.Datais nil, causing runtime panics when malformed responses are processed.This could happen when the remote response was a JSON response which wasn't actually a valid prometheus response. For example this may happen when the cluster validation middleware responds with