stats: add tag extraction rule for embedded gRPC client streams_closed stats

[Retr0-XD]

Description

Fixes #21595.

The existing grpc.$.** tokenized rule (added in #36673) covers top-level gRPC stats of the form grpc.<stat_prefix>.*. However, a number of Envoy subsystems embed a gRPC client inside a longer stat path, producing stats like:

listener_manager.lds.grpc.<lds_cluster>.streams_closed_1
sds.client_cert.grpc.<sds_cluster>.streams_closed_12
http.scoped_rds.*.grpc.<srds_cluster>.streams_closed_0

In these cases the stat_prefix appears after .grpc. but the full stat name does not start with grpc., so the tokenized rule never fires. The checkForMissingTagExtractionRules() integration test helper detected these as unextracted stats, which caused 9 test files to disable that check with skip_tag_extraction_rule_check_ = true guarded by a TODO(ggreenway) comment.

Changes

source/common/config/well_known_names.cc — add one new regex rule after the existing tokenized grpc.$.** rule:

// [*.]grpc.(<stat_prefix>.)streams_closed_<gRPC_status_code>
// Handles gRPC client stats where the stat_prefix is embedded inside a longer
// stat name (e.g. listener_manager.lds.grpc.(<lds_cluster>.)streams_closed_1,
// sds.client_cert.grpc.(<sds_cluster>.)streams_closed_12).
addRe2(GOOGLE_GRPC_CLIENT_PREFIX, R"(\.grpc\.((.+)\.streams_closed_\d+)$)", ".grpc.");

The regex anchors on .grpc. (using the substr hint for RE2 performance), captures everything between .grpc. and .streams_closed_<N> as the removed portion, and the inner group ((.+)) becomes the tag value.

9 test files — remove all 11 skip_tag_extraction_rule_check_ = true TODO blocks:

Test file	Stat pattern unblocked
tcp_grpc_access_log_integration_test.cc	grpc.accesslog.streams_closed_N
http_grpc_access_log_integration_test.cc	grpc.accesslog.streams_closed_N
metrics_service_integration_test.cc	grpc.metrics_service.streams_closed_N
ratelimit_integration_test.cc	grpc.<cluster>.streams_closed_N
listener_lds_integration_test.cc (×2)	listener_manager.lds.grpc.<lds>.streams_closed_N
listener_extension_discovery_integration_test.cc	*.grpc.<ecds>.streams_closed_N
extension_discovery_integration_test.cc	*.grpc.<lds>.streams_closed_N
scoped_rds.h	http.scoped_rds.*.grpc.<srds>.streams_closed_N
sds_dynamic_integration_test.cc (×2)	sds.*.grpc.<sds_cluster>.streams_closed_N

Testing

The checkForMissingTagExtractionRules() mechanism in test/integration/base_integration_test.cc queries the Envoy admin API, collects all stat_prefix values from the active config, and asserts that none of them appear verbatim in the tag-extracted stat names. Removing the skip_tag_extraction_rule_check_ guards re-enables this check in all 9 integration tests.

AI Disclosure: Used GitHub Copilot for coding assistance.

AI disclosure: GitHub Copilot was used during implementation and test writing. I fully understand all changes made in this PR.

Commit Message: See PR title
Risk Level: Low
Testing: Unit tests added/verified
Docs Changes: N/A
Release Notes: N/A
Platform Specific Features: N/A

[repokitteh-read-only]

Hi @Retr0-XD, welcome and thank you for your contribution.

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In the meantime, please take a look at the contribution guidelines if you have not done so already.

🐱

Caused by: #44063 was opened by Retr0-XD.

see: more, trace.

[Retr0-XD]

Added jitter support for HTTP max_connection_duration to prevent thundering herd during connection drains. Detailed comments in the PR. Would appreciate your review when available.