fix: remove raw request path label from shenyu_request_type_total (#6671)

[wy471x]

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• You submit test cases (unit or integration tests) that back your changes.
• Your local test passed ./mvnw clean install -Dmaven.javadoc.skip=true.

Summary

Fixes #6671. shenyu_request_type_total was incremented with the raw request path as a
label value, so every distinct path (/api/user/123, /api/order/456, ...) created a new
Counter.Child inside the Prometheus client's internal children map, which is never
evicted. The outer counter/gauge/histogram maps are bounded by metric name, but that
per-series map is not: heap usage grows with the number of distinct request paths, which
is unbounded on a gateway serving parameterised routes, and it also inflates the
/metrics payload. The path label is now dropped, keeping only the bounded rpcType
dimension.

Changes

1. MetricsPlugin#execute (shenyu-plugin/shenyu-plugin-metrics/src/main/java/org/apache/shenyu/plugin/metrics/MetricsPlugin.java:49) — counterIncrement(LabelNames.REQUEST_TYPE_TOTAL, ...) now passes new String[]{shenyuContext.getRpcType()} instead of new String[]{exchange.getRequest().getURI().getRawPath(), shenyuContext.getRpcType()}.

2. MetricsReporter#register (shenyu-plugin/shenyu-plugin-metrics/src/main/java/org/apache/shenyu/plugin/metrics/reporter/MetricsReporter.java:43) — the counter is registered with label names {"type"} instead of {"path", "type"}, so the registration matches the values the plugin emits.

Note for reviewers: this changes the exposed label set of shenyu_request_type_total
from {path,type} to {type}. It is an intentional breaking change to the metric shape,
since per-path granularity cannot be kept without the unbounded cardinality. Dashboards
that break this metric down by path need to be adjusted.

Test Cases

1. MetricsPluginTest.testRequestTypeTotalIsNotLabelledByRawPath (shenyu-plugin/shenyu-plugin-metrics/src/test/java/org/apache/shenyu/plugin/metrics/MetricsPluginTest.java:93) — executes the plugin for /api/user/123 and /api/order/456 and verifies both increments carry the same label vector {rpcType}, i.e. the raw path is no longer forwarded as a label value.

Verification

• ./mvnw -pl shenyu-plugin/shenyu-plugin-metrics clean install -Dmaven.javadoc.skip=true — BUILD SUCCESS; Tests run: 15, Failures: 0, Errors: 0, Skipped: 0.
• ./mvnw clean install -Dmaven.javadoc.skip=true — all modules build and install. The only failure is a pre-existing, order-dependent one in shenyu-kubernetes-controller: DubboReconcilerTest#testReconcile fails when that module's test suite runs as a whole and passes when the class is run in isolation; it is untouched by this PR. Excluding only that class, the remaining reactor finishes green.
• Checkstyle: 0 violations.
• RAT: Unapproved 0, unknown 0, generated 0, approved 17 licenses.

close #6671

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Pull request overview

Removes the raw request path from shenyu_request_type_total to prevent unbounded Prometheus label cardinality.

Changes:

• Uses only rpcType as the request-type metric label.
• Updates Prometheus registration to match the new label vector.
• Adds a regression test for path-independent increments.

File summaries

File	Description
shenyu-plugin/shenyu-plugin-metrics/src/test/java/org/apache/shenyu/plugin/metrics/MetricsPluginTest.java	Updated as part of this pull request.
shenyu-plugin/shenyu-plugin-metrics/src/main/java/org/apache/shenyu/plugin/metrics/reporter/MetricsReporter.java	Updated as part of this pull request.
shenyu-plugin/shenyu-plugin-metrics/src/main/java/org/apache/shenyu/plugin/metrics/MetricsPlugin.java	Updated as part of this pull request.

Review details

Suppressed comments (1)

shenyu-plugin/shenyu-plugin-metrics/src/main/java/org/apache/shenyu/plugin/metrics/reporter/MetricsReporter.java:43

• The regression test only verifies that the plugin passes a one-element value vector to a mock; it never asserts the counter is registered with the matching one-label schema. If this registration accidentally remains {path, type}, the test would still pass even though the Prometheus client rejects the one-value labels(...) call at runtime. Please add a registration assertion (or exercise an actual Prometheus register) that shenyu_request_type_total has exactly the type label.

        MetricsReporter.registerCounter(LabelNames.REQUEST_TYPE_TOTAL, new String[]{"type"}, "shenyu http request type total count");

• Files reviewed: 3/3 changed files
• Comments generated: 1
• Review effort level: Lite

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[Aias00]

Approved as PMC (Aias00). Small, well-scoped fix with regression tests; green CI, mergeable. Reviewed the diff.