Micrometer rate limit

Status: Stable Package: dev.vertique.micrometer.ratelimit Artifact: vertique-micrometer-rate-limit Depends on: vertique-rate-limit-core, vertique-micrometer-core, micrometer-core API reference: javadoc.io

vertique-micrometer-rate-limit is the optional Micrometer adapter for the provider-neutral rate-limiting runtime. It contributes exactly one RateLimitObserver implementation; the rate-limit runtime stays free of a Micrometer dependency without it, and installing vertique-rate-limit-core alone contributes no observer and emits no telemetry.

When To Use It

Install MicrometerRateLimitModule alongside MicrometerModule and the application’s rate-limit modules (RateLimitCoreModule, and vertique-rate-limit-redis for CLUSTERED policies) when decision, rejection, and failure metrics are wanted:

@Component(modules = {
    VertxModule.class,
    RateLimitCoreModule.class,
    MicrometerModule.class,
    MicrometerRateLimitModule.class
})
interface AppComponent {}

Core Concepts

The adapter is subject to the same redaction constraint as the events it consumes: no key, identity, or IP material ever reaches a metric tag. policy (the event’s policyName) is the only per-request-shape dimension it emits, and it joins the same shared cardinality-guard key union the other Vertique Micrometer adapters use.

Meters

Prefix: vertique.ratelimit..

Meter	Type	Tags	Recorded
vertique.ratelimit.decision	Timer	policy, outcome, mode	Once per RateLimitDecisionCompleted event, regardless of outcome; records the event’s backend latency
vertique.ratelimit.rejections	Counter	policy	Once per event where outcome == QUOTA_EXCEEDED
vertique.ratelimit.failures	Counter	policy, code, mode	Once per event where outcome is BACKEND_FAILURE_OPEN or BACKEND_FAILURE_CLOSED; code is the event’s failureCode

vertique.ratelimit.rejections and vertique.ratelimit.failures are strict subsets of the decision timer’s count. No gauges are registered: isolated runtime scopes make an aggregate gauge misleading, the same rationale vertique-micrometer-resilience documents for its own meters.

Only the policy name, outcome, mode, and failure code become labels — key, identity, IP, exception, and message are never labels. This module performs no label validation of its own: policy, outcome, mode, and code are taken from the event as-is, and the only bound on their cardinality is the shared cardinality guard installed by vertique-micrometer-core (see its module.md).

Configuration

This module owns no configuration keys. It follows the global metrics.enabled switch through the optional MetricsConfig: when MicrometerModule supplies a MetricsConfig, metrics.enabled=false silences the adapter; when no MetricsConfig binding exists the optional is empty and the adapter is enabled.

Key Classes

MicrometerRateLimitModule

Dagger @Module (public, abstract, not instantiable). It includes the generated GeneratedRegistrationsModule, which contributes one RateLimitObserver into Set<RateLimitObserver>, and declares @BindsOptionalOf MetricsConfig metricsConfig() so that observer can inject Optional<MetricsConfig> without requiring MicrometerModule. Install it in the application component; it is the module’s only application-facing type.

Module Dagger Bindings

Binding	Kind	Description
MetricsConfig	@BindsOptionalOf	Declared for adapter enablement checks; the adapter can be used with or without MicrometerModule as long as a MeterRegistry binding is present
RateLimitObserver	@RegisterIntoSet	The metrics observer, wired through the generated GeneratedRegistrationsModule this module includes

Verification

./mvnw -ntp -pl vertique-micrometer/vertique-micrometer-rate-limit -am verify

Dependencies

Artifact	Purpose
vertique-rate-limit-core	Provides the RateLimitObserver SPI and RateLimitDecisionCompleted events
vertique-micrometer-core	Provides the application MeterRegistry and metrics configuration when MicrometerModule is installed
micrometer-core	Timers, counters, tags, and registry APIs