add metrics configuration so that histogram (bucket) is enabled for http.client metrics from webclient (http_client_requests_seconds_bucket).

Co-authored-by: Jan Schawo <[email protected]>

Author: frankbregulla1111

core/src/main/kotlin/de/otto/babbage/core/config/ClientRequestMetricsTagContributor.kt

@@ -0,0 +1,30 @@
+package de.otto.babbage.core.config
+
+import io.micrometer.common.KeyValue
+import io.micrometer.common.KeyValues
+import org.springframework.boot.actuate.metrics.http.Outcome
+import org.springframework.web.reactive.function.client.ClientRequest
+import org.springframework.web.reactive.function.client.ClientRequestObservationContext
+import org.springframework.web.reactive.function.client.DefaultClientRequestObservationConvention
+
+class ClientRequestMetricsTagContributor : DefaultClientRequestObservationConvention() {
+
+    override fun getLowCardinalityKeyValues(context: ClientRequestObservationContext): KeyValues {
+        return KeyValues.of(
+            KeyValue.of("method", context.request?.method()?.name() ?: "undefined"),
+            KeyValue.of("uri", extractFirstPath(context.request)),
+            KeyValue.of("client.name", context.request?.url()?.host ?: "none"),
+            KeyValue.of("status", context.response?.statusCode()?.value()?.toString() ?: "undefined"),
+            KeyValue.of("outcome", context.response?.statusCode()?.value()?.let { Outcome.forStatus(it).toString() } ?: Outcome.UNKNOWN.toString())
+        )
+    }
+
+    private fun extractFirstPath(request: ClientRequest?): String {
+        return if (request != null) {
+            "/" + request.url().path.split("/").firstOrNull { it.isNotBlank() }
+        } else {
+            "undefined"
+        }
+    }
+
+}

core/src/main/kotlin/de/otto/babbage/core/config/MetricConfiguration.kt

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+package de.otto.babbage.core.config
+
+import io.micrometer.core.instrument.Meter
+import io.micrometer.core.instrument.MeterRegistry
+import io.micrometer.core.instrument.config.MeterFilter
+import io.micrometer.core.instrument.distribution.DistributionStatisticConfig
+import org.springframework.boot.actuate.autoconfigure.metrics.MeterRegistryCustomizer
+import org.springframework.context.annotation.Bean
+import org.springframework.context.annotation.Configuration
+
+@Configuration
+class MetricConfiguration {
+
+    @Bean
+    fun clientRequestMetricsTagContributor(): ClientRequestMetricsTagContributor {
+        return ClientRequestMetricsTagContributor()
+    }
+
+    @Bean
+    fun meterRegistryCustomizer(): MeterRegistryCustomizer<MeterRegistry> =
+        MeterRegistryCustomizer<MeterRegistry> { registry ->
+            registry.config()
+                .meterFilter(object : MeterFilter {
+                    override fun configure(id: Meter.Id, config: DistributionStatisticConfig): DistributionStatisticConfig {
+                        return if (id.name.startsWith("http.client")) {
+                            config.merge(DistributionStatisticConfig.builder().percentilesHistogram(true).build())
+                        } else {
+                            config
+                        }
+                    }
+
+                })
+        }
+}

core/src/test/kotlin/de/otto/babbage/core/config/ClientRequestMetricsTagContributorTest.kt

@@ -0,0 +1,51 @@
+package de.otto.babbage.core.config
+
+import io.kotest.matchers.collections.shouldContain
+import io.micrometer.common.KeyValue
+import org.junit.jupiter.api.Test
+import org.mockito.Mockito
+import org.springframework.http.HttpMethod
+import org.springframework.http.HttpStatusCode
+import org.springframework.web.reactive.function.client.ClientRequest
+import org.springframework.web.reactive.function.client.ClientRequestObservationContext
+import org.springframework.web.reactive.function.client.ClientResponse
+import java.net.URI
+
+internal class ClientRequestMetricsTagContributorTest {
+
+    @Test
+    fun `should create key value pairs for web client request`() {
+        // given
+        val url = "http://www.otto.de/first/second/third"
+        val clientRequest = ClientRequest.create(HttpMethod.GET, URI.create(url))
+        val clientResponse = ClientResponse.create(HttpStatusCode.valueOf(200)).build()
+        val observationContext = ClientRequestObservationContext(clientRequest)
+        observationContext.setResponse(clientResponse)
+
+        // when
+        val result = ClientRequestMetricsTagContributor().getLowCardinalityKeyValues(observationContext)
+
+        // then
+        result shouldContain KeyValue.of("method", "GET")
+        result shouldContain KeyValue.of("uri", "/first")
+        result shouldContain KeyValue.of("client.name", "www.otto.de")
+        result shouldContain KeyValue.of("status", "200")
+        result shouldContain KeyValue.of("outcome", "SUCCESS")
+    }
+
+    @Test
+    fun `should create fallback key value pairs for empty request`() {
+        // given
+        val mockedContext = Mockito.mock(ClientRequestObservationContext::class.java)
+
+        // when
+        val result = ClientRequestMetricsTagContributor().getLowCardinalityKeyValues(mockedContext)
+
+        // then
+        result shouldContain KeyValue.of("method", "undefined")
+        result shouldContain KeyValue.of("uri", "undefined")
+        result shouldContain KeyValue.of("client.name", "none")
+        result shouldContain KeyValue.of("status", "undefined")
+        result shouldContain KeyValue.of("outcome", "UNKNOWN")
+    }
+}