Minimal changes to enable tracing context in MDC with coroutines

Uses latest Spring Framework 6.1 snapshots that propagate CoroutineContext in CoWebFilter[1].

[1] spring-projects/spring-framework#27522

Author: shakuzen

app/build.gradle.kts

@@ -1,8 +1,8 @@
 import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
-import org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES
 
 plugins {
-    id("org.springframework.boot") version "3.1.4"
+    id("org.springframework.boot") version "3.2.0-SNAPSHOT"
+    id("io.spring.dependency-management") version "1.1.3"
     kotlin("jvm") version "1.9.10"
     kotlin("plugin.spring") version "1.9.10"
 }
@@ -16,12 +16,12 @@ java {
 
 repositories {
     mavenCentral()
+    maven { url = uri("https://repo.spring.io/milestone") }
+    maven { url = uri("https://repo.spring.io/snapshot") }
 }
 
 dependencies {
-    implementation(platform(BOM_COORDINATES))
     implementation(platform("org.zalando:logbook-bom:3.4.0"))
-    implementation(platform("io.micrometer:micrometer-tracing-bom:1.1.5"))
     implementation("org.springframework.boot:spring-boot-starter-webflux")
     implementation("org.springframework.boot:spring-boot-starter-security")
     runtimeOnly("org.springframework.boot:spring-boot-starter-actuator")
@@ -35,7 +35,7 @@ dependencies {
     implementation("org.zalando:logbook-spring-boot-starter")
     implementation("org.zalando:logbook-spring-boot-webflux-autoconfigure")
     implementation("org.jetbrains.kotlinx:kotlinx-coroutines-slf4j:1.7.3")
-    compileOnly("org.springframework.boot:spring-boot-devtools")
+    developmentOnly("org.springframework.boot:spring-boot-devtools")
     testImplementation("org.springframework.boot:spring-boot-starter-test")
 }
 

app/src/main/kotlin/com/grassehh/app/configuration/TracingConfiguration.kt

@@ -10,15 +10,32 @@ import io.netty.channel.ChannelDuplexHandler
 import io.netty.channel.ChannelHandlerContext
 import io.netty.channel.ChannelPromise
 import jakarta.annotation.PostConstruct
+import kotlinx.coroutines.slf4j.MDCContext
+import kotlinx.coroutines.withContext
 import org.springframework.context.annotation.Bean
 import org.springframework.context.annotation.Configuration
+import org.springframework.web.server.CoWebFilter
+import org.springframework.web.server.CoWebFilterChain
+import org.springframework.web.server.ServerWebExchange
+import org.springframework.web.server.WebFilter
 import reactor.core.publisher.Hooks
 import reactor.netty.Metrics
 
 @Configuration
 class TracingConfiguration(private val observationRegistry: ObservationRegistry, private val tracer: Tracer) {
+
+    @Bean
+    fun coroutineWebFilter(): WebFilter {
+        return object : CoWebFilter() {
+            override suspend fun filter(exchange: ServerWebExchange, chain: CoWebFilterChain)
+                    = withContext(MDCContext()) {
+                chain.filter(exchange)
+            }
+        }
+    }
+
     @Bean
-    fun contextSnapshotFactory() = ContextSnapshotFactory.builder().build()
+    fun contextSnapshotFactory() = ContextSnapshotFactory.builder().build();
 
     @PostConstruct
     fun postConstruct() {

settings.gradle.kts

@@ -1,2 +1,10 @@
+pluginManagement {
+    repositories {
+        maven { url = uri("https://repo.spring.io/milestone") }
+        maven { url = uri("https://repo.spring.io/snapshot") }
+        gradlePluginPortal()
+    }
+}
+
 rootProject.name = "spring-boot-3-tracing-coroutine"
 include("app")