fix(rt): slf4j 1.x compatability

.changes/d7863388-cf31-44d7-b613-c2376e853b97.json

@@ -0,0 +1,8 @@
+{
+    "id": "d7863388-cf31-44d7-b613-c2376e853b97",
+    "type": "bugfix",
+    "description": "Provide SLF4J 1.x compatible fallback implementation",
+    "issues": [
+        "awslabs/aws-sdk-kotlin#993"
+    ]
+}

build.gradle.kts

@@ -127,6 +127,8 @@ apiValidation {
             "paginator-tests",
             "waiter-tests",
             "compile",
+            "slf4j-1x-consumer",
+            "slf4j-2x-consumer",
         ),
     )
 }

gradle/libs.versions.toml

@@ -9,6 +9,7 @@ okhttp-version = "5.0.0-alpha.11"
 okio-version = "3.3.0"
 otel-version = "1.27.0"
 slf4j-version = "2.0.6"
+slf4j-v1x-version = "1.7.36"
 crt-kotlin-version = "0.7.1"
 
 # codegen
@@ -51,6 +52,7 @@ okhttp-coroutines = { module = "com.squareup.okhttp3:okhttp-coroutines", version
 opentelemetry-api = { module = "io.opentelemetry:opentelemetry-api", version.ref = "otel-version" }
 opentelemetry-sdk-testing = {module = "io.opentelemetry:opentelemetry-sdk-testing", version.ref = "otel-version" }
 slf4j-api = { module = "org.slf4j:slf4j-api", version.ref = "slf4j-version" }
+slf4j-api-v1x = { module = "org.slf4j:slf4j-api", version.ref = "slf4j-v1x-version" }
 slf4j-simple = { module = "org.slf4j:slf4j-simple", version.ref = "slf4j-version" }
 crt-kotlin = { module = "aws.sdk.kotlin.crt:aws-crt-kotlin", version.ref = "crt-kotlin-version" }
 

runtime/observability/logging-slf4j2/build.gradle.kts

@@ -2,8 +2,8 @@
  * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
  * SPDX-License-Identifier: Apache-2.0
  */
-description = "Logging provider based on SLF4J 2"
-extra["displayName"] = "Smithy :: Kotlin :: Observability :: SLF4J2 binding"
+description = "Logging provider based on SLF4J"
+extra["displayName"] = "Smithy :: Kotlin :: Observability :: SLF4J binding"
 extra["moduleName"] = "aws.smithy.kotlin.runtime.telemetry"
 
 kotlin {

runtime/observability/logging-slf4j2/jvm/src/aws/smithy/kotlin/runtime/telemetry/logging/slf4j/AbstractSlf4jLoggerAdapter.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package aws.smithy.kotlin.runtime.telemetry.logging.slf4j
+
+import aws.smithy.kotlin.runtime.telemetry.logging.LogLevel
+import aws.smithy.kotlin.runtime.telemetry.logging.Logger
+
+/**
+ * Common functionality across SLF4J 1.x and 2.x
+ * @param delegate the underlying slf4j logger instance
+ */
+internal abstract class AbstractSlf4jLoggerAdapter(protected val delegate: org.slf4j.Logger) : Logger {
+    override fun trace(t: Throwable?, msg: () -> String) {
+        if (!isEnabledFor(LogLevel.Trace)) return
+        if (t != null) {
+            delegate.trace(msg(), t)
+        } else {
+            delegate.trace(msg())
+        }
+    }
+    override fun debug(t: Throwable?, msg: () -> String) {
+        if (!isEnabledFor(LogLevel.Debug)) return
+        if (t != null) {
+            delegate.debug(msg(), t)
+        } else {
+            delegate.debug(msg())
+        }
+    }
+    override fun info(t: Throwable?, msg: () -> String) {
+        if (!isEnabledFor(LogLevel.Info)) return
+        if (t != null) {
+            delegate.info(msg(), t)
+        } else {
+            delegate.info(msg())
+        }
+    }
+    override fun warn(t: Throwable?, msg: () -> String) {
+        if (!isEnabledFor(LogLevel.Warning)) return
+        if (t != null) {
+            delegate.warn(msg(), t)
+        } else {
+            delegate.warn(msg())
+        }
+    }
+    override fun error(t: Throwable?, msg: () -> String) {
+        if (!isEnabledFor(LogLevel.Error)) return
+        if (t != null) {
+            delegate.error(msg(), t)
+        } else {
+            delegate.error(msg())
+        }
+    }
+    override fun isEnabledFor(level: LogLevel): Boolean = when (level) {
+        LogLevel.Trace -> delegate.isTraceEnabled
+        LogLevel.Debug -> delegate.isDebugEnabled
+        LogLevel.Info -> delegate.isInfoEnabled
+        LogLevel.Warning -> delegate.isWarnEnabled
+        LogLevel.Error -> delegate.isErrorEnabled
+    }
+}

runtime/observability/logging-slf4j2/jvm/src/aws/smithy/kotlin/runtime/telemetry/logging/slf4j/Slf4j1xLoggerAdapter.kt

@@ -0,0 +1,78 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package aws.smithy.kotlin.runtime.telemetry.logging.slf4j
+
+import aws.smithy.kotlin.runtime.telemetry.context.Context
+import aws.smithy.kotlin.runtime.telemetry.logging.LogLevel
+import aws.smithy.kotlin.runtime.telemetry.logging.LogRecordBuilder
+import aws.smithy.kotlin.runtime.telemetry.logging.LoggerProvider
+import org.slf4j.MDC
+
+private val noOpLogRecordBuilder = LoggerProvider.None.getOrCreateLogger("NoOpLogger").atLevel(LogLevel.Error)
+
+/**
+ * SLF4J 1.x based logger
+ */
+internal class Slf4j1xLoggerAdapter(logger: org.slf4j.Logger) : AbstractSlf4jLoggerAdapter(logger) {
+    override fun atLevel(level: LogLevel): LogRecordBuilder = if (isEnabledFor(level)) {
+        Slf4j1xLogRecordBuilderAdapter(this, level)
+    } else {
+        noOpLogRecordBuilder
+    }
+}
+
+private class Slf4j1xLogRecordBuilderAdapter(
+    private val delegate: Slf4j1xLoggerAdapter,
+    private val level: LogLevel,
+) : LogRecordBuilder {
+
+    private var msg: (() -> String)? = null
+    private var cause: Throwable? = null
+    private val kvp by lazy { mutableMapOf<String, Any>() }
+    override fun setCause(ex: Throwable) {
+        cause = ex
+    }
+
+    override fun setMessage(message: String) {
+        msg = { message }
+    }
+
+    override fun setMessage(message: () -> String) {
+        msg = message
+    }
+
+    override fun setKeyValuePair(key: String, value: Any) {
+        kvp[key] = value
+    }
+
+    override fun setContext(context: Context) {
+        // TODO - add a way to get the current trace context and set the key/value pair on it?
+    }
+
+    override fun emit() {
+        val message = requireNotNull(msg) { "no message provided to LogRecordBuilder" }
+        val logMethod = when (level) {
+            LogLevel.Error -> delegate::error
+            LogLevel.Warning -> delegate::warn
+            LogLevel.Info -> delegate::info
+            LogLevel.Debug -> delegate::debug
+            LogLevel.Trace -> delegate::trace
+        }
+
+        if (kvp.isNotEmpty()) {
+            val prevCtx = MDC.getCopyOfContextMap()
+            try {
+                kvp.forEach { (k, v) ->
+                    MDC.put(k, v.toString())
+                }
+                logMethod(cause, message)
+            } finally {
+                MDC.setContextMap(prevCtx)
+            }
+        } else {
+            logMethod(cause, message)
+        }
+    }
+}

runtime/observability/logging-slf4j2/jvm/src/aws/smithy/kotlin/runtime/telemetry/logging/slf4j/Slf4j2xLoggerAdapter.kt

@@ -0,0 +1,54 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+package aws.smithy.kotlin.runtime.telemetry.logging.slf4j
+
+import aws.smithy.kotlin.runtime.telemetry.context.Context
+import aws.smithy.kotlin.runtime.telemetry.logging.LogLevel
+import aws.smithy.kotlin.runtime.telemetry.logging.LogRecordBuilder
+import org.slf4j.event.Level
+import org.slf4j.spi.LoggingEventBuilder
+
+/**
+ * SLF4J 2.x based logger
+ */
+internal class Slf4j2xLoggerAdapter(logger: org.slf4j.Logger) : AbstractSlf4jLoggerAdapter(logger) {
+    override fun atLevel(level: LogLevel): LogRecordBuilder =
+        Slf4j2xLogRecordBuilderAdapter(delegate.atLevel(level.slf4jLevel))
+}
+
+private class Slf4j2xLogRecordBuilderAdapter(
+    private val delegate: LoggingEventBuilder,
+) : LogRecordBuilder {
+    override fun setCause(ex: Throwable) {
+        delegate.setCause(ex)
+    }
+
+    override fun setMessage(message: String) {
+        delegate.setMessage(message)
+    }
+
+    override fun setMessage(message: () -> String) {
+        delegate.setMessage(message)
+    }
+
+    override fun setKeyValuePair(key: String, value: Any) {
+        delegate.addKeyValue(key, value)
+    }
+
+    override fun setContext(context: Context) {
+        // TODO - add a way to get the current trace context and set the key/value pair on it?
+    }
+
+    override fun emit() = delegate.log()
+}
+
+private val LogLevel.slf4jLevel: org.slf4j.event.Level
+    get() = when (this) {
+        LogLevel.Error -> Level.ERROR
+        LogLevel.Warning -> Level.WARN
+        LogLevel.Info -> Level.INFO
+        LogLevel.Debug -> Level.DEBUG
+        LogLevel.Trace -> Level.TRACE
+    }

runtime/observability/logging-slf4j2/jvm/src/aws/smithy/kotlin/runtime/telemetry/logging/slf4j/Slf4jLoggerProvider.kt

@@ -5,73 +5,28 @@
 
 package aws.smithy.kotlin.runtime.telemetry.logging.slf4j
 
-import aws.smithy.kotlin.runtime.telemetry.context.Context
 import aws.smithy.kotlin.runtime.telemetry.logging.*
 import org.slf4j.LoggerFactory
-import org.slf4j.event.Level
-import org.slf4j.spi.LoggingEventBuilder
 
 /**
- * SLF4J 2 based logger provider
+ * SLF4J based logger provider
  */
 public object Slf4jLoggerProvider : LoggerProvider {
-    override fun getOrCreateLogger(name: String): Logger {
-        val sl4fjLogger = LoggerFactory.getLogger(name)
-        return Slf4JLoggerAdapter(sl4fjLogger)
-    }
-}
-
-private class Slf4JLoggerAdapter(private val delegate: org.slf4j.Logger) : Logger {
-    private fun logWith(t: Throwable?, msg: () -> String, builder: LoggingEventBuilder) =
-        builder.setMessage(msg)
-            .apply {
-                if (t != null) {
-                    setCause(t)
-                }
-            }.log()
-    override fun trace(t: Throwable?, msg: () -> String) = logWith(t, msg, delegate.atTrace())
-    override fun debug(t: Throwable?, msg: () -> String) = logWith(t, msg, delegate.atDebug())
-    override fun info(t: Throwable?, msg: () -> String) = logWith(t, msg, delegate.atInfo())
-    override fun warn(t: Throwable?, msg: () -> String) = logWith(t, msg, delegate.atWarn())
-    override fun error(t: Throwable?, msg: () -> String) = logWith(t, msg, delegate.atError())
-    override fun isEnabledFor(level: LogLevel): Boolean =
-        delegate.isEnabledForLevel(level.slf4jLevel)
-
-    override fun atLevel(level: LogLevel): LogRecordBuilder =
-        Slf4jLogRecordBuilderAdapter(delegate.atLevel(level.slf4jLevel))
-}
-
-private class Slf4jLogRecordBuilderAdapter(
-    private val delegate: LoggingEventBuilder,
-) : LogRecordBuilder {
-    override fun setCause(ex: Throwable) {
-        delegate.setCause(ex)
-    }
 
-    override fun setMessage(message: String) {
-        delegate.setMessage(message)
+    private val useSlf4j2x = try {
+        Class.forName("org.slf4j.spi.LoggingEventBuilder")
+        true
+    } catch (ex: ClassNotFoundException) {
+        LoggerFactory.getLogger(Slf4jLoggerProvider::class.java).warn("falling back to SLF4J 1.x compatible binding")
+        false
     }
 
-    override fun setMessage(message: () -> String) {
-        delegate.setMessage(message)
-    }
-
-    override fun setKeyValuePair(key: String, value: Any) {
-        delegate.addKeyValue(key, value)
-    }
-
-    override fun setContext(context: Context) {
-        // TODO - add a way to get the current trace context and set the key/value pair on it?
+    override fun getOrCreateLogger(name: String): Logger {
+        val sl4fjLogger = LoggerFactory.getLogger(name)
+        return if (useSlf4j2x) {
+            Slf4j2xLoggerAdapter(sl4fjLogger)
+        } else {
+            Slf4j1xLoggerAdapter(sl4fjLogger)
+        }
     }
-
-    override fun emit() = delegate.log()
 }
-
-private val LogLevel.slf4jLevel: org.slf4j.event.Level
-    get() = when (this) {
-        LogLevel.Error -> Level.ERROR
-        LogLevel.Warning -> Level.WARN
-        LogLevel.Info -> Level.INFO
-        LogLevel.Debug -> Level.DEBUG
-        LogLevel.Trace -> Level.TRACE
-    }

settings.gradle.kts

@@ -78,3 +78,5 @@ include(":tests:benchmarks:serde-benchmarks")
 include(":tests:compile")
 include(":tests:codegen:paginator-tests")
 include(":tests:codegen:waiter-tests")
+include(":tests:integration:slf4j-1x-consumer")
+include(":tests:integration:slf4j-2x-consumer")

tests/integration/slf4j-1x-consumer/build.gradle.kts

@@ -0,0 +1,44 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+import aws.sdk.kotlin.gradle.dsl.skipPublishing
+
+plugins {
+    kotlin("jvm")
+}
+
+skipPublishing()
+
+dependencies {
+    implementation(project(":runtime:observability:logging-slf4j2"))
+    implementation(libs.slf4j.api) {
+        version {
+            strictly(libs.versions.slf4j.v1x.version.get())
+        }
+    }
+    implementation(libs.slf4j.simple) {
+        version {
+            strictly(libs.versions.slf4j.v1x.version.get())
+        }
+    }
+
+    testImplementation(libs.junit.jupiter)
+    testImplementation(libs.kotlin.test)
+    testImplementation(libs.kotlin.test.junit5)
+}
+
+tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
+    kotlinOptions.jvmTarget = "1.8"
+}
+
+tasks.test {
+    useJUnitPlatform()
+    testLogging {
+        events("passed", "skipped", "failed")
+        showStandardStreams = false
+        showStackTraces = true
+        showExceptions = true
+        exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
+    }
+}