Add initial OSGi support

all/build.gradle.kts

@@ -4,6 +4,7 @@ plugins {
 
 description = "OpenTelemetry All"
 otelJava.moduleName.set("io.opentelemetry.all")
+otelJava.osgiEnabled.set(false)
 
 // Skip ossIndexAudit on test module
 tasks.named("ossIndexAudit") {

animal-sniffer-signature/build.gradle.kts

@@ -8,6 +8,7 @@ plugins {
 
 description = "Build tool to generate the Animal Sniffer Android signature"
 otelJava.moduleName.set("io.opentelemetry.internal.animalsniffer")
+otelJava.osgiEnabled.set(false)
 
 val signatureJar = configurations.create("signatureJar") {
   isCanBeConsumed = false

api/all/build.gradle.kts

@@ -9,6 +9,10 @@ plugins {
 description = "OpenTelemetry API"
 otelJava.moduleName.set("io.opentelemetry.api")
 base.archivesName.set("opentelemetry-api")
+// These packages cannot be compileOnly dependencies (api:incubator depends on api:all, creating a
+// circular dependency; sdk:autoconfigure is in a different module family). Declare them as optional
+// imports without a version constraint so OSGi wires them if present but does not require them.
+otelJava.osgiUnversionedOptionalPackages.set(listOf("io.opentelemetry.sdk.autoconfigure", "io.opentelemetry.api.incubator", "io.opentelemetry.api.incubator.internal"))
 
 dependencies {
   api(project(":context"))

api/incubator/build.gradle.kts

@@ -8,6 +8,7 @@ plugins {
 
 description = "OpenTelemetry API Incubator"
 otelJava.moduleName.set("io.opentelemetry.api.incubator")
+otelJava.osgiOptionalPackages.set(listOf("com.fasterxml.jackson.databind"))
 
 dependencies {
   api(project(":api:all"))

api/testing-internal/build.gradle.kts

@@ -4,6 +4,7 @@ plugins {
 
 description = "OpenTelemetry API Testing (Internal)"
 otelJava.moduleName.set("io.opentelemetry.api.testing.internal")
+otelJava.osgiEnabled.set(false)
 
 dependencies {
   api(project(":api:all"))

buildSrc/build.gradle.kts

@@ -33,6 +33,7 @@ repositories {
 }
 
 dependencies {
+  implementation("biz.aQute.bnd:biz.aQute.bnd.gradle:7.2.0")
   implementation(enforcedPlatform("com.squareup.wire:wire-bom:6.2.0"))
   implementation("com.google.auto.value:auto-value-annotations:1.11.1")
   // When updating, update above in plugins too

buildSrc/src/main/kotlin/io/opentelemetry/gradle/OtelJavaExtension.kt

@@ -6,14 +6,29 @@
 package io.opentelemetry.gradle
 
 import org.gradle.api.JavaVersion
+import org.gradle.api.provider.ListProperty
 import org.gradle.api.provider.Property
 
 abstract class OtelJavaExtension {
     abstract val moduleName: Property<String>
 
+    // Set to false for modules that are not OSGi bundles (e.g. test helpers, build tooling,
+    // aggregators). Skips BND bundle metadata generation entirely.
+    abstract val osgiEnabled: Property<Boolean>
+
+    abstract val osgiOptionalPackages: ListProperty<String>
+
+    // Packages that should be optional imports but are not on the compile classpath (e.g. due to
+    // circular dependencies), so BND cannot resolve version="${@}" for them. Added to Import-Package
+    // with resolution:=optional but no version constraint.
+    abstract val osgiUnversionedOptionalPackages: ListProperty<String>
+
     abstract val minJavaVersionSupported: Property<JavaVersion>
 
     init {
         minJavaVersionSupported.convention(JavaVersion.VERSION_1_8)
+        osgiEnabled.convention(true)
+        osgiOptionalPackages.convention(emptyList<String>())
+        osgiUnversionedOptionalPackages.convention(emptyList<String>())
     }
 }

buildSrc/src/main/kotlin/otel.java-conventions.gradle.kts

@@ -9,6 +9,7 @@ plugins {
   eclipse
   idea
 
+  id("biz.aQute.bnd.builder")
   id("otel.errorprone-conventions")
   id("otel.jacoco-conventions")
   id("otel.spotless-conventions")
@@ -131,6 +132,38 @@ tasks {
     }
   }
 
+  afterEvaluate {
+    if (otelJava.osgiEnabled.get()) {
+      named<Jar>("jar") {
+        // Configure OSGi metadata
+        bundle {
+          // Compute import packages.
+          // Certain packages like javax.annotation.* are always optional.
+          // Modules may have additional optional packages, typically corresponding to compileOnly dependencies.
+          // Append wildcard "*" last to import any other referenced packages.
+          val optionalPackages = mutableListOf("javax.annotation")
+          optionalPackages.addAll(otelJava.osgiOptionalPackages.get())
+          val importPackages = optionalPackages.joinToString(",") { "$it.*;resolution:=optional;version=\"\${@}\"" } + ",*"
+
+          // Packages not on the compile classpath (e.g. due to circular dependencies) cannot use
+          // version="${@}" since BND cannot resolve the version. Add them as optional imports without
+          // a version constraint; they are listed before the wildcard so BND uses our explicit
+          // instruction rather than auto-detecting them with a version.
+          val unversionedOptionalPackages = otelJava.osgiUnversionedOptionalPackages.get()
+          val unversionedImports = unversionedOptionalPackages.joinToString(",") { "$it.*;resolution:=optional" }
+          val fullImportPackages = if (unversionedImports.isNotEmpty()) "$unversionedImports,$importPackages" else importPackages
+
+          bnd(mapOf(
+            // Exclude shaded internal packages from exports; they are implementation details and
+            // should not be part of the OSGi bundle's public API surface.
+            "-exportcontents" to "!io.opentelemetry.internal.shaded.*,io.opentelemetry.*",
+            "Import-Package" to fullImportPackages
+          ))
+        }
+      }
+    }
+  }
+
   withType<Jar>().configureEach {
     inputs.property("moduleName", otelJava.moduleName)
 

dependencyManagement/build.gradle.kts

@@ -36,6 +36,7 @@ val DEPENDENCY_BOMS = listOf(
   "io.zipkin.brave:brave-bom:6.3.1",
   "io.zipkin.reporter2:zipkin-reporter-bom:3.5.3",
   "org.assertj:assertj-bom:3.27.7",
+  "org.osgi:org.osgi.test.bom:1.2.1",
   "org.testcontainers:testcontainers-bom:2.0.4",
   "org.snakeyaml:snakeyaml-engine:2.10"
 )
@@ -88,11 +89,13 @@ val DEPENDENCIES = listOf(
   "io.opentracing:opentracing-noop:0.33.0",
   "junit:junit:4.13.2",
   "nl.jqno.equalsverifier:equalsverifier:3.19.4",
+  "org.apache.felix:org.apache.felix.framework:7.0.5",
   "org.awaitility:awaitility:4.3.0",
   "org.codehaus.mojo:animal-sniffer-annotations:1.27",
   "org.jctools:jctools-core:4.0.6",
   "org.junit-pioneer:junit-pioneer:1.9.1",
   "org.mock-server:mockserver-netty:5.15.0:shaded",
+  "org.osgi:osgi.core:8.0.0",
   "org.skyscreamer:jsonassert:1.5.3",
   "com.android.tools:desugar_jdk_libs:2.1.5",
 )

exporters/common/compile-stub/build.gradle.kts

@@ -4,3 +4,4 @@ plugins {
 
 description = "OpenTelemetry Exporter Compile Stub"
 otelJava.moduleName.set("io.opentelemetry.exporter.internal.compile-stub")
+otelJava.osgiEnabled.set(false)

integration-tests/build.gradle.kts

@@ -4,6 +4,7 @@ plugins {
 
 description = "OpenTelemetry Integration Tests"
 otelJava.moduleName.set("io.opentelemetry.integration.tests")
+otelJava.osgiEnabled.set(false)
 
 dependencies {
   testImplementation(project(":sdk:all"))

integration-tests/graal-incubating/build.gradle.kts

@@ -7,6 +7,7 @@ plugins {
 
 description = "OpenTelemetry Graal Integration Tests (Incubating)"
 otelJava.moduleName.set("io.opentelemetry.graal.integration.tests.incubating")
+otelJava.osgiEnabled.set(false)
 otelJava.minJavaVersionSupported.set(JavaVersion.VERSION_17)
 
 sourceSets {

integration-tests/graal/build.gradle.kts

@@ -7,6 +7,7 @@ plugins {
 
 description = "OpenTelemetry Graal Integration Tests"
 otelJava.moduleName.set("io.opentelemetry.graal.integration.tests")
+otelJava.osgiEnabled.set(false)
 otelJava.minJavaVersionSupported.set(JavaVersion.VERSION_17)
 
 sourceSets {

integration-tests/osgi/build.gradle.kts

@@ -0,0 +1,111 @@
+import aQute.bnd.gradle.Bundle
+import aQute.bnd.gradle.Resolve
+import aQute.bnd.gradle.TestOSGi
+
+plugins {
+  id("otel.java-conventions")
+}
+
+description = "OpenTelemetry OSGi Integration Tests"
+otelJava.moduleName.set("io.opentelemetry.integration.tests.osgi")
+
+// For similar test examples see:
+// https://github.com/micrometer-metrics/micrometer/tree/main/micrometer-osgi-test
+// https://github.com/eclipse-osgi-technology/osgi-test/tree/main/examples/osgi-test-example-gradle
+
+configurations.all {
+  resolutionStrategy {
+    // BND not compatible with JUnit 5.13+; see https://github.com/bndtools/bnd/issues/6651
+    val junitVersion = "5.12.2"
+    val junitLauncherVersion = "1.12.1"
+    force("org.junit.jupiter:junit-jupiter:$junitVersion")
+    force("org.junit.jupiter:junit-jupiter-api:$junitVersion")
+    force("org.junit.jupiter:junit-jupiter-params:$junitVersion")
+    force("org.junit.jupiter:junit-jupiter-engine:$junitVersion")
+    force("org.junit.platform:junit-platform-launcher:$junitLauncherVersion")
+  }
+}
+
+dependencies {
+  // Testing the "kitchen sink" hides OSGi configuration issues. For example, opentelemetry-api has
+  // optional dependencies on :sdk-extensions:autoconfigure and :api:incubator. If we only test a
+  // bundle which includes those, then mask the fact that OSGi fails when using a bundle without those
+  // until opentelemetry-api OSGi configuration is updated to indicate that they are optional.
+
+  // TODO (jack-berg): Add additional test bundles with dependency combinations reflecting popular use cases:
+  // - with OTLP exporters
+  // - with autoconfigure
+  // - with file configuration
+  testImplementation(project(":sdk:all"))
+
+  testImplementation("org.junit.jupiter:junit-jupiter")
+
+  testCompileOnly("org.osgi:osgi.core")
+  testImplementation("org.osgi:org.osgi.test.junit5")
+  testImplementation("org.osgi:org.osgi.test.assertj.framework")
+  testRuntimeOnly("org.junit.platform:junit-platform-launcher")
+  testRuntimeOnly("org.apache.felix:org.apache.felix.framework")
+}
+
+val testingBundleTask = tasks.register<Bundle>("testingBundle") {
+  archiveClassifier.set("testing")
+  from(sourceSets.test.get().output)
+  bundle {
+    // The Bundle task uses compileClasspath by default for BND analysis (e.g. resolving the
+    // @Testable annotation to populate Test-Cases). Without this, testImplementation dependencies
+    // like junit-jupiter are invisible to BND, causing Test-Cases to be empty and 0 tests to run.
+    classpath(sourceSets.test.get().runtimeClasspath)
+    bnd(
+      "Test-Cases: \${classes;HIERARCHY_INDIRECTLY_ANNOTATED;org.junit.platform.commons.annotation.Testable;CONCRETE}",
+      "Import-Package: javax.annotation.*;resolution:=optional;version=\"\${@}\",*"
+    )
+  }
+}
+
+val resolveTask = tasks.register<Resolve>("resolve") {
+  dependsOn(testingBundleTask)
+  project.ext.set("osgiRunee", "JavaSE-${java.toolchain.languageVersion.get()}")
+  description = "Resolve test.bndrun"
+  group = JavaBasePlugin.VERIFICATION_GROUP
+  bndrun = file("test.bndrun")
+  outputBndrun = layout.buildDirectory.file("test.bndrun")
+  bundles = files(sourceSets.test.get().runtimeClasspath, testingBundleTask.get().archiveFile)
+  // The generated output embeds an absolute path to the source bndrun, making it unsafe to share
+  // across machines or worktrees via the build cache.
+  outputs.cacheIf { false }
+}
+
+val testOSGiTask = tasks.register<TestOSGi>("testOSGi") {
+  description = "OSGi Test test.bndrun"
+  group = JavaBasePlugin.VERIFICATION_GROUP
+  bndrun = resolveTask.flatMap { it.outputBndrun }
+  bundles = files(sourceSets.test.get().runtimeClasspath, testingBundleTask.get().archiveFile)
+  // BND reports success when zero tests ran (e.g. if bundles failed to start). Fail explicitly.
+  val testResultsDir = layout.buildDirectory.dir("test-results/testOSGi")
+  doLast {
+    check(testResultsDir.get().asFile.listFiles()?.isNotEmpty() == true) {
+      "No OSGi test results found — bundles may have failed to start. Check the output above."
+    }
+  }
+}
+
+tasks.named(LifecycleBasePlugin.CHECK_TASK_NAME) {
+  dependsOn(testOSGiTask)
+}
+
+tasks {
+  jar {
+    enabled = false
+  }
+  test {
+    // We need to replace junit testing with the testOSGi task, so we clear test actions and add a dependency on testOSGi.
+    // As a result, running :test runs only :testOSGi.
+    actions.clear()
+    dependsOn(testOSGiTask)
+  }
+}
+
+// Skip ossIndexAudit on test module
+tasks.named("ossIndexAudit") {
+  enabled = false
+}