feat: add auto-instrumentation support for Java 8+ (#228)

Signed-off-by: Michele Mancioppi <[email protected]>

.github/dependabot.yml

@@ -25,7 +25,14 @@ updates:
       development-dependencies:
         dependency-type: "development"
 
+  # Dash0 OpenTelemetry Distro for Node.js
   - package-ecosystem: "npm"
     directory: "images/instrumentation/node.js/"
     schedule:
       interval: "daily"
+
+  # OpenTelemetry Java agent
+  - package-ecosystem: "maven"
+    directory: "images/instrumentation/jvm/"
+    schedule:
+      interval: "daily"

.github/workflows/ci.yaml

@@ -77,7 +77,7 @@ jobs:
   injector_binary_and_instrumentation_image_tests:
     name: Injector Binary & Instrumentation Image Tests
     runs-on: ubuntu-latest
-    timeout-minutes: 20
+    timeout-minutes: 40
     steps:
       - uses: actions/checkout@v4
 

helm-chart/dash0-operator/README.md

@@ -21,7 +21,8 @@ The Dash0 operator is currently available as a technical preview.
 
 Supported runtimes for automatic workload instrumentation:
 
-* Node.js 18 and beyond
+* Java 8+
+* Node.js 18+
 
 Other features like metrics and log collection are independent of the runtime of workloads.
 
@@ -878,7 +879,7 @@ Prometheus Rule Synchronization Results:
 ## Notes on Running The Operator on Apple Silicon
 
 When running the operator on an Apple Silicon host (M1, M3 etc.), for example via Docker Desktop, some attention needs
-to be paid to the CPU architecture of images. The architcture of the Kubernetes node for this scenario will be `arm64`.
+to be paid to the CPU architecture of images. The architecture of the Kubernetes node for this scenario will be `arm64`.
 When running a single-architecture `amd64` image (as opposed to a single-architecture `arm64` image or a
 [multi-platform build](https://docs.docker.com/build/building/multi-platform/) containing `amd64` as well as `arm64`)
 the operator will prevent the container from starting.

images/instrumentation/Dockerfile

@@ -16,9 +16,17 @@ RUN gcc \
   src/dash0_injector.c \
   -o dash0_injector.so
 
+# download OpenTelemetry Java agent
+FROM openjdk:24-jdk-bookworm AS build-jvm
+COPY jvm /dash0-init-container/instrumentation/jvm
+WORKDIR /dash0-init-container/instrumentation/jvm
+RUN ./mvnw dependency:copy-dependencies \
+  && cp ./target/dependency/opentelemetry-javaagent-*.jar ./build/opentelemetry-javaagent.jar \
+  && cp pom.xml ./build/pom.xml
+
 # build Node.js artifacts
 FROM node:20.13.1-alpine3.19 AS build-node.js
-RUN mkdir -p /instrumentation/node.js
+RUN mkdir -p /dash0-init-container/instrumentation/node.js
 WORKDIR /dash0-init-container/instrumentation/node.js
 COPY node.js/package* ./
 COPY node.js/dash0hq-opentelemetry-*.tgz .
@@ -36,6 +44,7 @@ COPY copy-instrumentation.sh /
 # copy artifacts (distros, injector binary) from the build stages to the final image
 RUN mkdir -p /dash0-init-container/instrumentation
 COPY --from=build-injector /dash0-init-container/dash0_injector.so /dash0-init-container/dash0_injector.so
+COPY --from=build-jvm /dash0-init-container/instrumentation/jvm/build /dash0-init-container/instrumentation/jvm
 COPY --from=build-node.js /dash0-init-container/instrumentation/node.js /dash0-init-container/instrumentation/node.js
 
 WORKDIR /

images/instrumentation/injector/src/dash0_injector.c

@@ -7,6 +7,10 @@
 #define HIGHS (ONES * (UCHAR_MAX / 2 + 1))
 #define HASZERO(x) ((x) - ONES & ~(x) & HIGHS)
 
+#define JAVA_TOOL_OPTIONS_ENV_VAR_NAME "JAVA_TOOL_OPTIONS"
+#define JAVA_TOOL_OPTIONS_DASH0_REQUIRE                                        \
+  "-javaagent:"                                                                \
+  "/__dash0__/instrumentation/jvm/opentelemetry-javaagent.jar"
 #define NODE_OPTIONS_ENV_VAR_NAME "NODE_OPTIONS"
 #define NODE_OPTIONS_DASH0_REQUIRE                                             \
   "--require "                                                                 \
@@ -92,103 +96,149 @@ char *__getenv(const char *name) {
  * the program manipulated values of env vars without dynamic allocations.
  */
 char cachedModifiedOtelResourceAttributesValue[1012];
-char cachedModifiedNodeOptionsValue[1012];
+char cachedModifiedRuntimeOptionsValue[1012];
+
+char *__appendResourceAttributes(const char *buffer, const char *origValue) {
+  char *namespaceName = __getenv(DASH0_NAMESPACE_NAME_ENV_VAR_NAME);
+  char *podUid = __getenv(DASH0_POD_UID_ENV_VAR_NAME);
+  char *podName = __getenv(DASH0_POD_NAME_ENV_VAR_NAME);
+  char *containerName = __getenv(DASH0_POD_CONTAINER_NAME_VAR_NAME);
+
+  int attributeCount = 0;
+
+  /*
+   * We do not perform octect escaping in the resource attributes as
+   * specified in
+   * https://opentelemetry.io/docs/specs/otel/resource/sdk/#specifying-resource-information-via-an-environment-variable
+   * because the values that are passed down to the injector comes from
+   * fields that Kubernetes already enforces to either conform to RFC 1035
+   * or RFC RFC 1123
+   * (https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#dns-label-names),
+   * and in either case, none of the characters allowed require escaping
+   * based on https://www.w3.org/TR/baggage/#header-content
+   */
+
+  if (namespaceName != NULL && __strlen(namespaceName) > 0) {
+    __strcat(buffer, "k8s.namespace.name=");
+    __strcat(buffer, namespaceName);
+    attributeCount += 1;
+  }
+
+  if (podName != NULL && __strlen(podName) > 0) {
+    if (attributeCount > 0) {
+      __strcat(buffer, ",");
+    }
+
+    __strcat(buffer, "k8s.pod.name=");
+    __strcat(buffer, podName);
+    attributeCount += 1;
+  }
+
+  if (podUid != NULL && __strlen(podUid) > 0) {
+    if (attributeCount > 0) {
+      __strcat(buffer, ",");
+    }
+
+    __strcat(buffer, "k8s.pod.uid=");
+    __strcat(buffer, podUid);
+    attributeCount += 1;
+  }
+
+  if (containerName != NULL && __strlen(containerName) > 0) {
+    if (attributeCount > 0) {
+      __strcat(buffer, ",");
+    }
+
+    __strcat(buffer, "k8s.container.name=");
+    __strcat(buffer, containerName);
+    attributeCount += 1;
+  }
+
+  if (origValue != NULL && __strlen(origValue) > 0) {
+    if (attributeCount > 0) {
+      __strcat(buffer, ",");
+    }
+
+    __strcat(buffer, origValue);
+  }
+}
 
 char *getenv(const char *name) {
   char *origValue = __getenv(name);
   int l = __strlen(name);
 
   char *otelResourceAttributesVarName = OTEL_RESOURCE_ATTRIBUTES_ENV_VAR_NAME;
+  char *javaToolOptionsVarName = JAVA_TOOL_OPTIONS_ENV_VAR_NAME;
   char *nodeOptionsVarName = NODE_OPTIONS_ENV_VAR_NAME;
   if (__strcmp(name, otelResourceAttributesVarName) == 0) {
     if (__strlen(cachedModifiedOtelResourceAttributesValue) == 0) {
       // This environment variable (OTEL_RESOURCE_ATTRIBUTES) has not been
       // requested before, calculate the modified value and cache it.
-      char *namespaceName = __getenv(DASH0_NAMESPACE_NAME_ENV_VAR_NAME);
-      char *podUid = __getenv(DASH0_POD_UID_ENV_VAR_NAME);
-      char *podName = __getenv(DASH0_POD_NAME_ENV_VAR_NAME);
-      char *containerName = __getenv(DASH0_POD_CONTAINER_NAME_VAR_NAME);
-
-      int attributeCount = 0;
-
-      /*
-       * We do not perform octect escaping in the resource attributes as
-       * specified in
-       * https://opentelemetry.io/docs/specs/otel/resource/sdk/#specifying-resource-information-via-an-environment-variable
-       * because the values that are passed down to the injector comes from
-       * fields that Kubernetes already enforces to either conform to RFC 1035
-       * or RFC RFC 1123
-       * (https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#dns-label-names),
-       * and in either case, none of the characters allowed require escaping
-       * based on https://www.w3.org/TR/baggage/#header-content
-       */
-
-      if (namespaceName != NULL && __strlen(namespaceName) > 0) {
-        __strcat(cachedModifiedOtelResourceAttributesValue,
-                 "k8s.namespace.name=");
-        __strcat(cachedModifiedOtelResourceAttributesValue, namespaceName);
-        attributeCount += 1;
-      }
-
-      if (podName != NULL && __strlen(podName) > 0) {
-        if (attributeCount > 0) {
-          __strcat(cachedModifiedOtelResourceAttributesValue, ",");
-        }
-
-        __strcat(cachedModifiedOtelResourceAttributesValue, "k8s.pod.name=");
-        __strcat(cachedModifiedOtelResourceAttributesValue, podName);
-        attributeCount += 1;
-      }
-
-      if (podUid != NULL && __strlen(podUid) > 0) {
-        if (attributeCount > 0) {
-          __strcat(cachedModifiedOtelResourceAttributesValue, ",");
-        }
-
-        __strcat(cachedModifiedOtelResourceAttributesValue, "k8s.pod.uid=");
-        __strcat(cachedModifiedOtelResourceAttributesValue, podUid);
-        attributeCount += 1;
-      }
+      __appendResourceAttributes(cachedModifiedOtelResourceAttributesValue,
+                                 origValue);
+    }
 
-      if (containerName != NULL && __strlen(containerName) > 0) {
-        if (attributeCount > 0) {
-          __strcat(cachedModifiedOtelResourceAttributesValue, ",");
-        }
+    return cachedModifiedOtelResourceAttributesValue;
+  } else if (__strcmp(name, javaToolOptionsVarName) == 0) {
+    if (__strlen(cachedModifiedRuntimeOptionsValue) == 0) {
+      // No runtime environment variable has been requested before,
+      // calculate the modified value and cache it.
 
-        __strcat(cachedModifiedOtelResourceAttributesValue,
-                 "k8s.container.name=");
-        __strcat(cachedModifiedOtelResourceAttributesValue, containerName);
-        attributeCount += 1;
-      }
+      // Prepend our --require as the first item to the JAVA_TOOL_OPTIONS
+      // string.
+      char *javaToolOptionsDash0Require = JAVA_TOOL_OPTIONS_DASH0_REQUIRE;
+      __strcat(cachedModifiedRuntimeOptionsValue, javaToolOptionsDash0Require);
+
+      // The Java runtime does not look up the OTEL_RESOURCE_ATTRIBUTES env var
+      // using getenv(), but rather by parsing the environment block
+      // (/proc/env/<pid>) directly, which we cannot affect with the getenv
+      // hook. So, instead, we append the resource attributes as the
+      // -Dotel.resource.attributes Java system property.
+      // If the -Dotel.resource.attributes system property is already set,
+      // the user-defined property will take precedence:
+      //
+      // % JAVA_TOOL_OPTIONS="-Dprop=B" jshell -R -Dprop=A
+      // Picked up JAVA_TOOL_OPTIONS: -Dprop=B
+      // |  Welcome to JShell -- Version 17.0.12
+      // |  For an introduction type: /help intro
+      //
+      // jshell> System.getProperty("prop")
+      // $1 ==> "A"
+
+      char *otelResourceAttributesViaEnv =
+          __getenv(OTEL_RESOURCE_ATTRIBUTES_ENV_VAR_NAME);
+      __strcat(cachedModifiedRuntimeOptionsValue,
+               " -Dotel.resource.attributes=");
+      __appendResourceAttributes(cachedModifiedRuntimeOptionsValue,
+                                 otelResourceAttributesViaEnv);
 
       if (origValue != NULL && __strlen(origValue) > 0) {
-        if (attributeCount > 0) {
-          __strcat(cachedModifiedOtelResourceAttributesValue, ",");
-        }
-
-        __strcat(cachedModifiedOtelResourceAttributesValue, origValue);
+        // If JAVA_TOOL_OPTIONS were present, append the existing
+        // JAVA_TOOL_OPTIONS after our --javaagent.
+        __strcat(cachedModifiedRuntimeOptionsValue, " ");
+        __strcat(cachedModifiedRuntimeOptionsValue, origValue);
       }
     }
 
-    return cachedModifiedOtelResourceAttributesValue;
+    return cachedModifiedRuntimeOptionsValue;
   } else if (__strcmp(name, nodeOptionsVarName) == 0) {
-    if (__strlen(cachedModifiedNodeOptionsValue) == 0) {
-      // This environment variable (NODE_OPTIONS) has not been requested before,
+    if (__strlen(cachedModifiedRuntimeOptionsValue) == 0) {
+      // No runtime environment variable has been requested before,
       // calculate the modified value and cache it.
 
       // Prepend our --require as the first item to the NODE_OPTIONS string.
       char *nodeOptionsDash0Require = NODE_OPTIONS_DASH0_REQUIRE;
-      __strcat(cachedModifiedNodeOptionsValue, nodeOptionsDash0Require);
+      __strcat(cachedModifiedRuntimeOptionsValue, nodeOptionsDash0Require);
 
       if (origValue != NULL && __strlen(origValue) > 0) {
         // If NODE_OPTIONS were present, append the existing NODE_OPTIONS after
         // our --require.
-        __strcat(cachedModifiedNodeOptionsValue, " ");
-        __strcat(cachedModifiedNodeOptionsValue, origValue);
+        __strcat(cachedModifiedRuntimeOptionsValue, " ");
+        __strcat(cachedModifiedRuntimeOptionsValue, origValue);
       }
     }
 
-    return cachedModifiedNodeOptionsValue;
+    return cachedModifiedRuntimeOptionsValue;
   }
 
   return origValue;

images/instrumentation/jvm/.gitignore

@@ -0,0 +1,14 @@
+# Download
+build/*
+
+# Maven
+target/
+pom.xml.tag
+pom.xml.releaseBackup
+pom.xml.versionsBackup
+pom.xml.next
+release.properties
+dependency-reduced-pom.xml
+buildNumber.properties
+.mvn/timing.properties
+.mvn/wrapper/maven-wrapper.jar

images/instrumentation/jvm/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,19 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+wrapperVersion=3.3.2
+distributionType=only-script
+distributionUrl=https://repo.maven.apache.org/maven2/org/apache/maven/apache-maven/3.9.9/apache-maven-3.9.9-bin.zip

images/instrumentation/jvm/README.md

@@ -0,0 +1,10 @@
+# JVM instrumentation
+
+We currently do not have a Dash0 distro for Java.
+Rather, we use the upstream [OpenTelemetry Java agent](https://github.com/open-telemetry/opentelemetry-java-instrumentation).
+The version of the OTel Java agent to be used is specified in the [local `pom.xml`](./pom.xml) file.
+Maven can download the correct version of the OTel Java agent by running:
+
+```shell
+./mvnw dependency:copy-dependencies
+```