Add OpenTelemetry Javaagent framework

This framework will wire up the OpenTelemetry Javaagent auto instrumentation. It leverages VCAP_SERVICES and the existence of a service binding with a specific name (`otel-collector`).

Author: tylerbenson

config/components.yml

@@ -67,6 +67,7 @@ frameworks:
   - "JavaBuildpack::Framework::MariaDbJDBC"
   - "JavaBuildpack::Framework::MetricWriter"
   - "JavaBuildpack::Framework::NewRelicAgent"
+  - "JavaBuildpack::Framework::OpenTelemetryJavaagent"
   - "JavaBuildpack::Framework::PostgresqlJDBC"
   - "JavaBuildpack::Framework::RiverbedAppinternalsAgent"
   - "JavaBuildpack::Framework::SealightsAgent"

config/opentelemetry_javaagent.yml

@@ -0,0 +1,19 @@
+# Cloud Foundry Java Buildpack
+# Copyright 2013-2023 the original author or authors.
+#
+# Licensed 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.
+
+# Configuration for the OpenTelemetry Javaagent
+---
+version: +
+repository_root: https://raw.githubusercontent.com/open-telemetry/opentelemetry-java-instrumentation/cloudfoundry/

docs/framework-opentelemetry_javaagent.md

@@ -0,0 +1,40 @@
+# OpenTelemetry Javaagent
+
+The OpenTelemetry Javaagent buildpack framework will cause an application to be automatically instrumented
+with the [OpenTelemetry Javaagent Instrumentation](https://github.com/open-telemetry/opentelemetry-java-instrumentation).
+
+Data will be sent directly to the OpenTelemetry Collector. 
+
+<table>
+  <tr>
+    <td><strong>Detection Criterion</strong></td>
+    <td>Existence of a bound service containing the string <code>otel-collector</code></td>
+  </tr>
+  <tr>
+    <td><strong>Tags</strong></td>
+    <td><code>opentelemetry-javaagent=&lt;version&gt;</code></td>
+  </tr>
+</table>
+
+Tags are printed to standard output by the buildpack detect script
+
+## User-Provided Service
+
+Users are currently expected to provide their own "custom user provided service" (cups) 
+instance and bind it to their application. The service MUST contain the string `otel-collector`.
+
+### Choosing a version
+
+Most users should skip this and simply use the latest version of the agent available (the default).
+To override the default and choose a specific version, you can use the `JBP_CONFIG_*` mechanism
+and set the `JBP_CONFIG_OPENTELEMETRY_JAVAAGENT` environment variable for your application.
+
+For example, to use version 1.27.0 of the OpenTelemetry Javaagent Instrumentation, you
+could run:
+```
+$ cf set-env testapp JBP_CONFIG_OPENTELEMETRY_JAVAAGENT '{version: 1.27.0}'
+```
+ 
+# Additional Resources
+
+* [OpenTelemetry Javaagent Instrumentation](https://github.com/open-telemetry/opentelemetry-java-instrumentation) on GitHub

lib/java_buildpack/framework/opentelemetry_javaagent.rb

@@ -0,0 +1,54 @@
+# frozen_string_literal: true
+
+# Cloud Foundry Java Buildpack
+# Copyright 2013-2023 the original author or authors.
+#
+# Licensed 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.
+
+require 'java_buildpack/component/versioned_dependency_component'
+require 'java_buildpack/framework'
+
+module JavaBuildpack
+  module Framework
+
+    # Main class for adding the OpenTelemetry Javaagent instrumentation
+    class OpenTelemetryJavaagent < JavaBuildpack::Component::VersionedDependencyComponent
+
+      # (see JavaBuildpack::Component::BaseComponent#compile)
+      def compile
+        download_jar
+      end
+
+      # (see JavaBuildpack::Component::BaseComponent#release)
+      def release
+        java_opts = @droplet.java_opts
+        java_opts.add_javaagent(@droplet.sandbox + jar_name)
+
+        # Set the otel.service.name to the application_name
+        app_name = @application.details['application_name']
+        java_opts.add_system_property('otel.service.name', app_name)
+      end
+
+      protected
+
+      # (see JavaBuildpack::Component::VersionedDependencyComponent#supports?)
+      def supports?
+        @application.services.one_service? REQUIRED_SERVICE_NAME_FILTER
+      end
+
+      # bound service must contain the string `otel-collector`
+      REQUIRED_SERVICE_NAME_FILTER = /otel-collector/.freeze
+
+    end
+  end
+end

spec/java_buildpack/framework/opentelemtry_javaagent_spec.rb

@@ -0,0 +1,66 @@
+# frozen_string_literal: true
+
+# Cloud Foundry Java Buildpack
+# Copyright 2013-2020 the original author or authors.
+#
+# Licensed 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.
+
+require 'spec_helper'
+require 'component_helper'
+require 'java_buildpack/framework/opentelemetry_javaagent'
+require 'java_buildpack/util/tokenized_version'
+
+describe JavaBuildpack::Framework::OpenTelemetryJavaagent do
+  include_context 'with component help'
+
+  let(:configuration) { { 'version' => '1.27.0' } }
+  let(:vcap_application) { { 'application_name' => 'GreatServiceTM' } }
+
+  it 'does not detect without otel-collector service bind' do
+    expect(component.detect).to be_nil
+  end
+
+  context 'when detected' do
+
+    before do
+      allow(services).to receive(:one_service?).with(/otel-collector/).and_return(true)
+    end
+
+    it 'detects with opentelemetry-javaagent' do
+      expect(component.detect).to eq("opentelemetry-javaagent=#{version}")
+    end
+
+    it 'downloads the opentelemetry javaagent jar', cache_fixture: 'stub-download.jar' do
+
+      component.compile
+
+      expect(sandbox + "opentelemetry_javaagent-#{version}.jar").to exist
+    end
+
+    it 'updates JAVA_OPTS' do
+      component.release
+
+      expect(java_opts).to include(
+        "-javaagent:$PWD/.java-buildpack/opentelemetry_javaagent/opentelemetry_javaagent-#{version}.jar"
+      )
+    end
+
+    it 'sets the service name from the application name' do
+      component.release
+
+      expect(java_opts).to include('-Dotel.service.name=GreatServiceTM')
+    end
+
+  end
+
+end