Third-party exporter loading framework (#159)

agent-bootstrap/src/main/java/io/opentelemetry/auto/config/Config.java

@@ -37,6 +37,7 @@ public class Config {
   private static final Pattern ENV_REPLACEMENT = Pattern.compile("[^a-zA-Z0-9_]");
 
   public static final String EXPORTER = "exporter";
+  public static final String EXPORTER_JAR = "exporter.jar";
   public static final String SERVICE = "service";
   public static final String CONFIGURATION_FILE = "trace.config";
   public static final String TRACE_ENABLED = "trace.enabled";
@@ -83,6 +84,7 @@ public class Config {
   private static final String DEFAULT_TRACE_METHODS = null;
 
   @Getter private final String exporter;
+  @Getter private final String exporterJar;
   @Getter private final String serviceName;
   @Getter private final boolean traceEnabled;
   @Getter private final boolean integrationsEnabled;
@@ -114,6 +116,7 @@ public class Config {
     propertiesFromConfigFile = loadConfigurationFile();
 
     exporter = getSettingFromEnvironment(EXPORTER, null);
+    exporterJar = getSettingFromEnvironment(EXPORTER_JAR, null);
     serviceName = getSettingFromEnvironment(SERVICE, "(unknown)");
     traceEnabled = getBooleanSettingFromEnvironment(TRACE_ENABLED, DEFAULT_TRACE_ENABLED);
     integrationsEnabled =
@@ -170,6 +173,7 @@ public class Config {
   // Read order: Properties -> Parent
   private Config(final Properties properties, final Config parent) {
     exporter = properties.getProperty(EXPORTER, parent.exporter);
+    exporterJar = properties.getProperty(EXPORTER_JAR, parent.exporterJar);
     serviceName = properties.getProperty(SERVICE, parent.serviceName);
 
     traceEnabled = getPropertyBooleanValue(properties, TRACE_ENABLED, parent.traceEnabled);

agent-tooling/agent-tooling.gradle

@@ -23,6 +23,9 @@ dependencies {
   compile deps.opentelemetrySdk
   compileOnly deps.opentelemetryJaeger
 
+  // TODO: This might have to live in opentelemetry-java
+  compile project(':exporter-support')
+
   // Needed for Jaeger exporter
   compileOnly group: 'io.grpc', name: 'grpc-api', version: '1.24.0'
 
@@ -33,6 +36,7 @@ dependencies {
   implementation deps.autoservice
 
   testCompile project(':testing')
+  testCompile project(':dummy-exporter')
 
   instrumentationMuzzle sourceSets.main.output
   instrumentationMuzzle configurations.compile

agent-tooling/src/main/java/io/opentelemetry/auto/tooling/DefaultConfigProvider.java

@@ -0,0 +1,53 @@
+package io.opentelemetry.auto.tooling;
+
+import io.opentelemetry.auto.config.Config;
+import io.opentelemetry.auto.exportersupport.ConfigProvider;
+
+public class DefaultConfigProvider implements ConfigProvider {
+  private final String prefix;
+
+  public DefaultConfigProvider(final String prefix) {
+    this.prefix = prefix;
+  }
+
+  @Override
+  public String getString(final String key, final String defaultValue) {
+    return Config.getSettingFromEnvironment(prefix + "." + key, defaultValue);
+  }
+
+  @Override
+  public int getInt(final String key, final int defaultValue) {
+    final String s = Config.getSettingFromEnvironment(prefix + "." + key, null);
+    if (s == null) {
+      return defaultValue;
+    }
+    return Integer.parseInt(s); // TODO: Handle format errors gracefully?
+  }
+
+  @Override
+  public long getLong(final String key, final long defaultValue) {
+    final String s = Config.getSettingFromEnvironment(prefix + "." + key, null);
+    if (s == null) {
+      return defaultValue;
+    }
+    return Long.parseLong(s); // TODO: Handle format errors gracefully?
+  }
+
+  @Override
+  public boolean getBoolean(final String key, final boolean defaultValue) {
+    final String s = Config.getSettingFromEnvironment(prefix + "." + key, null);
+    if (s == null) {
+      return defaultValue;
+    }
+    return Boolean.parseBoolean(s); // TODO: Handle format errors gracefully?
+  }
+
+  @Override
+  public double getDouble(final String key, final double defaultValue) {
+    final String s = Config.getSettingFromEnvironment(prefix + "." + key, null);
+    if (s == null) {
+      return defaultValue;
+    }
+    return Double.parseDouble(s); // TODO: Handle format errors gracefully?
+  }
+}

agent-tooling/src/main/java/io/opentelemetry/auto/tooling/ExporterClassLoader.java

@@ -0,0 +1,54 @@
+package io.opentelemetry.auto.tooling;
+
+import static io.opentelemetry.auto.tooling.ShadingRemapper.rule;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.net.URLClassLoader;
+import net.bytebuddy.jar.asm.ClassReader;
+import net.bytebuddy.jar.asm.ClassWriter;
+import net.bytebuddy.jar.asm.commons.ClassRemapper;
+
+public class ExporterClassLoader extends URLClassLoader {
+  // We need to prefix the names to prevent the gradle shadowJar relocation rules from touching
+  // them. It's possible to do this by excluding this class from shading, but it may cause issue
+  // with transitive dependencies down the line.
+  private final ShadingRemapper remapper =
+      new ShadingRemapper(
+          rule(
+              "#io.opentelemetry.OpenTelemetry",
+              "#io.opentelemetry.auto.shaded.io.opentelemetry.OpenTelemetry"),
+          rule(
+              "#io.opentelemetry.context",
+              "#io.opentelemetry.auto.shaded.io.opentelemetry.context"),
+          rule(
+              "#io.opentelemetry.distributedcontext",
+              "#io.opentelemetry.auto.shaded.io.opentelemetry.distributedcontext"),
+          rule(
+              "#io.opentelemetry.internal",
+              "#io.opentelemetry.auto.shaded.io.opentelemetry.internal"),
+          rule(
+              "#io.opentelemetry.metrics",
+              "#io.opentelemetry.auto.shaded.io.opentelemetry.metrics"),
+          rule("#io.opentelemetry.trace", "#io.opentelemetry.auto.shaded.io.opentelemetry.trace"));
+
+  public ExporterClassLoader(final URL[] urls, final ClassLoader parent) {
+    super(urls, parent);
+  }
+
+  @Override
+  protected Class<?> findClass(final String name) throws ClassNotFoundException {
+
+    // Use resource loading to get the class as a stream of bytes, then use ASM to transform it.
+    try (final InputStream in = getResourceAsStream(name.replace('.', '/') + ".class")) {
+      final ClassWriter cw = new ClassWriter(0);
+      final ClassReader cr = new ClassReader(in);
+      cr.accept(new ClassRemapper(cw, remapper), ClassReader.EXPAND_FRAMES);
+      final byte[] bytes = cw.toByteArray();
+      return defineClass(name, bytes, 0, bytes.length);
+    } catch (final IOException e) {
+      throw new ClassNotFoundException(name);
+    }
+  }
+}

agent-tooling/src/main/java/io/opentelemetry/auto/tooling/ShadingRemapper.java

@@ -0,0 +1,45 @@
+package io.opentelemetry.auto.tooling;
+
+import java.util.Map;
+import java.util.TreeMap;
+import net.bytebuddy.jar.asm.commons.Remapper;
+
+public class ShadingRemapper extends Remapper {
+  public static class Rule {
+    private final String from;
+    private final String to;
+
+    public Rule(String from, String to) {
+      // Strip prefix added to prevent the build-time relocation from changing the names
+      if (from.startsWith("#")) {
+        from = from.substring(1);
+      }
+      if (to.startsWith("#")) {
+        to = to.substring(1);
+      }
+      this.from = from.replace('.', '/');
+      this.to = to.replace('.', '/');
+    }
+  }
+
+  public static Rule rule(final String from, final String to) {
+    return new Rule(from, to);
+  }
+
+  private final TreeMap<String, String> map = new TreeMap<>();
+
+  public ShadingRemapper(final Rule... rules) {
+    for (final Rule rule : rules) {
+      map.put(rule.from, rule.to);
+    }
+  }
+
+  @Override
+  public String map(final String internalName) {
+    final Map.Entry<String, String> e = map.floorEntry(internalName);
+    if (e != null && internalName.startsWith(e.getKey())) {
+      return e.getValue() + internalName.substring(e.getKey().length());
+    }
+    return super.map(internalName);
+  }
+}

agent-tooling/src/main/java/io/opentelemetry/auto/tooling/TracerInstaller.java

@@ -1,39 +1,83 @@
 package io.opentelemetry.auto.tooling;
 
+import com.google.common.annotations.VisibleForTesting;
 import io.opentelemetry.auto.config.Config;
+import io.opentelemetry.auto.exportersupport.SpanExporterFactory;
 import io.opentelemetry.auto.tooling.exporter.ExporterConfigException;
 import io.opentelemetry.auto.tooling.exporter.ExporterRegistry;
-import io.opentelemetry.auto.tooling.exporter.SpanExporterFactory;
 import io.opentelemetry.sdk.OpenTelemetrySdk;
 import io.opentelemetry.sdk.trace.export.SimpleSpansProcessor;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.Iterator;
+import java.util.ServiceLoader;
 import lombok.extern.slf4j.Slf4j;
 
 @Slf4j
 public class TracerInstaller {
-
   /** Register agent tracer if no agent tracer is already registered. */
   public static synchronized void installAgentTracer() {
     if (Config.get().isTraceEnabled()) {
 
       // Try to create an exporter
-      final String exporter = Config.get().getExporter();
-      if (exporter != null) {
+      SpanExporter exporter = null;
+      final String expName = Config.get().getExporter();
+      if (expName != null) {
         try {
-          final SpanExporterFactory f = ExporterRegistry.getInstance().getFactory(exporter);
-          OpenTelemetrySdk.getTracerFactory()
-              .addSpanProcessor(SimpleSpansProcessor.newBuilder(f.newExporter()).build());
-          log.info("Loaded span exporter: " + exporter);
+          final io.opentelemetry.auto.tooling.exporter.SpanExporterFactory f =
+              ExporterRegistry.getInstance().getFactory(expName);
+          exporter = f.newExporter();
+          log.info("Loaded span exporter: " + expName);
         } catch (final ExporterConfigException e) {
           log.warn("Error loading exporter. Spans will be dropped", e);
         }
+      } else {
+        final String exporterJar = Config.get().getExporterJar();
+        if (exporterJar != null) {
+          exporter = loadFromJar(exporterJar);
+        }
+      }
+      if (exporter != null) {
+        OpenTelemetrySdk.getTracerFactory()
+            .addSpanProcessor(SimpleSpansProcessor.newBuilder(exporter).build());
+        log.info("Installed span exporter: " + exporter.getClass().getCanonicalName());
       } else {
         log.warn("No exporter is specified. Tracing will run but spans are dropped");
       }
     } else {
-      log.debug("Tracing is disabled.");
+      log.info("Tracing is disabled.");
     }
   }
 
+  @VisibleForTesting
+  private static synchronized SpanExporter loadFromJar(final String exporterJar) {
+    final URL url;
+    try {
+      url = new File(exporterJar).toURI().toURL();
+    } catch (final MalformedURLException e) {
+      log.warn("Filename could not be parsed: " + exporterJar + ". Exporter is not installed");
+      return null;
+    }
+
+    final ExporterClassLoader exporterLoader =
+        new ExporterClassLoader(new URL[] {url}, TracerInstaller.class.getClassLoader());
+    final ServiceLoader<SpanExporterFactory> sl =
+        ServiceLoader.load(SpanExporterFactory.class, exporterLoader);
+    final Iterator<SpanExporterFactory> itor = sl.iterator();
+    if (itor.hasNext()) {
+      final SpanExporterFactory f = itor.next();
+      if (itor.hasNext()) {
+        log.warn(
+            "Exporter JAR defines more than one factory. Only the first one found will be used");
+      }
+      return f.fromConfig(new DefaultConfigProvider("exporter"));
+    }
+    log.warn("No matching providers in jar " + exporterJar);
+    return null;
+  }
+
   public static void logVersionInfo() {
     VersionLogger.logAllVersions();
     log.debug(

agent-tooling/src/test/groovy/io/opentelemetry/auto/tooling/ExporterLoaderTest.groovy

@@ -0,0 +1,18 @@
+package io.opentelemetry.auto.tooling
+
+
+import io.opentelemetry.auto.util.test.AgentSpecification
+import io.opentelemetry.sdk.OpenTelemetrySdk
+
+class ExporterLoaderTest extends AgentSpecification {
+  def jarName = "../dummy-exporter/build/libs/dummy-exporter-0.1.0-all.jar"
+  def tracer = OpenTelemetrySdk.getTracerFactory().get("test")
+
+  def "test load exporter"() {
+    when:
+    def exporter = TracerInstaller.loadFromJar(jarName)
+
+    then:
+    exporter.getClass().getName() == "io.opentelemetry.auto.dummyexporter.DummyExporter"
+  }
+}

dummy-exporter/dummy-exporter.gradle

@@ -0,0 +1,14 @@
+plugins {
+  id "com.github.johnrengelman.shadow"
+}
+
+apply from: "${rootDir}/gradle/java.gradle"
+
+dependencies {
+  compileOnly deps.opentelemetrySdk
+  compileOnly deps.opentelemetryApi
+  compile project(":exporter-support")
+}
+
+
+

dummy-exporter/src/main/java/io/opentelemetry/auto/dummyexporter/DummyExporter.java

@@ -0,0 +1,47 @@
+package io.opentelemetry.auto.dummyexporter;
+
+import io.opentelemetry.sdk.trace.SpanData;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import io.opentelemetry.trace.AttributeValue;
+import java.util.List;
+import java.util.Map;
+
+public class DummyExporter implements SpanExporter {
+  private final String prefix;
+
+  public DummyExporter(final String prefix) {
+    this.prefix = prefix;
+  }
+
+  @Override
+  public ResultCode export(final List<SpanData> list) {
+    for (final SpanData span : list) {
+      System.out.print(
+          prefix + " " + span.getName() + " " + span.getSpanId().toLowerBase16() + " ");
+      for (final Map.Entry<String, AttributeValue> attr : span.getAttributes().entrySet()) {
+        System.out.print(attr.getKey() + "=");
+        final AttributeValue value = attr.getValue();
+        switch (value.getType()) {
+          case STRING:
+            System.out.print('"' + value.getStringValue() + '"');
+            break;
+          case BOOLEAN:
+            System.out.print(value.getBooleanValue());
+            break;
+          case LONG:
+            System.out.print(value.getLongValue());
+            break;
+          case DOUBLE:
+            System.out.print(value.getDoubleValue());
+            break;
+        }
+        System.out.print(" ");
+      }
+    }
+    System.out.println();
+    return ResultCode.SUCCESS;
+  }
+
+  @Override
+  public void shutdown() {}
+}

dummy-exporter/src/main/java/io/opentelemetry/auto/dummyexporter/DummySpanExporterFactory.java

@@ -0,0 +1,12 @@
+package io.opentelemetry.auto.dummyexporter;
+
+import io.opentelemetry.auto.exportersupport.ConfigProvider;
+import io.opentelemetry.auto.exportersupport.SpanExporterFactory;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+
+public class DummySpanExporterFactory implements SpanExporterFactory {
+  @Override
+  public SpanExporter fromConfig(final ConfigProvider config) {
+    return new DummyExporter(config.getString("prefix", "no-prefix"));
+  }
+}

dummy-exporter/src/main/resources/META-INF/services/io.opentelemetry.auto.exportersupport.SpanExporterFactory

@@ -0,0 +1 @@
+io.opentelemetry.auto.dummyexporter.DummySpanExporterFactory

exporter-support/exporter-support.gradle

@@ -0,0 +1,5 @@
+apply from: "${rootDir}/gradle/java.gradle"
+
+dependencies {
+  compileOnly deps.opentelemetrySdk
+}

exporter-support/src/main/java/io/opentelemetry/auto/exportersupport/ConfigProvider.java

@@ -0,0 +1,13 @@
+package io.opentelemetry.auto.exportersupport;
+
+public interface ConfigProvider {
+  String getString(String key, String defaultValue);
+
+  int getInt(String key, int defaultValue);
+
+  long getLong(String key, long defaultValue);
+
+  boolean getBoolean(String key, boolean defaultValue);
+
+  double getDouble(String key, double defaultValue);
+}

exporter-support/src/main/java/io/opentelemetry/auto/exportersupport/SpanExporterFactory.java

@@ -0,0 +1,7 @@
+package io.opentelemetry.auto.exportersupport;
+
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+
+public interface SpanExporterFactory {
+  SpanExporter fromConfig(ConfigProvider config);
+}

settings.gradle

@@ -25,6 +25,10 @@ include ':agent-bootstrap'
 include ':agent-tooling'
 include ':load-generator'
 
+// exporter support
+include ':exporter-support'
+
+// misc
 include ':testing'
 include ':utils:test-utils'
 include ':utils:thread-utils'
@@ -133,6 +137,9 @@ include ':benchmark-integration'
 include ':benchmark-integration:jetty-perftest'
 include ':benchmark-integration:play-perftest'
 
+//Dummy exporter TODO: Move it somewhere better
+include ":dummy-exporter"
+
 def setBuildFile(project) {
   project.buildFileName = "${project.name}.gradle"
   project.children.each {
@@ -145,3 +152,4 @@ setBuildFile(rootProject)
 project(':agent-bootstrap').name = 'auto-bootstrap'
 project(':agent-tooling').name = 'auto-tooling'
 project(':java-agent').name = 'opentelemetry-auto'
+