feat(logging): OpenTelemetry trace/span ID integration for Java logging library

README.md

@@ -52,7 +52,7 @@ If you are using Maven without the BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies:
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:26.39.0')
+implementation platform('com.google.cloud:libraries-bom:26.40.0')
 
 implementation 'com.google.cloud:google-cloud-logging'
 ```

google-cloud-logging/pom.xml

@@ -17,6 +17,14 @@
     <site.installationModule>google-cloud-logging</site.installationModule>
   </properties>
   <dependencies>
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-api</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-context</artifactId>
+    </dependency>
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
@@ -133,6 +141,23 @@
       <artifactId>grpc-google-cloud-logging-v2</artifactId>
       <scope>test</scope>
     </dependency>
+    <!-- OpenTelemetry -->
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-sdk</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-sdk-testing</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>io.opentelemetry</groupId>
+      <artifactId>opentelemetry-sdk-trace</artifactId>
+      <scope>test</scope>
+    </dependency>
+    <!-- END OpenTelemetry -->
     <!-- Need testing utility classes for generated gRPC clients tests -->
     <dependency>
       <groupId>com.google.api</groupId>

google-cloud-logging/src/main/java/com/google/cloud/logging/Context.java

@@ -22,6 +22,8 @@
 import com.google.common.base.Splitter;
 import com.google.common.collect.Iterables;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
+import io.opentelemetry.api.trace.Span;
+import io.opentelemetry.api.trace.SpanContext;
 import java.util.List;
 import java.util.Objects;
 import java.util.regex.Matcher;
@@ -34,22 +36,27 @@ public class Context {
   private static final Pattern W3C_TRACE_CONTEXT_FORMAT =
       Pattern.compile(
           "^00-(?!00000000000000000000000000000000)[0-9a-f]{32}-(?!0000000000000000)[0-9a-f]{16}-[0-9a-f]{2}$");
+  // Trace sampled flag for bit masking
+  // see https://www.w3.org/TR/trace-context/#trace-flags for details
+  private static final byte FLAG_SAMPLED = 1; // 00000001
   private final HttpRequest request;
   private final String traceId;
   private final String spanId;
-
+  private final boolean traceSampled;
   /** A builder for {@see Context} objects. */
   public static final class Builder {
     private HttpRequest.Builder requestBuilder = HttpRequest.newBuilder();
     private String traceId;
     private String spanId;
+    private boolean traceSampled;
 
     Builder() {}
 
     Builder(Context context) {
       this.requestBuilder = context.request.toBuilder();
       this.traceId = context.traceId;
       this.spanId = context.spanId;
+      this.traceSampled = context.traceSampled;
     }
 
     /** Sets the HTTP request. */
@@ -118,17 +125,28 @@ public Builder setSpanId(String spanId) {
       return this;
     }
 
+    /** Sets the boolean as trace sampled flag. */
+    @CanIgnoreReturnValue
+    public Builder setTraceSampled(boolean traceSampled) {
+      this.traceSampled = traceSampled;
+      return this;
+    }
+
     /**
-     * Sets the trace id and span id values by parsing the string which represents xCloud Trace
-     * Context. The Cloud Trace Context is passed as {@code x-cloud-trace-context} header (can be in
-     * Pascal case format). The string format is <code>TRACE_ID/SPAN_ID;o=TRACE_TRUE</code>.
+     * Sets the trace id, span id and trace sampled flag values by parsing the string which
+     * represents xCloud Trace Context. The Cloud Trace Context is passed as {@code
+     * x-cloud-trace-context} header (can be in Pascal case format). The string format is <code>
+     * TRACE_ID/SPAN_ID;o=TRACE_TRUE</code>.
      *
      * @see <a href="https://cloud.google.com/trace/docs/setup#force-trace">Cloud Trace header
      *     format.</a>
      */
     @CanIgnoreReturnValue
     public Builder loadCloudTraceContext(String cloudTrace) {
       if (cloudTrace != null) {
+        if (cloudTrace.indexOf("o=") >= 0) {
+          setTraceSampled(Iterables.get(Splitter.on("o=").split(cloudTrace), 1).equals("1"));
+        }
         cloudTrace = Iterables.get(Splitter.on(';').split(cloudTrace), 0);
         int split = cloudTrace.indexOf('/');
         if (split >= 0) {
@@ -149,10 +167,11 @@ public Builder loadCloudTraceContext(String cloudTrace) {
     }
 
     /**
-     * Sets the trace id and span id values by parsing the string which represents the standard W3C
-     * trace context propagation header. The context propagation header is passed as {@code
-     * traceparent} header. The method currently supports ONLY version {@code "00"}. The string
-     * format is <code>00-TRACE_ID-SPAN_ID-FLAGS</code>. field of the {@code version-format} value.
+     * Sets the trace id, span id and trace sampled flag values by parsing the string which
+     * represents the standard W3C trace context propagation header. The context propagation header
+     * is passed as {@code traceparent} header. The method currently supports ONLY version {@code
+     * "00"}. The string format is <code>00-TRACE_ID-SPAN_ID-FLAGS</code>. field of the {@code
+     * version-format} value.
      *
      * @see <a href=
      *     "https://www.w3.org/TR/trace-context/#traceparent-header-field-values">traceparent header
@@ -171,7 +190,27 @@ public Builder loadW3CTraceParentContext(String traceParent) {
         List<String> fields = Splitter.on('-').splitToList(traceParent);
         setTraceId(fields.get(1));
         setSpanId(fields.get(2));
-        // fields[3] contains flag(s)
+        boolean sampled = (Integer.parseInt(fields.get(3), 16) & FLAG_SAMPLED) == FLAG_SAMPLED;
+        setTraceSampled(sampled);
+      }
+      return this;
+    }
+
+    /**
+     * Sets the trace id, span id and trace sampled flag values by parsing detected OpenTelemetry
+     * span context.
+     *
+     * @see <a href="https://opentelemetry.io/docs/specs/otel/trace/api/#spancontext">OpenTelemetry
+     *     SpanContext.</a>
+     */
+    @CanIgnoreReturnValue
+    public Builder loadOpenTelemetryContext() {
+      io.opentelemetry.context.Context currentContext = io.opentelemetry.context.Context.current();
+      SpanContext spanContext = Span.fromContext(currentContext).getSpanContext();
+      if (spanContext != null && spanContext.isValid()) {
+        setTraceId(spanContext.getTraceId());
+        setSpanId(spanContext.getSpanId());
+        setTraceSampled(spanContext.isSampled());
       }
       return this;
     }
@@ -191,6 +230,7 @@ public Context build() {
     }
     this.traceId = builder.traceId;
     this.spanId = builder.spanId;
+    this.traceSampled = builder.traceSampled;
   }
 
   public HttpRequest getHttpRequest() {
@@ -205,6 +245,10 @@ public String getSpanId() {
     return this.spanId;
   }
 
+  public boolean getTraceSampled() {
+    return this.traceSampled;
+  }
+
   @Override
   public int hashCode() {
     return Objects.hash(request, traceId, spanId);
@@ -216,6 +260,7 @@ public String toString() {
         .add("request", request)
         .add("traceId", traceId)
         .add("spanId", spanId)
+        .add("traceSampled", traceSampled)
         .toString();
   }
 
@@ -230,7 +275,8 @@ public boolean equals(Object obj) {
     Context other = (Context) obj;
     return Objects.equals(request, other.request)
         && Objects.equals(traceId, other.traceId)
-        && Objects.equals(spanId, other.spanId);
+        && Objects.equals(spanId, other.spanId)
+        && Objects.equals(traceSampled, other.traceSampled);
   }
 
   /** Returns a builder for this object. */

google-cloud-logging/src/main/java/com/google/cloud/logging/ContextHandler.java

@@ -18,7 +18,17 @@
 
 /** Class provides a per-thread storage of the {@see Context} instances. */
 public class ContextHandler {
+
+  public enum ContextPriority {
+    NO_INPUT,
+    XCLOUD_HEADER,
+    W3C_HEADER,
+    OTEL_EXTRACTED
+  }
+
   private static final ThreadLocal<Context> contextHolder = initContextHolder();
+  private static final ThreadLocal<ContextPriority> currentPriority =
+      ThreadLocal.withInitial(() -> ContextPriority.NO_INPUT);
 
   /**
    * Initializes the context holder to {@link InheritableThreadLocal} if {@link LogManager}
@@ -41,10 +51,45 @@ public Context getCurrentContext() {
   }
 
   public void setCurrentContext(Context context) {
-    contextHolder.set(context);
+    setCurrentContext(context, ContextPriority.NO_INPUT);
+  }
+
+  public ContextPriority getCurrentContextPriority() {
+    return currentPriority.get();
+  }
+
+  /**
+   * Sets the context based on the priority. Overrides traceId, spanId and TraceSampled if the
+   * passed priority is higher. HttpRequest values will be retrieved and combined from existing
+   * context if HttpRequest in the new context is empty .
+   */
+  public void setCurrentContext(Context context, ContextPriority priority) {
+    if (priority != null && priority.compareTo(currentPriority.get()) >= 0 && context != null) {
+      Context.Builder combinedContextBuilder =
+          Context.newBuilder()
+              .setTraceId(context.getTraceId())
+              .setSpanId(context.getSpanId())
+              .setTraceSampled(context.getTraceSampled());
+      Context currentContext = getCurrentContext();
+
+      if (context.getHttpRequest() != null) {
+        combinedContextBuilder.setRequest(context.getHttpRequest());
+      }
+      // Combines HttpRequest from the existing context if HttpRequest in new context is empty.
+      else if (currentContext != null && currentContext.getHttpRequest() != null) {
+        combinedContextBuilder.setRequest(currentContext.getHttpRequest());
+      }
+
+      contextHolder.set(combinedContextBuilder.build());
+      currentPriority.set(priority);
+    }
   }
 
   public void removeCurrentContext() {
     contextHolder.remove();
   }
+
+  public void removeCurrentContextPriority() {
+    currentPriority.remove();
+  }
 }

google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingHandler.java

@@ -171,7 +171,7 @@ public enum LogTarget {
 
   private final WriteOption[] defaultWriteOptions;
 
-  /** Creates an handler that publishes messages to Cloud Logging. */
+  /** Creates a handler that publishes messages to Cloud Logging. */
   public LoggingHandler() {
     this(null, null, null);
   }

google-cloud-logging/src/main/java/com/google/cloud/logging/LoggingImpl.java

@@ -41,6 +41,7 @@
 import com.google.cloud.MonitoredResourceDescriptor;
 import com.google.cloud.PageImpl;
 import com.google.cloud.Tuple;
+import com.google.cloud.logging.ContextHandler.ContextPriority;
 import com.google.cloud.logging.spi.v2.LoggingRpc;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Ascii;
@@ -89,6 +90,7 @@
 import com.google.logging.v2.WriteLogEntriesResponse;
 import com.google.protobuf.Empty;
 import com.google.protobuf.util.Durations;
+import io.opentelemetry.api.trace.Span;
 import java.text.ParseException;
 import java.util.ArrayList;
 import java.util.List;
@@ -822,7 +824,7 @@ public Iterable<LogEntry> populateMetadata(
         customResource == null
             ? MonitoredResourceUtil.getResource(getOptions().getProjectId(), null)
             : customResource;
-    final Context context = new ContextHandler().getCurrentContext();
+
     final ArrayList<LogEntry> populatedLogEntries = Lists.newArrayList();
 
     // populate empty metadata fields of log entries before calling write API
@@ -834,13 +836,23 @@ public Iterable<LogEntry> populateMetadata(
       if (resourceMetadata != null && entry.getResource() == null) {
         entityBuilder.setResource(resourceMetadata);
       }
+
+      ContextHandler contextHandler = new ContextHandler();
+      // Populate trace/span ID from OpenTelemetry span context to logging context.
+      if (Span.current().getSpanContext().isValid()) {
+        Context.Builder contextBuilder = Context.newBuilder().loadOpenTelemetryContext();
+        contextHandler.setCurrentContext(contextBuilder.build(), ContextPriority.OTEL_EXTRACTED);
+      }
+
+      Context context = contextHandler.getCurrentContext();
       if (context != null && entry.getHttpRequest() == null) {
         entityBuilder.setHttpRequest(context.getHttpRequest());
       }
       if (context != null && Strings.isNullOrEmpty(entry.getTrace())) {
         MonitoredResource resource =
             entry.getResource() != null ? entry.getResource() : resourceMetadata;
         entityBuilder.setTrace(getFormattedTrace(context.getTraceId(), resource));
+        entityBuilder.setTraceSampled(context.getTraceSampled());
       }
       if (context != null && Strings.isNullOrEmpty(entry.getSpanId())) {
         entityBuilder.setSpanId(context.getSpanId());