feat: configure opt-out metada auto-population for JUL handler (#807)

Adds metadata auto-population flag to JUL handler.
Adds metadata auto-population flag to logging config file.
Forwards metadata auto-population flag via WriteOption to write() calls.
Refactors JUL handler tests to remove duplication, unused calls and warnings

Author: minherz

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

@@ -41,6 +41,7 @@ class LoggingConfig {
   private static final String RESOURCE_TYPE_TAG = "resourceType";
   private static final String ENHANCERS_TAG = "enhancers";
   private static final String USE_INHERITED_CONTEXT = "useInheritedContext";
+  private static final String AUTO_POPULATE_METADATA = "autoPopulateMetadata";
 
   public LoggingConfig(String className) {
     this.className = className;
@@ -76,6 +77,14 @@ Formatter getFormatter() {
     return getFormatterProperty(FORMATTER_TAG, new SimpleFormatter());
   }
 
+  Boolean getAutoPopulateMetadata() {
+    String flag = getProperty(AUTO_POPULATE_METADATA);
+    if (flag != null) {
+      return Boolean.parseBoolean(flag);
+    }
+    return null;
+  }
+
   MonitoredResource getMonitoredResource(String projectId) {
     String resourceType = getProperty(RESOURCE_TYPE_TAG, "");
     return MonitoredResourceUtil.getResource(projectId, resourceType);

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

@@ -17,6 +17,7 @@
 package com.google.cloud.logging;
 
 import static com.google.common.base.MoreObjects.firstNonNull;
+import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.cloud.MonitoredResource;
 import com.google.cloud.logging.Logging.WriteOption;
@@ -25,6 +26,7 @@
 import com.google.common.collect.Iterables;
 import java.time.Instant;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.LinkedList;
 import java.util.List;
@@ -109,6 +111,9 @@
  *       else "global").
  *   <li>{@code com.google.cloud.logging.Synchronicity} the synchronicity of the write method to use
  *       to write logs to the Cloud Logging service (defaults to {@link Synchronicity#ASYNC}).
+ *   <li>{@code com.google.cloud.logging.LoggingHandler.autoPopulateMetadata} is a boolean flag that
+ *       opts-out the population of the log entries metadata before the logs are sent to Cloud
+ *       Logging (defaults to {@code true}).
  * </ul>
  *
  * <p>To add a {@code LoggingHandler} to an existing {@link Logger} and be sure to avoid infinite
@@ -139,6 +144,8 @@ public class LoggingHandler extends Handler {
 
   private volatile Level flushLevel;
 
+  private volatile Boolean autoPopulateMetadata;
+
   private WriteOption[] defaultWriteOptions;
 
   /** Creates an handler that publishes messages to Cloud Logging. */
@@ -196,7 +203,10 @@ public LoggingHandler(
   }
 
   /**
-   * Creates a handler that publishes messages to Cloud Logging.
+   * Creates a handler that publishes messages to Cloud Logging. Auto-population of the logs
+   * metadata can be opted-out in {@code options} argument or in the configuration file. At least
+   * one flag {@link LoggingOptions} or {@link LoggingConfig} has to be explicitly set to {@code
+   * false} in order to opt-out the metadata auto-population.
    *
    * @param log the name of the log to which log entries are written
    * @param options options for the Cloud Logging service
@@ -222,14 +232,18 @@ public LoggingHandler(
       setLevel(level);
       baseLevel = level.equals(Level.ALL) ? Level.FINEST : level;
       flushLevel = config.getFlushLevel();
+      Boolean f1 = options.getAutoPopulateMetadata();
+      Boolean f2 = config.getAutoPopulateMetadata();
+      autoPopulateMetadata = isTrueOrNull(f1) && isTrueOrNull(f2);
       String logName = log != null ? log : config.getLogName();
-
       MonitoredResource resource =
           firstNonNull(
               monitoredResource, config.getMonitoredResource(loggingOptions.getProjectId()));
       List<WriteOption> writeOptions = new ArrayList<WriteOption>();
       writeOptions.add(WriteOption.logName(logName));
-      writeOptions.add(WriteOption.resource(resource));
+      if (resource != null) {
+        writeOptions.add(WriteOption.resource(resource));
+      }
       writeOptions.add(
           WriteOption.labels(
               ImmutableMap.of(
@@ -240,6 +254,7 @@ public LoggingHandler(
       if (destination != null) {
         writeOptions.add(WriteOption.destination(destination));
       }
+      writeOptions.add(WriteOption.autoPopulateMetadata(autoPopulateMetadata));
       defaultWriteOptions = Iterables.toArray(writeOptions, WriteOption.class);
 
       getLogging().setFlushSeverity(severityFor(flushLevel));
@@ -365,6 +380,28 @@ public Synchronicity getSynchronicity() {
     return getLogging().getWriteSynchronicity();
   }
 
+  /**
+   * Sets the metadata auto population flag.
+   */
+  public void setAutoPopulateMetadata(Boolean value) {
+    checkNotNull(value);
+    this.autoPopulateMetadata = value;
+    List<WriteOption> writeOptions = Arrays.asList(defaultWriteOptions);
+    for (int i = 0; i < writeOptions.size(); i++) {
+      if (writeOptions.get(i).getOptionType() == WriteOption.OptionType.AUTO_POPULATE_METADATA) {
+        writeOptions.remove(i);
+        break;
+      }
+    }
+    writeOptions.add(WriteOption.autoPopulateMetadata(value));
+    defaultWriteOptions = Iterables.toArray(writeOptions, WriteOption.class);
+  }
+
+  /** Gets the metadata auto population flag. */
+  public Boolean getAutoPopulateMetadata() {
+    return this.autoPopulateMetadata;
+  }
+
   /**
    * Adds the provided {@code LoggingHandler} to {@code logger}. Use this method to register Cloud
    * Logging handlers instead of {@link Logger#addHandler(Handler)} to avoid infinite recursion when
@@ -417,4 +454,8 @@ private Logging getLogging() {
     }
     return logging;
   }
+
+  private static boolean isTrueOrNull(Boolean b) {
+    return b == null || b == Boolean.TRUE;
+  }
 }