google-cloud-logging-logback: Allow user to specify custom LoggingOptions

google-cloud-clients/google-cloud-contrib/google-cloud-logging-logback/README.md

@@ -50,6 +50,8 @@ See [Logback filters](https://logback.qos.ch/manual/filters.html#thresholdFilter
       <level>INFO</level>
     </filter>
     <log>application.log</log> <!-- Optional : default java.log -->
+    <!-- Optional : will use the default credentials of the environment if this property is not set -->
+    <credentialsFile>/path/to/credentials.json</credentialsFile>
     <enhancer>com.example.enhancers.TestLoggingEnhancer</enhancer> <!-- Optional -->
     <enhancer>com.example.enhancers.AnotherEnhancer</enhancer> <!-- Optional -->
     <flushLevel>WARN</flushLevel> <!-- Optional : default ERROR -->
@@ -88,6 +90,7 @@ Authentication
 See the [Authentication](https://github.com/googleapis/google-cloud-java#authentication)
 section in the base directory's README.
 
+You can also specify custom credentials by setting the optional property credentialsFile in your configuration file.
 
 Limitations
 -----------

google-cloud-clients/google-cloud-contrib/google-cloud-logging-logback/src/main/java/com/google/cloud/logging/logback/LoggingAppender.java

@@ -23,6 +23,7 @@
 import ch.qos.logback.core.UnsynchronizedAppenderBase;
 import ch.qos.logback.core.util.Loader;
 import com.google.api.core.InternalApi;
+import com.google.auth.oauth2.GoogleCredentials;
 import com.google.cloud.MonitoredResource;
 import com.google.cloud.logging.LogEntry;
 import com.google.cloud.logging.Logging;
@@ -32,6 +33,9 @@
 import com.google.cloud.logging.MonitoredResourceUtil;
 import com.google.cloud.logging.Payload;
 import com.google.cloud.logging.Severity;
+import com.google.common.base.Strings;
+import java.io.FileInputStream;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashSet;
@@ -55,6 +59,8 @@
  *       Standard, GCE and GKE, defaults to "global". See <a
  *       href="https://cloud.google.com/logging/docs/api/v2/resource-list">supported resource
  *       types</a>
+ *   <li>&lt;credentialsFile&gt;/path/to/credentials/file&lt;/credentialsFile&gt; (Optional,
+ *       defaults to the default credentials of the environment)
  *   <li>(Optional) add custom labels to log entries using {@link LoggingEnhancer} classes.
  *   <li>&lt;enhancer&gt;com.example.enhancer1&lt;/enhancer&gt;
  *   <li>&lt;enhancer&gt;com.example.enhancer2&lt;/enhancer&gt;
@@ -67,13 +73,15 @@ public class LoggingAppender extends UnsynchronizedAppenderBase<ILoggingEvent> {
   private static final String LEVEL_VALUE_KEY = "levelValue";
 
   private volatile Logging logging;
+  private LoggingOptions loggingOptions;
   private List<LoggingEnhancer> loggingEnhancers;
   private List<LoggingEventEnhancer> loggingEventEnhancers;
   private WriteOption[] defaultWriteOptions;
 
   private Level flushLevel;
   private String log;
   private String resourceType;
+  private String credentialsFile;
   private Set<String> enhancerClassNames = new HashSet<>();
   private Set<String> loggingEventEnhancerClassNames = new HashSet<>();
 
@@ -111,6 +119,17 @@ public void setResourceType(String resourceType) {
     this.resourceType = resourceType;
   }
 
+  /**
+   * Sets the credentials file to use to create the {@link LoggingOptions}. The credentials returned
+   * by {@link GoogleCredentials#getApplicationDefault()} will be used if no custom credentials file
+   * has been set.
+   *
+   * @param credentialsFile The credentials file to use.
+   */
+  public void setCredentialsFile(String credentialsFile) {
+    this.credentialsFile = credentialsFile;
+  }
+
   /** Add extra labels using classes that implement {@link LoggingEnhancer}. */
   public void addEnhancer(String enhancerClassName) {
     this.enhancerClassNames.add(enhancerClassName);
@@ -186,7 +205,7 @@ public synchronized void start() {
   }
 
   String getProjectId() {
-    return LoggingOptions.getDefaultInstance().getProjectId();
+    return getLoggingOptions().getProjectId();
   }
 
   @Override
@@ -212,13 +231,37 @@ Logging getLogging() {
     if (logging == null) {
       synchronized (this) {
         if (logging == null) {
-          logging = LoggingOptions.getDefaultInstance().getService();
+          logging = getLoggingOptions().getService();
         }
       }
     }
     return logging;
   }
 
+  /** Gets the {@link LoggingOptions} to use for this {@link LoggingAppender}. */
+  LoggingOptions getLoggingOptions() {
+    if (loggingOptions == null) {
+      if (Strings.isNullOrEmpty(credentialsFile)) {
+        loggingOptions = LoggingOptions.getDefaultInstance();
+      } else {
+        try {
+          loggingOptions =
+              LoggingOptions.newBuilder()
+                  .setCredentials(
+                      GoogleCredentials.fromStream(new FileInputStream(credentialsFile)))
+                  .build();
+        } catch (IOException e) {
+          throw new RuntimeException(
+              String.format(
+                  "Could not read credentials file %s. Please verify that the file exists and is a valid Google credentials file.",
+                  credentialsFile),
+              e);
+        }
+      }
+    }
+    return loggingOptions;
+  }
+
   private LogEntry logEntryFor(ILoggingEvent e) {
     StringBuilder payload = new StringBuilder(e.getFormattedMessage()).append('\n');
     writeStack(e.getThrowableProxy(), "", payload);

google-cloud-clients/google-cloud-contrib/google-cloud-logging-logback/src/test/java/com/google/cloud/logging/logback/LoggingAppenderTest.java

@@ -22,6 +22,7 @@
 import static org.easymock.EasyMock.expectLastCall;
 import static org.easymock.EasyMock.replay;
 import static org.easymock.EasyMock.verify;
+import static org.junit.Assert.fail;
 
 import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.filter.ThresholdFilter;
@@ -31,6 +32,7 @@
 import com.google.cloud.logging.LogEntry;
 import com.google.cloud.logging.Logging;
 import com.google.cloud.logging.Logging.WriteOption;
+import com.google.cloud.logging.LoggingOptions;
 import com.google.cloud.logging.Payload.StringPayload;
 import com.google.cloud.logging.Severity;
 import com.google.common.collect.ImmutableMap;
@@ -211,6 +213,32 @@ public void testMdcValuesAreConvertedToLabels() {
     assertThat(capturedArgument.getValue().iterator().next()).isEqualTo(logEntry);
   }
 
+  @Test
+  public void testCreateLoggingOptions() {
+    // Try to build LoggingOptions with custom credentials.
+    final String nonExistentFile = "/path/to/non/existent/file";
+    LoggingAppender appender = new LoggingAppender();
+    appender.setCredentialsFile(nonExistentFile);
+    try {
+      appender.getLoggingOptions();
+      fail("Expected exception");
+    } catch (Exception e) {
+      assertThat(e.getMessage().contains(nonExistentFile));
+    }
+    // Try to build LoggingOptions with default credentials.
+    LoggingOptions defaultOptions = null;
+    try {
+      defaultOptions = LoggingOptions.getDefaultInstance();
+    } catch (Exception e) {
+      // Could not build a default LoggingOptions instance.
+    }
+    if (defaultOptions != null) {
+      appender = new LoggingAppender();
+      LoggingOptions options = appender.getLoggingOptions();
+      assertThat(options).isEqualTo(defaultOptions);
+    }
+  }
+
   private LoggingEvent createLoggingEvent(Level level, long timestamp) {
     LoggingEvent loggingEvent = new LoggingEvent();
     loggingEvent.setMessage("this is a test");