googleapis#3215 allow user to specify custom LoggingOptions

olavloite · Mar 23, 2019 · c4fd4da · c4fd4da
1 parent db18d86
commit c4fd4da
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diff --git a/google-cloud-clients/google-cloud-contrib/google-cloud-logging-logback/README.md b/google-cloud-clients/google-cloud-contrib/google-cloud-logging-logback/README.md
@@ -88,6 +88,23 @@ 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 and other options by creating a subclass of `com.google.cloud.logging.logback.LoggingAppender` and override the method `createLoggingOptions()`. Your logback.xml configuration file must reference your subclass instead of `com.google.cloud.logging.logback.LoggingAppender`.
+
+```java
+public class CustomLoggingAppender extends LoggingAppender {
+  @Override
+  public LoggingOptions createLoggingOptions() {
+    try {
+      return LoggingOptions.newBuilder()
+          .setCredentials(GoogleCredentials.fromStream(
+              new FileInputStream("/path/to/credentials.json")))
+          .build();
+    } catch (IOException e) {
+      throw new RuntimeException("Could not find credentials", e);
+    }
+  }
+}
+```
 
 Limitations
 -----------

diff --git a/...cloud-logging-logback/src/main/java/com/google/cloud/logging/logback/LoggingAppender.java b/...cloud-logging-logback/src/main/java/com/google/cloud/logging/logback/LoggingAppender.java
@@ -38,6 +38,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import javax.annotation.Nonnull;
 
 /**
  * <a href="https://logback.qos.ch/">Logback</a> appender for StackDriver Cloud Logging.
@@ -60,6 +61,10 @@
  *   <li>&lt;enhancer&gt;com.example.enhancer2&lt;/enhancer&gt;
  *   <li>&lt;/appender&gt;
  * </ul>
+ *
+ * Users can extend this class and override the method {@link #createLoggingOptions()} if you need
+ * to specify custom {@link LoggingOptions}, and reference the subclass in logback.xml instead of
+ * {@link LoggingAppender}.
  */
 public class LoggingAppender extends UnsynchronizedAppenderBase<ILoggingEvent> {
 
@@ -186,7 +191,7 @@ public synchronized void start() {
   }
 
   String getProjectId() {
-    return LoggingOptions.getDefaultInstance().getProjectId();
+    return createLoggingOptions().getProjectId();
   }
 
   @Override
@@ -212,13 +217,29 @@ Logging getLogging() {
     if (logging == null) {
       synchronized (this) {
         if (logging == null) {
-          logging = LoggingOptions.getDefaultInstance().getService();
+          logging = createLoggingOptions().getService();
         }
       }
     }
     return logging;
   }
 
+  /**
+   * Creates the {@link LoggingOptions} to use for this {@link LoggingAppender}. Users can subclass
+   * {@link LoggingAppender} and override this method if they need to supply custom {@link
+   * LoggingOptions}, such as a specific credentials file. The default implementation returns {@link
+   * LoggingOptions#getDefaultInstance()}. Make sure to reference your own subclass in your logback
+   * configuration instead of {@link LoggingAppender} if you want to use custom {@link
+   * LoggingOptions}.
+   *
+   * @return the {@link LoggingOptions} that should be used for this {@link LoggingAppender}. May
+   *     not be <code>null</code>.
+   */
+  @Nonnull
+  public LoggingOptions createLoggingOptions() {
+    return LoggingOptions.getDefaultInstance();
+  }
+
   private LogEntry logEntryFor(ILoggingEvent e) {
     StringBuilder payload = new StringBuilder(e.getFormattedMessage()).append('\n');
     writeStack(e.getThrowableProxy(), "", payload);