fix(cloud-logging): removing Logstash dependencies, using Cloud Logging Logback (#10274)

* refactor: migrate Logstash logging to MDC and Google Cloud Logging appender while updating dependencies and test configuration

* build: removed Jacoco library override and skip for local testing, not neccesary for cloud test

* fix: restore original System.out in AppTest teardown to prevent side effects on other tests

* docs: add output_structured_log.md example for Cloud Run manual logging

Author: Kef131

run/logging-manual/output_structured_log.md

@@ -0,0 +1,3 @@
+<!-- [START cloudrun_manual_logging_output] -->
+{"severity":"INFO","time":"YYYY-MM-DDTHH:MM:SS.SSSZ","logging.googleapis.com/labels":{"component":"arbitrary-property","levelName":"INFO","loggerName":"com.example.cloudrun.App","levelValue":"20000"},"logging.googleapis.com/trace_sampled":false,"message":"This is the default display field."}
+<!-- [END cloudrun_manual_logging_output] -->

run/logging-manual/pom.xml

@@ -28,6 +28,18 @@ limitations under the License.
     <maven.compiler.target>17</maven.compiler.target>
   </properties>
 
+  <dependencyManagement>
+    <dependencies>
+      <dependency>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>libraries-bom</artifactId>
+        <version>26.32.0</version>
+        <type>pom</type>
+        <scope>import</scope>
+      </dependency>
+    </dependencies>
+  </dependencyManagement>
+
   <dependencies>
     <dependency>
       <groupId>com.sparkjava</groupId>
@@ -40,9 +52,13 @@ limitations under the License.
       <version>2.0.12</version>
     </dependency>
     <dependency>
-      <groupId>net.logstash.logback</groupId>
-      <artifactId>logstash-logback-encoder</artifactId>
-      <version>7.4</version>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>google-cloud-logging-logback</artifactId>
+    </dependency>
+    <dependency>
+      <groupId>ch.qos.logback</groupId>
+      <artifactId>logback-core</artifactId>
+      <version>1.4.14</version>
     </dependency>
     <dependency>
       <groupId>ch.qos.logback</groupId>

run/logging-manual/src/main/java/com/example/cloudrun/App.java

@@ -16,7 +16,6 @@
 
 package com.example.cloudrun;
 
-import static net.logstash.logback.argument.StructuredArguments.kv;
 import static spark.Spark.get;
 import static spark.Spark.port;
 
@@ -27,6 +26,7 @@
 import okhttp3.Response;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.slf4j.MDC;
 
 public class App {
 
@@ -41,30 +41,27 @@ public static void main(String[] args) {
         "/",
         (req, res) -> {
           // [START cloudrun_manual_logging]
-          // Build structured log messages as an object.
-          Object globalLogFields = null;
-
           // Add log correlation to nest all log messages beneath request log in Log Viewer.
           // TODO(developer): delete this code if you're creating a Cloud
           //                  Function and it is *NOT* triggered by HTTP.
           String traceHeader = req.headers("x-cloud-trace-context");
           if (traceHeader != null && project != null) {
             String trace = traceHeader.split("/")[0];
-            globalLogFields =
-                kv(
-                    "logging.googleapis.com/trace",
-                    String.format("projects/%s/traces/%s", project, trace));
+            MDC.put(
+                "logging.googleapis.com/trace",
+                String.format("projects/%s/traces/%s", project, trace));
           }
           // -- End log correlation code --
 
-          // Create a structured log entry using key value pairs.
+          // Create a structured log entry using MDC (Mapped Diagnostic Context) keys.
           // For instantiating the "logger" variable, see
           // https://cloud.google.com/run/docs/logging#run_manual_logging-java
-          logger.error(
-              "This is the default display field.",
-              kv("component", "arbitrary-property"),
-              kv("severity", "NOTICE"),
-              globalLogFields);
+          MDC.put("component", "arbitrary-property");
+
+          logger.info("This is the default display field.");
+
+          // Clear MDC at the end of the request to avoid resource leaks
+          MDC.clear();
           // [END cloudrun_manual_logging]
           res.status(200);
           return "Hello Logger!";

run/logging-manual/src/main/resources/logback.xml

@@ -1,21 +1,20 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <!-- [START cloudrun_manual_logging_logback] -->
 <configuration>
-  <appender name="jsonConsoleAppender" class="ch.qos.logback.core.ConsoleAppender">
-    <encoder class="net.logstash.logback.encoder.LogstashEncoder">
-      <!-- Ignore default logging fields -->
-      <fieldNames>
-        <timestamp>[ignore]</timestamp>
-        <version>[ignore]</version>
-        <logger>[ignore]</logger>
-        <thread>[ignore]</thread>
-        <level>[ignore]</level>
-        <levelValue>[ignore]</levelValue>
-      </fieldNames>
-    </encoder>
+  <appender name="CLOUD" class="com.google.cloud.logging.logback.LoggingAppender">
+    <!-- Optional : filter logs at or above a level -->
+    <filter class="ch.qos.logback.classic.filter.ThresholdFilter">
+      <level>INFO</level>
+    </filter>
+    <log>application.log</log> <!-- Optional : default java.log -->
+    <resourceType>gae_app</resourceType> <!-- Optional : default: auto-detected, fallback: global -->
+    <enhancer>com.example.logging.logback.enhancers.ExampleEnhancer</enhancer> <!-- Optional -->
+    <flushLevel>WARN</flushLevel> <!-- Optional : default ERROR -->
+    <!-- Redirect logs to stdout in JSON format for Cloud Run to capture -->
+    <redirectToStdout>true</redirectToStdout>
   </appender>
   <root level="INFO">
-    <appender-ref ref="jsonConsoleAppender"/>
+    <appender-ref ref="CLOUD"/>
   </root>
 </configuration>
-<!-- [END cloudrun_manual_logging_logback] -->
+<!-- [END cloudrun_manual_logging_logback] -->

run/logging-manual/src/test/java/com/example/cloudrun/AppTest.java

@@ -34,26 +34,31 @@
 
 public class AppTest {
 
-  private ByteArrayOutputStream bout;
-  private PrintStream out;
+  private static ByteArrayOutputStream bout;
+  private static PrintStream out;
+  private static PrintStream originalOut;
 
   @BeforeClass
   public static void beforeClass() {
+    originalOut = System.out;
+    bout = new ByteArrayOutputStream();
+    out = new PrintStream(bout);
+    System.setOut(out);
+
     App app = new App();
     app.main(new String[] {});
     awaitInitialization();
   }
 
   @AfterClass
   public static void afterClass() {
+    System.setOut(originalOut);
     stop();
   }
 
   @Before
   public void setUp() {
-    bout = new ByteArrayOutputStream();
-    out = new PrintStream(bout);
-    System.setOut(out);
+    bout.reset();
   }
 
   @Test
@@ -63,7 +68,7 @@ public void shouldSucceed() throws IOException {
     assertEquals("Hello Logger!", response.body);
     String output = bout.toString();
     assertTrue(output.toString().contains("This is the default display field."));
-    assertTrue(output.toString().contains("NOTICE"));
+    assertTrue(output.toString().contains("INFO"));
     assertTrue(output.toString().contains("arbitrary-property"));
   }