Adjust GcpLayout JSON to latest format (#3586) (#3867)

* Adjust GcpLayout JSON to latest format

First, it formats the log timestamp field to the correct format
recognized by Fluent-Bit (component of Google Cloud Logging) and Google
Ops Agent.

Secondly, severity field now must be prefixed with
logging.googleapis.com.

Third, counter cannot be used for insertId as it is duplicated on
different threads.

And the last but not the least, exception, thread and logger fields are
pretty standard when logging via Logback's JSON layout and Google's
Spring GCP libraries. Field name changes now match these other loggers.

* revert severity changes, remove insertId

* Remove insertid from tests

* fix spotless error

* Switch exception field to use exception resolver

* try to fix timestamp tests

* Fix tests with empty exceptions

* Add changelog

* Improve changelog.

---------

Co-authored-by: Vilius Šumskas <[email protected]>
Co-authored-by: Volkan Yazıcı <[email protected]>

Author: 3 people

log4j-layout-template-json-test/src/test/java/org/apache/logging/log4j/layout/template/json/GcpLayoutTest.java

@@ -20,11 +20,6 @@
 import static org.apache.logging.log4j.layout.template.json.TestHelpers.usingSerializedLogEventAccessor;
 import static org.assertj.core.api.Assertions.assertThat;
 
-import java.time.Instant;
-import java.time.ZoneId;
-import java.time.ZonedDateTime;
-import java.time.format.DateTimeFormatter;
-import java.util.Locale;
 import org.apache.logging.log4j.Level;
 import org.apache.logging.log4j.core.LogEvent;
 import org.apache.logging.log4j.core.impl.ContextDataFactory;
@@ -43,9 +38,6 @@ class GcpLayoutTest {
 
     private static final int LOG_EVENT_COUNT = 1_000;
 
-    private static final DateTimeFormatter DATE_TIME_FORMATTER =
-            DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'", Locale.US);
-
     @Test
     void test_lite_log_events() {
         LogEventFixture.createLiteLogEvents(LOG_EVENT_COUNT).forEach(GcpLayoutTest::verifySerialization);
@@ -83,8 +75,9 @@ private static void verifySerialization(final LogEvent logEvent) {
         usingSerializedLogEventAccessor(LAYOUT, logEvent, accessor -> {
 
             // Verify timestamp.
-            final String expectedTimestamp = formatLogEventInstant(logEvent);
-            assertThat(accessor.getString("timestamp")).isEqualTo(expectedTimestamp);
+            final org.apache.logging.log4j.core.time.Instant instant = logEvent.getInstant();
+            assertThat(accessor.getInteger("timestampSeconds")).isEqualTo(instant.getEpochSecond());
+            assertThat(accessor.getInteger("timestampNanos")).isEqualTo(instant.getNanoOfSecond());
 
             // Verify severity.
             final Level level = logEvent.getLevel();
@@ -147,48 +140,25 @@ private static void verifySerialization(final LogEvent logEvent) {
                         .isEmpty();
             }
 
-            // Verify insert id.
-            assertThat(accessor.getString("logging.googleapis.com/insertId")).matches("[-]?[0-9]+");
-
             // Verify exception.
             if (exception != null) {
 
-                // Verify exception class.
-                assertThat(accessor.getString(new String[] {"_exception", "class"}))
-                        .isEqualTo(exception.getClass().getCanonicalName());
-
-                // Verify exception message.
-                assertThat(accessor.getString(new String[] {"_exception", "message"}))
-                        .isEqualTo(exception.getMessage());
-
                 // Verify exception stack trace.
-                assertThat(accessor.getString(new String[] {"_exception", "stackTrace"}))
+                assertThat(accessor.getString("exception"))
                         .contains(exception.getLocalizedMessage())
                         .contains("at org.apache.logging.log4j.layout.template.json")
                         .contains("at java.base/java.lang.reflect.Method")
                         .contains("at org.junit.platform.engine");
 
             } else {
-                assertThat(accessor.getObject(new String[] {"_exception", "class"}))
-                        .isNull();
-                assertThat(accessor.getObject(new String[] {"_exception", "message"}))
-                        .isNull();
-                assertThat(accessor.getString(new String[] {"_exception", "stackTrace"}))
-                        .isEmpty();
+                assertThat(accessor.getString("exception")).isNull();
             }
 
             // Verify thread name.
-            assertThat(accessor.getString("_thread")).isEqualTo(logEvent.getThreadName());
+            assertThat(accessor.getString("thread")).isEqualTo(logEvent.getThreadName());
 
             // Verify logger name.
-            assertThat(accessor.getString("_logger")).isEqualTo(logEvent.getLoggerName());
+            assertThat(accessor.getString("logger")).isEqualTo(logEvent.getLoggerName());
         });
     }
-
-    private static String formatLogEventInstant(final LogEvent logEvent) {
-        final org.apache.logging.log4j.core.time.Instant instant = logEvent.getInstant();
-        final ZonedDateTime dateTime = Instant.ofEpochSecond(instant.getEpochSecond(), instant.getNanoOfSecond())
-                .atZone(ZoneId.of("UTC"));
-        return DATE_TIME_FORMATTER.format(dateTime);
-    }
 }

log4j-layout-template-json/src/main/resources/GcpLayout.json

@@ -1,10 +1,15 @@
 {
-  "timestamp": {
+  "timestampSeconds": {
     "$resolver": "timestamp",
-    "pattern": {
-      "format": "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'",
-      "timeZone": "UTC",
-      "locale": "en_US"
+    "epoch": {
+      "unit": "secs",
+      "rounded": true
+    }
+  },
+  "timestampNanos": {
+    "$resolver": "timestamp",
+    "epoch": {
+      "unit": "secs.nanos"
     }
   },
   "severity": {
@@ -36,10 +41,6 @@
       "stackTraceEnabled": false
     }
   },
-  "logging.googleapis.com/insertId": {
-    "$resolver": "counter",
-    "stringified": true
-  },
   "logging.googleapis.com/trace": {
     "$resolver": "mdc",
     "key": "trace_id"
@@ -49,25 +50,18 @@
     "key": "span_id"
   },
   "logging.googleapis.com/trace_sampled": true,
-  "_exception": {
-    "class": {
-      "$resolver": "exception",
-      "field": "className"
-    },
-    "message": {
-      "$resolver": "exception",
-      "field": "message"
-    },
+  "exception": {
+    "$resolver": "exception",
+    "field": "stackTrace",
     "stackTrace": {
-      "$resolver": "pattern",
-      "pattern": "%xEx"
+      "stringified": true
     }
   },
-  "_thread": {
+  "thread": {
     "$resolver": "thread",
     "field": "name"
   },
-  "_logger": {
+  "logger": {
     "$resolver": "logger",
     "field": "name"
   }