BAEL-1230: Get Java Logs into the JSON Format (#3381)

* Added code for BAEL-1230: Getting log in JSON format

* Added code for BAEL-1230: Getting log in JSON format

* Improved tests to check correct JSON format in logs

* Renamed Test classes to make clear what they do

* Fixed wrong indentation

logging-modules/logback/pom.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
                              http://maven.apache.org/xsd/maven-4.0.0.xsd">
 
     <modelVersion>4.0.0</modelVersion>
@@ -12,6 +12,8 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <logback.version>1.2.3</logback.version>
+        <logback.contrib.version>0.1.5</logback.contrib.version>
+        <jackson.version>2.9.3</jackson.version>
     </properties>
 
     <parent>
@@ -28,7 +30,21 @@
             <artifactId>logback-classic</artifactId>
             <version>${logback.version}</version>
         </dependency>
-
+        <dependency>
+            <groupId>ch.qos.logback.contrib</groupId>
+            <artifactId>logback-json-classic</artifactId>
+            <version>${logback.contrib.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>ch.qos.logback.contrib</groupId>
+            <artifactId>logback-jackson</artifactId>
+            <version>${logback.contrib.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>com.fasterxml.jackson.core</groupId>
+            <artifactId>jackson-databind</artifactId>
+            <version>${jackson.version}</version>
+        </dependency>
     </dependencies>
 
 

logging-modules/logback/src/test/java/com/baeldung/logback/JSONLayoutTest.java

@@ -0,0 +1,45 @@
+package com.baeldung.logback;
+
+import static org.junit.Assert.assertTrue;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.PrintStream;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class JSONLayoutTest {
+
+    private static Logger logger;
+    private ByteArrayOutputStream consoleOutput = new ByteArrayOutputStream();
+    private PrintStream ps = new PrintStream(consoleOutput);
+
+    @Before
+    public void setUp() {
+        // Redirect console output to our stream
+        System.setOut(ps);
+        logger = LoggerFactory.getLogger("jsonLogger");
+    }
+
+    @Test
+    public void whenLogLayoutInJSON_thenOutputIsCorrectJSON() {
+        logger.debug("Debug message");
+        String currentLog = consoleOutput.toString();
+        assertTrue(!currentLog.isEmpty() && isValidJSON(currentLog));
+    }
+
+    public static boolean isValidJSON(String jsonInString) {
+        try {
+            final ObjectMapper mapper = new ObjectMapper();
+            mapper.readTree(jsonInString);
+            return true;
+        } catch (IOException e) {
+            return false;
+        }
+    }
+}

logging-modules/logback/src/test/resources/logback-test.xml

@@ -1,14 +1,31 @@
-<configuration debug="true">
+<configuration debug="false">
+
+    <statusListener class="ch.qos.logback.core.status.NopStatusListener" />
 
     <appender name="map" class="com.baeldung.logback.MapAppender">
         <prefix>test</prefix>
     </appender>
 
-    <appender name="badMap" class="com.baeldung.logback.MapAppender"/>
+    <appender name="badMap" class="com.baeldung.logback.MapAppender" />
+
+    # JSON appender
+    <appender name="json" class="ch.qos.logback.core.ConsoleAppender">
+        <layout class="ch.qos.logback.contrib.json.classic.JsonLayout">
+            <jsonFormatter
+                class="ch.qos.logback.contrib.jackson.JacksonJsonFormatter">
+                <prettyPrint>true</prettyPrint>
+            </jsonFormatter>
+            <timestampFormat>yyyy-MM-dd' 'HH:mm:ss.SSS</timestampFormat>
+        </layout>
+    </appender>
+
+    <logger name="jsonLogger" level="TRACE">
+        <appender-ref ref="json" />
+    </logger>
 
     <root level="debug">
-        <appender-ref ref="map"/>
-        <appender-ref ref="badMap"/>
+        <appender-ref ref="map" />
+        <appender-ref ref="badMap" />
     </root>
 
 </configuration>