Added support for logging in JSON format to a file.

Signed-off-by: Nick Wemekamp <N.Wemekamp@justid.nl>

Author: Nick Wemekamp

README.md

@@ -125,9 +125,15 @@ This section outlines the steps that are required to add the Weblogic Logging Ex
    you can find this JAR file in your local maven repository at `~/.m2/repository/org/yaml/snakeyaml/1.27/snakeyaml-1.27.jar`.
    Otherwise, you can download it from [Maven Central](https://search.maven.org/artifact/org.yaml/snakeyaml/1.27/bundle).
 
-   Place this file in a suitable location, e.g. your domain directory.
+   If you want to write the JSON logs to a file instead of sending it elasticsearch directly you will also need these jars:
+   - ecs-logging-core-1.1.0.jar (used for JSON logging, https://mvnrepository.com/artifact/co.elastic.logging/ecs-logging-core)
+   - jul-ecs-formatter-1.1.0.jar (used for JSON logging, https://mvnrepository.com/artifact/co.elastic.logging/jul-ecs-formatter/1.1.0)
+   - slf4j-api-1.7.32.jar (optional and is used for MDC, https://mvnrepository.com/artifact/org.slf4j/slf4j-api)
+   - slf4j-jdk14-1.7.32.jar (optional and is used for MDC, https://mvnrepository.com/artifact/org.slf4j/slf4j-jdk14)
 
-   Update the server classpath to include these two files.  This can be done by adding a statement to the end of your
+   Place the file(s) in a suitable location, e.g. your domain directory.
+
+   Update the server classpath to include these file(s).  This can be done by adding a statement to the end of your
    `setDomainEnv.sh` script in your domain's `bin` directory as follows (this example assumes your domain
    directory is `/u01/base_domain`):
 
@@ -163,7 +169,10 @@ This section outlines the steps that are required to add the Weblogic Logging Ex
    If you prefer to place the configuration file in a different location, you can set the environment variable
    `WEBLOGIC_LOGGING_EXPORTER_CONFIG_FILE` to point to the location of the file.
 
-1. Restart the servers to activate the changes.  After restarting the servers, they will load the WebLogic
+   If you want to write the JSON logs to a file instead of sending it elasticsearch directly use the following configuration
+   [file](samples/WeblogicFileLoggingExporter.yaml) and adjust it to your needs. Make sure to rename it to WebLogicLoggingExporter.yaml.
+
+6. Restart the servers to activate the changes.  After restarting the servers, they will load the WebLogic
    Logging Exporter and start sending their logs to the specified Elasticsearch instance.  You can then
    access them in Kibana as shown in the example below. You will need to create an index first and then go to
    the visualization page.

pom.xml

@@ -63,6 +63,7 @@
             </plugin>
             <!-- for junit 5 -->
             <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>2.22.2</version>
                 <configuration>
@@ -85,6 +86,7 @@
                 </configuration>
             </plugin>
             <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-failsafe-plugin</artifactId>
                 <version>2.22.1</version>
             </plugin>
@@ -190,6 +192,11 @@
             <artifactId>snakeyaml</artifactId>
             <version>1.27</version>
         </dependency>
+        <dependency>
+            <groupId>co.elastic.logging</groupId>
+            <artifactId>jul-ecs-formatter</artifactId>
+            <version>1.1.0</version>
+        </dependency>
         <dependency>
             <groupId>org.antlr</groupId>
             <artifactId>antlr-complete</artifactId>

samples/WeblogicFileLoggingExporter.yaml

@@ -0,0 +1,15 @@
+# turn off the elasticsearch output
+weblogicLoggingExporterEnabled: false
+
+# configure json logging output
+writeToFileEnabled: true
+# %g is necessary for rollback of log files.
+outputFile: '/var/log/oracle/json-logging%g.log'
+# Max open files
+maxRollbackFiles: 3
+# Max file size in bytes, this is 50 MB
+maxFileSize: 52428800
+# Should the log file be appended to when the new logger is created
+appendToFile: true
+# Optional configuration for specifying which levels get logged to the json log file.
+# fileLoggingLogLevel: INFO

src/main/java/weblogic/logging/exporter/Startup.java

@@ -4,8 +4,13 @@
 package weblogic.logging.exporter;
 
 import java.io.File;
+import java.util.logging.FileHandler;
+import java.util.logging.Level;
 import java.util.logging.Logger;
+
+import co.elastic.logging.jul.EcsFormatter;
 import weblogic.logging.LoggingHelper;
+import weblogic.logging.ServerLoggingHandler;
 import weblogic.logging.exporter.config.Config;
 
 public class Startup {
@@ -15,7 +20,6 @@ public class Startup {
   public static void main(String[] argv) {
     System.out.println("======================= Weblogic Logging Exporter Startup class called");
     try {
-      // Logger logger = LoggingHelper.getDomainLogger();
       Logger logger = LoggingHelper.getServerLogger();
 
       /*
@@ -41,12 +45,26 @@ public static void main(String[] argv) {
       System.out.println("Reading configuration from file name: " + file.getAbsolutePath());
       Config config = Config.loadConfig(file);
       System.out.println(config);
+
+      //  Elastic log handler is enabled or the file log handler
       if (config.getEnabled()) {
         logger.addHandler(new LogExportHandler(config));
-      } else {
-        System.out.println("WebLogic Logging Exporter is disabled");
+      } else if (config.isFileLoggingEnabled()) {
+        // Because of this bridge log messages in the applications themselves are being forwarded to the server logger.
+        // so that logging in ear/war artifacts are also visible to the server logger and appear in the JSON log file.
+        Logger.getLogger("").addHandler(new ServerLoggingHandler());
+
+        // Register a file handler using the provided config
+        FileHandler fh = new FileHandler(config.getOutputFile(), config.getMaxFileSize(), config.getGetMaxRollbackFiles(), config.getAppendToFile());
+        fh.setLevel(Level.parse(config.getFileLoggingLogLevel()));
+        fh.setFormatter(new EcsFormatter());
+        logger.addHandler(fh);
+       } else {
+        System.out.println("WebLogic Elasticsearch Logging Exporter is disabled");
       }
-    } catch (Exception e) {
+      // also catch errors so that Weblogic does not crash when a required library was not placed in the classpath correctly.
+    } catch (Error | Exception e) {
+      System.out.println("======================= Something went wrong, the Weblogic Logging Exporter is not activated");
       e.printStackTrace();
     }
   }

src/main/java/weblogic/logging/exporter/config/Config.java

@@ -31,6 +31,13 @@ public class Config {
   private static final String INDEX_NAME = "weblogicLoggingIndexName";
   private static final String DOMAIN_UID = "domainUID";
 
+  private static final String WRITE_TO_FILE_ENABLED = "writeToFileEnabled";
+  private static final String OUTPUT_FILE = "outputFile";
+  private static final String MAX_ROLLBACK_FILES = "maxRollbackFiles";
+  private static final String MAX_FILE_SIZE = "maxFileSize";
+  private static final String APPEND_TO_FILE = "appendToFile";
+  private static final String FILE_LOGGING_LOG_LEVEL = "fileLoggingLogLevel";
+
   private String host = DEFAULT_HOST;
   private int port = DEFAULT_PORT;
   private String indexName = DEFAULT_INDEX_NAME;
@@ -40,6 +47,14 @@ public class Config {
   private final List<FilterConfig> filterConfigs = new ArrayList<>();
   private String domainUID = DEFAULT_DOMAIN_UID;
 
+  private boolean fileLoggingEnabled;
+  private String outputFile;
+  private Integer getMaxRollbackFiles;
+  private Integer maxFileSize;
+  private boolean appendToFile;
+
+  private String fileLoggingLogLevel = "INFO";
+
   private Config() {}
 
   private Config(Map<String, Object> yaml) {
@@ -76,6 +91,26 @@ private Config(Map<String, Object> yaml) {
       System.out.println("Index name is converted to all lower case : " + indexName);
     }
     if (yaml.containsKey(FILTERS)) appendFilters(yaml.get(FILTERS));
+
+    // File output
+    if (yaml.containsKey(WRITE_TO_FILE_ENABLED)) {
+      fileLoggingEnabled = MapUtils.getBooleanValue(yaml, WRITE_TO_FILE_ENABLED);
+    }
+    if (yaml.containsKey(OUTPUT_FILE)) {
+      outputFile = MapUtils.getStringValue(yaml, OUTPUT_FILE);
+    }
+    if (yaml.containsKey(MAX_ROLLBACK_FILES)) {
+      getMaxRollbackFiles = MapUtils.getIntegerValue(yaml, MAX_ROLLBACK_FILES);
+    }
+    if (yaml.containsKey(MAX_FILE_SIZE)) {
+      maxFileSize = MapUtils.getIntegerValue(yaml, MAX_FILE_SIZE);
+    }
+    if (yaml.containsKey(APPEND_TO_FILE)) {
+      appendToFile = MapUtils.getBooleanValue(yaml, APPEND_TO_FILE);
+    }
+    if (yaml.containsKey(FILE_LOGGING_LOG_LEVEL)) {
+      fileLoggingLogLevel = MapUtils.getStringValue(yaml, FILE_LOGGING_LOG_LEVEL);
+    }
   }
 
   public static Config loadConfig(File file) {
@@ -143,29 +178,22 @@ private static Config loadConfig(Map<String, Object> yamlConfig) {
 
   @Override
   public String toString() {
-    return "Config{"
-        + "weblogicLoggingIndexName='"
-        + indexName
-        + '\''
-        + ", publishHost='"
-        + host
-        + '\''
-        + ", publishPort="
-        + port
-        + ", weblogicLoggingExporterSeverity='"
-        + severity
-        + '\''
-        + ", weblogicLoggingExporterBulkSize='"
-        + bulkSize
-        + '\''
-        + ", enabled="
-        + enabled
-        + ", weblogicLoggingExporterFilters="
-        + filterConfigs
-        + ", domainUID='"
-        + domainUID
-        + '\''
-        + '}';
+    return "Config{" +
+            "host='" + host + '\'' +
+            ", port=" + port +
+            ", indexName='" + indexName + '\'' +
+            ", bulkSize=" + bulkSize +
+            ", enabled=" + enabled +
+            ", severity='" + severity + '\'' +
+            ", filterConfigs=" + filterConfigs +
+            ", domainUID='" + domainUID + '\'' +
+            ", fileLoggingEnabled=" + fileLoggingEnabled +
+            ", outputFile='" + outputFile + '\'' +
+            ", getMaxRollbackFiles=" + getMaxRollbackFiles +
+            ", maxFileSize=" + maxFileSize +
+            ", appendToFile=" + appendToFile +
+            ", fileLoggingLogLevel='" + fileLoggingLogLevel + '\'' +
+            '}';
   }
 
   public String getHost() {
@@ -199,4 +227,28 @@ public int getBulkSize() {
   public String getDomainUID() {
     return domainUID;
   }
+
+  public boolean isFileLoggingEnabled() {
+    return fileLoggingEnabled;
+  }
+
+  public String getOutputFile() {
+    return outputFile;
+  }
+
+  public Integer getGetMaxRollbackFiles() {
+    return getMaxRollbackFiles;
+  }
+
+  public Integer getMaxFileSize() {
+    return maxFileSize;
+  }
+
+  public boolean getAppendToFile() {
+    return appendToFile;
+  }
+
+  public String getFileLoggingLogLevel() {
+    return fileLoggingLogLevel;
+  }
 }

src/test/java/weblogic/logging/exporter/config/ConfigTest.java

@@ -22,12 +22,7 @@ public class ConfigTest {
   private final PrintStream originalOut = System.out;
   private final PrintStream originalErr = System.err;
 
-  private static final String EXPECTED_STRING =
-      "Config{weblogicLoggingIndexName='index1', publishHost='host1', "
-          + "publishPort=1234, weblogicLoggingExporterSeverity='Warning', "
-          + "weblogicLoggingExporterBulkSize='2', enabled=false, "
-          + "weblogicLoggingExporterFilters=[FilterConfig{expression='MSGID != 'BEA-000449'', "
-          + "servers=[]}], domainUID='domain1'}";
+  private static final String EXPECTED_STRING = "Config{host='host1', port=1234, indexName='index1', bulkSize=2, enabled=false, severity='Warning', filterConfigs=[FilterConfig{expression='MSGID != 'BEA-000449'', servers=[]}], domainUID='domain1', fileLoggingEnabled=false, outputFile='null', getMaxRollbackFiles=null, maxFileSize=null, appendToFile=false, fileLoggingLogLevel='INFO'}";
 
   @BeforeEach
   public void setUpStreams() {
@@ -115,6 +110,7 @@ public void shouldConvertIndexNameToLowerCase() {
   @Test
   public void checkToStringWorksAsExpected() {
     Config config = Config.loadConfig(new File("src/test/resources/config1.yaml"));
+    System.out.println(config.toString());
     assertEquals(EXPECTED_STRING, config.toString());
   }
 }