setting to exclude MDC keys from being sent to Elastic

README.md

@@ -37,6 +37,7 @@ In your `logback.xml`:
             <sleepTime>250</sleepTime> <!-- optional (in ms, default 250) -->
             <rawJsonMessage>false</rawJsonMessage> <!-- optional (default false) -->
             <includeMdc>false</includeMdc> <!-- optional (default false) -->
+            <excludedMdcKeys>stacktrace</excludedMdcKeys> <!-- optional (default empty) -->
             <maxMessageSize>100</maxMessageSize> <!-- optional (default -1 -->
             <authentication class="com.internetitem.logback.elasticsearch.config.BasicAuthentication" /> <!-- optional -->
             <properties>
@@ -108,6 +109,7 @@ Configuration Reference
  * `errorLoggerName` (optional): If set, any internal errors or problems will be logged to this logger
  * `rawJsonMessage` (optional, default false): If set to `true`, the log message is interpreted as pre-formatted raw JSON message.
  * `includeMdc` (optional, default false): If set to `true`, then all [MDC](http://www.slf4j.org/api/org/slf4j/MDC.html) values will be mapped to properties on the JSON payload.
+ * `excludedMdcKeys` (optional, default empty): comma separated (extra whitespace is fine) list of case sensitive MDC keys that should not be mapped automatically to properties; only useful when includeMdc is set to `true`
  * `maxMessageSize` (optional, default -1): If set to a number greater than 0, truncate messages larger than this length, then append "`..`" to denote that the message was truncated
  * `authentication` (optional): Add the ability to send authentication headers (see below)
 

src/main/java/com/internetitem/logback/elasticsearch/AbstractElasticsearchAppender.java

@@ -1,16 +1,13 @@
 package com.internetitem.logback.elasticsearch;
 
+import ch.qos.logback.core.UnsynchronizedAppenderBase;
+import com.internetitem.logback.elasticsearch.config.*;
+import com.internetitem.logback.elasticsearch.util.ErrorReporter;
+
 import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
 
-import ch.qos.logback.core.UnsynchronizedAppenderBase;
-import com.internetitem.logback.elasticsearch.config.Authentication;
-import com.internetitem.logback.elasticsearch.config.ElasticsearchProperties;
-import com.internetitem.logback.elasticsearch.config.HttpRequestHeaders;
-import com.internetitem.logback.elasticsearch.config.Settings;
-import com.internetitem.logback.elasticsearch.util.ErrorReporter;
-
 public abstract class AbstractElasticsearchAppender<T> extends UnsynchronizedAppenderBase<T> {
 
 	protected Settings settings;
@@ -131,6 +128,10 @@ public void setIncludeMdc(boolean includeMdc) {
 		settings.setIncludeMdc(includeMdc);
 	}
 
+	public void setExcludedMdcKeys(String setExcludedMdcKeys) {
+		settings.setExcludedMdcKeys(setExcludedMdcKeys);
+	}
+
     public void setAuthentication(Authentication auth) {
         settings.setAuthentication(auth);
     }

src/main/java/com/internetitem/logback/elasticsearch/ClassicElasticsearchPublisher.java

@@ -1,8 +1,5 @@
 package com.internetitem.logback.elasticsearch;
 
-import java.io.IOException;
-import java.util.Map;
-
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.Context;
 import com.fasterxml.jackson.core.JsonGenerator;
@@ -14,10 +11,35 @@
 import com.internetitem.logback.elasticsearch.util.ClassicPropertyAndEncoder;
 import com.internetitem.logback.elasticsearch.util.ErrorReporter;
 
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+
 public class ClassicElasticsearchPublisher extends AbstractElasticsearchPublisher<ILoggingEvent> {
+    private final List<String> excludedMdcKeys;
 
     public ClassicElasticsearchPublisher(Context context, ErrorReporter errorReporter, Settings settings, ElasticsearchProperties properties, HttpRequestHeaders headers) throws IOException {
         super(context, errorReporter, settings, properties, headers);
+
+        excludedMdcKeys = getExcludedMdcKeys();
+    }
+
+    private List<String> getExcludedMdcKeys() {
+        /*
+         * using a List instead of a Map because the assumption is that
+         * the number of excluded keys will be very small and not cause
+         * a performance issue
+         */
+        List<String> result = new ArrayList<>();
+        if (settings.getExcludedMdcKeys() != null) {
+            String[] parts = settings.getExcludedMdcKeys().split(",");
+            for (String part : parts) {
+                result.add(part.trim());
+            }
+        }
+        return result;
     }
 
     @Override
@@ -40,9 +62,11 @@ protected void serializeCommonFields(JsonGenerator gen, ILoggingEvent event) thr
             gen.writeObjectField("message", formattedMessage);
         }
 
-        if(settings.isIncludeMdc()) {
+        if (settings.isIncludeMdc()) {
             for (Map.Entry<String, String> entry : event.getMDCPropertyMap().entrySet()) {
-                gen.writeObjectField(entry.getKey(), entry.getValue());
+                if (!excludedMdcKeys.contains(entry.getKey())) {
+                    gen.writeObjectField(entry.getKey(), entry.getValue());
+                }
             }
         }
     }

src/main/java/com/internetitem/logback/elasticsearch/config/Settings.java

@@ -19,6 +19,7 @@ public class Settings {
 	private boolean errorsToStderr;
 	private boolean includeCallerData;
 	private boolean includeMdc;
+	private String excludedMdcKeys;
 	private boolean rawJsonMessage;
 	private int maxQueueSize = 100 * 1024 * 1024;
 	private Authentication authentication;
@@ -155,6 +156,14 @@ public void setIncludeMdc(boolean includeMdc) {
 		this.includeMdc = includeMdc;
 	}
 
+	public String getExcludedMdcKeys() {
+		return excludedMdcKeys;
+	}
+
+	public void setExcludedMdcKeys(String excludedMdcKeys) {
+		this.excludedMdcKeys = excludedMdcKeys;
+	}
+
 	public int getMaxMessageSize() {
 		return maxMessageSize;
 	}

src/test/java/com/internetitem/logback/elasticsearch/ElasticsearchAppenderTest.java

@@ -176,6 +176,7 @@ public void should_delegate_setters_to_settings() throws MalformedURLException {
         boolean errorsToStderr = false;
         boolean rawJsonMessage = false;
         boolean includeMdc = true;
+        String excludedMdcKeys = "stacktrace,url";
         String index = "app-logs";
         String type = "appenderType";
         int maxQueueSize = 10;
@@ -202,6 +203,7 @@ public void should_delegate_setters_to_settings() throws MalformedURLException {
         appender.setConnectTimeout(connectTimeout);
         appender.setRawJsonMessage(rawJsonMessage);
         appender.setIncludeMdc(includeMdc);
+        appender.setExcludedMdcKeys(excludedMdcKeys);
 
         verify(settings, times(1)).setReadTimeout(readTimeout);
         verify(settings, times(1)).setSleepTime(aSleepTime);
@@ -218,6 +220,7 @@ public void should_delegate_setters_to_settings() throws MalformedURLException {
         verify(settings, times(1)).setConnectTimeout(connectTimeout);
         verify(settings, times(1)).setRawJsonMessage(rawJsonMessage);
         verify(settings, times(1)).setIncludeMdc(includeMdc);
+        verify(settings, times(1)).setExcludedMdcKeys(excludedMdcKeys);
     }