Add Filter to Get VCAP metadate from Environment

Author: KarstenSchnitter

cf-java-logging-support-servlet/src/main/java/com/sap/hcp/cf/logging/servlet/filter/AddVcapEnvironmentToLogContextFilter.java

@@ -0,0 +1,34 @@
+package com.sap.hcp.cf.logging.servlet.filter;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import com.sap.hcp.cf.logging.common.LogContext;
+
+/**
+ * <p>
+ * The {@link AddVcapEnvironmentToLogContextFilter} extracts CF specific
+ * metadata about the running application and adds it to the log context. The
+ * metadata includes the app, org and space names and ids. This allows to
+ * attribute a generated log message to the correct source from the message
+ * alone.
+ * </p>
+ * 
+ * <p>
+ * <b>Note:</b> This metadata can usually also be obtained from the CF channel
+ * shipping the logs, e.g. syslog structured data. Hence, depending on the
+ * use-case, it may not be required to add the metadata with this filter.
+ * </p>
+ */
+public class AddVcapEnvironmentToLogContextFilter extends AbstractLoggingFilter {
+
+    @Override
+    protected void preProcess(HttpServletRequest request, HttpServletResponse response) {
+        LogContext.loadContextFields();
+    }
+
+    @Override
+    protected void postProcess(HttpServletRequest request, HttpServletResponse response) {
+        LogContext.resetContextFields();
+    }
+}