001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, software 013 * distributed under the License is distributed on an "AS IS" BASIS, 014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 015 * See the License for the specific language governing permissions and 016 * limitations under the License. 017 */ 018 019 package org.apache.hadoop.lib.servlet; 020 021 import org.slf4j.MDC; 022 023 import javax.servlet.Filter; 024 import javax.servlet.FilterChain; 025 import javax.servlet.FilterConfig; 026 import javax.servlet.ServletException; 027 import javax.servlet.ServletRequest; 028 import javax.servlet.ServletResponse; 029 import javax.servlet.http.HttpServletRequest; 030 import java.io.IOException; 031 import java.security.Principal; 032 033 /** 034 * Filter that sets request contextual information for the slf4j MDC. 035 * <p/> 036 * It sets the following values: 037 * <ul> 038 * <li>hostname: if the {@link HostnameFilter} is present and configured 039 * before this filter</li> 040 * <li>user: the <code>HttpServletRequest.getUserPrincipal().getName()</code></li> 041 * <li>method: the HTTP method fo the request (GET, POST, ...)</li> 042 * <li>path: the path of the request URL</li> 043 * </ul> 044 */ 045 public class MDCFilter implements Filter { 046 047 /** 048 * Initializes the filter. 049 * <p/> 050 * This implementation is a NOP. 051 * 052 * @param config filter configuration. 053 * 054 * @throws ServletException thrown if the filter could not be initialized. 055 */ 056 @Override 057 public void init(FilterConfig config) throws ServletException { 058 } 059 060 /** 061 * Sets the slf4j <code>MDC</code> and delegates the request to the chain. 062 * 063 * @param request servlet request. 064 * @param response servlet response. 065 * @param chain filter chain. 066 * 067 * @throws IOException thrown if an IO error occurrs. 068 * @throws ServletException thrown if a servet error occurrs. 069 */ 070 @Override 071 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 072 throws IOException, ServletException { 073 try { 074 MDC.clear(); 075 String hostname = HostnameFilter.get(); 076 if (hostname != null) { 077 MDC.put("hostname", HostnameFilter.get()); 078 } 079 Principal principal = ((HttpServletRequest) request).getUserPrincipal(); 080 String user = (principal != null) ? principal.getName() : null; 081 if (user != null) { 082 MDC.put("user", user); 083 } 084 MDC.put("method", ((HttpServletRequest) request).getMethod()); 085 MDC.put("path", ((HttpServletRequest) request).getPathInfo()); 086 chain.doFilter(request, response); 087 } finally { 088 MDC.clear(); 089 } 090 } 091 092 /** 093 * Destroys the filter. 094 * <p/> 095 * This implementation is a NOP. 096 */ 097 @Override 098 public void destroy() { 099 } 100 } 101