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 019package org.apache.hadoop.lib.servlet; 020 021import org.apache.hadoop.classification.InterfaceAudience; 022import org.slf4j.MDC; 023 024import javax.servlet.Filter; 025import javax.servlet.FilterChain; 026import javax.servlet.FilterConfig; 027import javax.servlet.ServletException; 028import javax.servlet.ServletRequest; 029import javax.servlet.ServletResponse; 030import javax.servlet.http.HttpServletRequest; 031import java.io.IOException; 032import java.security.Principal; 033 034/** 035 * Filter that sets request contextual information for the slf4j MDC. 036 * <p/> 037 * It sets the following values: 038 * <ul> 039 * <li>hostname: if the {@link HostnameFilter} is present and configured 040 * before this filter</li> 041 * <li>user: the <code>HttpServletRequest.getUserPrincipal().getName()</code></li> 042 * <li>method: the HTTP method fo the request (GET, POST, ...)</li> 043 * <li>path: the path of the request URL</li> 044 * </ul> 045 */ 046@InterfaceAudience.Private 047public class MDCFilter implements Filter { 048 049 /** 050 * Initializes the filter. 051 * <p/> 052 * This implementation is a NOP. 053 * 054 * @param config filter configuration. 055 * 056 * @throws ServletException thrown if the filter could not be initialized. 057 */ 058 @Override 059 public void init(FilterConfig config) throws ServletException { 060 } 061 062 /** 063 * Sets the slf4j <code>MDC</code> and delegates the request to the chain. 064 * 065 * @param request servlet request. 066 * @param response servlet response. 067 * @param chain filter chain. 068 * 069 * @throws IOException thrown if an IO error occurrs. 070 * @throws ServletException thrown if a servet error occurrs. 071 */ 072 @Override 073 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 074 throws IOException, ServletException { 075 try { 076 MDC.clear(); 077 String hostname = HostnameFilter.get(); 078 if (hostname != null) { 079 MDC.put("hostname", HostnameFilter.get()); 080 } 081 Principal principal = ((HttpServletRequest) request).getUserPrincipal(); 082 String user = (principal != null) ? principal.getName() : null; 083 if (user != null) { 084 MDC.put("user", user); 085 } 086 MDC.put("method", ((HttpServletRequest) request).getMethod()); 087 MDC.put("path", ((HttpServletRequest) request).getPathInfo()); 088 chain.doFilter(request, response); 089 } finally { 090 MDC.clear(); 091 } 092 } 093 094 /** 095 * Destroys the filter. 096 * <p/> 097 * This implementation is a NOP. 098 */ 099 @Override 100 public void destroy() { 101 } 102} 103