001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017package org.apache.logging.log4j.core.lookup; 018 019import org.apache.logging.log4j.core.LogEvent; 020import org.apache.logging.log4j.core.config.plugins.Plugin; 021 022/** 023 * Looks up keys from environment variables. 024 */ 025@Plugin(name = "env", category = StrLookup.CATEGORY) 026public class EnvironmentLookup extends AbstractLookup { 027 028 /** 029 * Looks up the value of the environment variable. 030 * @param event The current LogEvent (is ignored by this StrLookup). 031 * @param key the key to be looked up, may be null 032 * @return The value of the environment variable. 033 */ 034 @Override 035 public String lookup(final LogEvent event, final String key) { 036 return System.getenv(key); 037 } 038}