1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache license, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the license for the specific language governing permissions and
15 * limitations under the license.
16 */
17 package org.apache.logging.log4j.core.lookup;
18
19 import org.apache.logging.log4j.core.LogEvent;
20 import org.apache.logging.log4j.core.config.plugins.Plugin;
21
22 /**
23 * Looks up keys from environment variables.
24 */
25 @Plugin(name = "env", category = StrLookup.CATEGORY)
26 public class EnvironmentLookup extends AbstractLookup {
27
28 /**
29 * Looks up the value of the environment variable.
30 * @param event The current LogEvent (is ignored by this StrLookup).
31 * @param key the key to be looked up, may be null
32 * @return The value of the environment variable.
33 */
34 @Override
35 public String lookup(final LogEvent event, final String key) {
36 return System.getenv(key);
37 }
38 }