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 java.util.HashMap;
020import java.util.List;
021import java.util.Locale;
022import java.util.Map;
023
024import org.apache.logging.log4j.Logger;
025import org.apache.logging.log4j.core.LogEvent;
026import org.apache.logging.log4j.core.config.ConfigurationAware;
027import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
028import org.apache.logging.log4j.core.config.plugins.util.PluginType;
029import org.apache.logging.log4j.core.util.Loader;
030import org.apache.logging.log4j.core.util.ReflectionUtil;
031import org.apache.logging.log4j.status.StatusLogger;
032import org.apache.logging.log4j.util.Constants;
033
034/**
035 * Proxies all the other {@link StrLookup}s.
036 */
037public class Interpolator extends AbstractConfigurationAwareLookup {
038
039    private static final String LOOKUP_KEY_WEB = "web";
040
041    private static final String LOOKUP_KEY_DOCKER = "docker";
042
043    private static final String LOOKUP_KEY_JNDI = "jndi";
044
045    private static final String LOOKUP_KEY_JVMRUNARGS = "jvmrunargs";
046
047    private static final Logger LOGGER = StatusLogger.getLogger();
048
049    /** Constant for the prefix separator. */
050    private static final char PREFIX_SEPARATOR = ':';
051
052    private final Map<String, StrLookup> strLookupMap = new HashMap<>();
053
054    private final StrLookup defaultLookup;
055
056    public Interpolator(final StrLookup defaultLookup) {
057        this(defaultLookup, null);
058    }
059
060    /**
061     * Constructs an Interpolator using a given StrLookup and a list of packages to find Lookup plugins in.
062     *
063     * @param defaultLookup  the default StrLookup to use as a fallback
064     * @param pluginPackages a list of packages to scan for Lookup plugins
065     * @since 2.1
066     */
067    public Interpolator(final StrLookup defaultLookup, final List<String> pluginPackages) {
068        this.defaultLookup = defaultLookup == null ? new MapLookup(new HashMap<String, String>()) : defaultLookup;
069        final PluginManager manager = new PluginManager(CATEGORY);
070        manager.collectPlugins(pluginPackages);
071        final Map<String, PluginType<?>> plugins = manager.getPlugins();
072
073        for (final Map.Entry<String, PluginType<?>> entry : plugins.entrySet()) {
074            try {
075                final Class<? extends StrLookup> clazz = entry.getValue().getPluginClass().asSubclass(StrLookup.class);
076                strLookupMap.put(entry.getKey().toLowerCase(), ReflectionUtil.instantiate(clazz));
077            } catch (final Throwable t) {
078                handleError(entry.getKey(), t);
079            }
080        }
081    }
082
083    /**
084     * Create the default Interpolator using only Lookups that work without an event.
085     */
086    public Interpolator() {
087        this((Map<String, String>) null);
088    }
089
090    /**
091     * Creates the Interpolator using only Lookups that work without an event and initial properties.
092     */
093    public Interpolator(final Map<String, String> properties) {
094        this.defaultLookup = new MapLookup(properties == null ? new HashMap<String, String>() : properties);
095        // TODO: this ought to use the PluginManager
096        strLookupMap.put("log4j", new Log4jLookup());
097        strLookupMap.put("sys", new SystemPropertiesLookup());
098        strLookupMap.put("env", new EnvironmentLookup());
099        strLookupMap.put("main", MainMapLookup.MAIN_SINGLETON);
100        strLookupMap.put("marker", new MarkerLookup());
101        strLookupMap.put("java", new JavaLookup());
102        // JNDI
103        try {
104            // [LOG4J2-703] We might be on Android
105            strLookupMap.put(LOOKUP_KEY_JNDI,
106                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JndiLookup", StrLookup.class));
107        } catch (final LinkageError | Exception e) {
108            handleError(LOOKUP_KEY_JNDI, e);
109        }
110        // JMX input args
111        try {
112            // We might be on Android
113            strLookupMap.put(LOOKUP_KEY_JVMRUNARGS,
114                Loader.newCheckedInstanceOf("org.apache.logging.log4j.core.lookup.JmxRuntimeInputArgumentsLookup",
115                        StrLookup.class));
116        } catch (final LinkageError | Exception e) {
117            handleError(LOOKUP_KEY_JVMRUNARGS, e);
118        }
119        strLookupMap.put("date", new DateLookup());
120        strLookupMap.put("ctx", new ContextMapLookup());
121        if (Constants.IS_WEB_APP) {
122            try {
123                strLookupMap.put(LOOKUP_KEY_WEB,
124                    Loader.newCheckedInstanceOf("org.apache.logging.log4j.web.WebLookup", StrLookup.class));
125            } catch (final Exception ignored) {
126                handleError(LOOKUP_KEY_WEB, ignored);
127            }
128        } else {
129            LOGGER.debug("Not in a ServletContext environment, thus not loading WebLookup plugin.");
130        }
131        try {
132            strLookupMap.put(LOOKUP_KEY_DOCKER,
133                Loader.newCheckedInstanceOf("org.apache.logging.log4j.docker.DockerLookup", StrLookup.class));
134        } catch (final Exception ignored) {
135            handleError(LOOKUP_KEY_DOCKER, ignored);
136        }
137    }
138
139    public Map<String, StrLookup> getStrLookupMap() {
140        return strLookupMap;
141    }
142
143    private void handleError(final String lookupKey, final Throwable t) {
144        switch (lookupKey) {
145            case LOOKUP_KEY_JNDI:
146                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JndiLookup
147                LOGGER.warn( // LOG4J2-1582 don't print the whole stack trace (it is just a warning...)
148                        "JNDI lookup class is not available because this JRE does not support JNDI." +
149                        " JNDI string lookups will not be available, continuing configuration. Ignoring " + t);
150                break;
151            case LOOKUP_KEY_JVMRUNARGS:
152                // java.lang.VerifyError: org/apache/logging/log4j/core/lookup/JmxRuntimeInputArgumentsLookup
153                LOGGER.warn(
154                        "JMX runtime input lookup class is not available because this JRE does not support JMX. " +
155                        "JMX lookups will not be available, continuing configuration. Ignoring " + t);
156                break;
157            case LOOKUP_KEY_WEB:
158                LOGGER.info("Log4j appears to be running in a Servlet environment, but there's no log4j-web module " +
159                        "available. If you want better web container support, please add the log4j-web JAR to your " +
160                        "web archive or server lib directory.");
161                break;
162            case LOOKUP_KEY_DOCKER:
163                break;
164            default:
165                LOGGER.error("Unable to create Lookup for {}", lookupKey, t);
166        }
167    }
168
169    /**
170     * Resolves the specified variable. This implementation will try to extract
171     * a variable prefix from the given variable name (the first colon (':') is
172     * used as prefix separator). It then passes the name of the variable with
173     * the prefix stripped to the lookup object registered for this prefix. If
174     * no prefix can be found or if the associated lookup object cannot resolve
175     * this variable, the default lookup object will be used.
176     *
177     * @param event The current LogEvent or null.
178     * @param var the name of the variable whose value is to be looked up
179     * @return the value of this variable or <b>null</b> if it cannot be
180     * resolved
181     */
182    @Override
183    public String lookup(final LogEvent event, String var) {
184        if (var == null) {
185            return null;
186        }
187
188        final int prefixPos = var.indexOf(PREFIX_SEPARATOR);
189        if (prefixPos >= 0) {
190            final String prefix = var.substring(0, prefixPos).toLowerCase(Locale.US);
191            final String name = var.substring(prefixPos + 1);
192            final StrLookup lookup = strLookupMap.get(prefix);
193            if (lookup instanceof ConfigurationAware) {
194                ((ConfigurationAware) lookup).setConfiguration(configuration);
195            }
196            String value = null;
197            if (lookup != null) {
198                value = event == null ? lookup.lookup(name) : lookup.lookup(event, name);
199            }
200
201            if (value != null) {
202                return value;
203            }
204            var = var.substring(prefixPos + 1);
205        }
206        if (defaultLookup != null) {
207            return event == null ? defaultLookup.lookup(var) : defaultLookup.lookup(event, var);
208        }
209        return null;
210    }
211
212    @Override
213    public String toString() {
214        final StringBuilder sb = new StringBuilder();
215        for (final String name : strLookupMap.keySet()) {
216            if (sb.length() == 0) {
217                sb.append('{');
218            } else {
219                sb.append(", ");
220            }
221
222            sb.append(name);
223        }
224        if (sb.length() > 0) {
225            sb.append('}');
226        }
227        return sb.toString();
228    }
229
230}