    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 *      https://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 */
    017
    018package org.apache.commons.lang3;
    019
    020import java.io.IOException;
    021import java.nio.charset.Charset;
    022import java.nio.file.Files;
    023import java.nio.file.Paths;
    024import java.util.Arrays;
    025
    026/**
    027 * Helps query the runtime environment.
    028 *
    029 * @since 3.15.0
    030 */
    031public class RuntimeEnvironment {
    032
    033    private static boolean fileExists(final String path) {
    034        return Files.exists(Paths.get(path));
    035    }
    036
    037    /**
    038     * Tests whether we are running in a container like Docker or Podman.
    039     * <p>
    040     * <em>The following may change if we find better detection logic.</em>
    041     * </p>
    042     * <p>
    043     * We roughly follow the logic in SystemD:
    044     * </p>
    045     * <p>
    046     * <a href=
    047     * "https://github.com/systemd/systemd/blob/0747e3b60eb4496ee122066c844210ce818d76d9/src/basic/virt.c#L692">https://github.com/systemd/systemd/blob/0747e3b60eb4496ee122066c844210ce818d76d9/src/basic/virt.c#L692</a>
    048     * </p>
    049     * <p>
    050     * We check the `container` environment variable of process 1:
    051     * </p>
    052     * <ol>
    053     * <li>If the variable is empty, we return false. This includes the case, where the container developer wants to hide the fact that the application runs in
    054     * a container.</li>
    055     * <li>If the variable is not empty, we return true.</li>
    056     * <li>If the variable is absent, we continue.</li>
    057     * <li>We check files in the container. According to SystemD:/
    058     * <ol>
    059     * <li>/.dockerenv is used by Docker.</li>
    060     * <li>/run/.containerenv is used by PodMan.</li>
    061     * </ol>
    062     * </li>
    063     * </ol>
    064     *
    065     * @return whether we are running in a container like Docker or Podman. Never null.
    066     * @see <a href="https://github.com/systemd/systemd/blob/0747e3b60eb4496ee122066c844210ce818d76d9/src/basic/virt.c#L692">SystemD virt.c</a>
    067     */
    068    public static Boolean inContainer() {
    069        return inContainer(StringUtils.EMPTY);
    070    }
    071
    072    /**
    073     * Tests whether we are running in a container like Docker or Podman.
    074     * <p>
    075     * <em>The following may change if we find better detection logic.</em>
    076     * </p>
    077     * <p>
    078     * We roughly follow the logic in SystemD:
    079     * </p>
    080     * <p>
    081     * <a href=
    082     * "https://github.com/systemd/systemd/blob/0747e3b60eb4496ee122066c844210ce818d76d9/src/basic/virt.c#L692">https://github.com/systemd/systemd/blob/0747e3b60eb4496ee122066c844210ce818d76d9/src/basic/virt.c#L692</a>
    083     * </p>
    084     * <p>
    085     * We check the `container` environment variable of process 1:
    086     * </p>
    087     * <ol>
    088     * <li>If the variable is empty, we return false. This includes the case, where the container developer wants to hide the fact that the application runs in
    089     * a container.</li>
    090     * <li>If the variable is not empty, we return true.</li>
    091     * <li>If the variable is absent, we continue.</li>
    092     * <li>We check files in the container. According to SystemD:/
    093     * <ol>
    094     * <li>/.dockerenv is used by Docker.</li>
    095     * <li>/run/.containerenv is used by PodMan.</li>
    096     * </ol>
    097     * </li>
    098     * </ol>
    099     *
    100     * @return Whether we are running in a container like Docker or Podman.
    101     * @see <a href="https://github.com/systemd/systemd/blob/0747e3b60eb4496ee122066c844210ce818d76d9/src/basic/virt.c#L692">SystemD virt.c</a>
    102     */
    103    static boolean inContainer(final String dirPrefix) {
    104        final String value = readFile(dirPrefix + "/proc/1/environ", "container");
    105        if (value != null) {
    106            return !value.isEmpty();
    107        }
    108        return fileExists(dirPrefix + "/.dockerenv") || fileExists(dirPrefix + "/run/.containerenv");
    109    }
    110
    111    /**
    112     * Tests whether the {@code /proc/N/environ} file at the given path string contains a specific line prefix.
    113     *
    114     * @param envVarFile The path to a /proc/N/environ file.
    115     * @param key        The env var key to find.
    116     * @return value The env var value or null.
    117     */
    118    private static String readFile(final String envVarFile, final String key) {
    119        try {
    120            final byte[] bytes = Files.readAllBytes(Paths.get(envVarFile));
    121            final String content = new String(bytes, Charset.defaultCharset());
    122            // Split by null byte character
    123            final String[] lines = content.split(String.valueOf(CharUtils.NUL));
    124            final String prefix = key + "=";
    125            // @formatter:off
    126            return Arrays.stream(lines)
    127                    .filter(line -> line.startsWith(prefix))
    128                    .map(line -> line.split("=", 2))
    129                    .map(keyValue -> keyValue[1])
    130                    .findFirst()
    131                    .orElse(null);
    132            // @formatter:on
    133        } catch (final IOException e) {
    134            return null;
    135        }
    136    }
    137
    138    /**
    139     * Constructs a new instance.
    140     *
    141     * @deprecated Will be removed in 4.0.0.
    142     */
    143    @Deprecated
    144    public RuntimeEnvironment() {
    145        // empty
    146    }
    147}