Fix broken detection of mvnd home on alpine linux (fixes #849) (#848)

* Fix for musl dynamic loader
* Add caching for mvnd.home and java.home
* Add IT for alpine linux

client/src/main/java/org/mvndaemon/mvnd/client/DaemonParameters.java

@@ -111,6 +111,7 @@ public class DaemonParameters {
                 .orLocalProperty(provider, userPropertiesPath())
                 .orEnvironmentVariable()
                 .orFail()
+                .cache(provider)
                 .asPath()
                 .toAbsolutePath()
                 .normalize();
@@ -119,7 +120,25 @@ public class DaemonParameters {
     private String mvndHomeFromExecutable() {
         Optional<String> cmd = ProcessHandle.current().info().command();
         if (Environment.isNative() && cmd.isPresent()) {
-            final Path mvndH = Paths.get(cmd.get()).getParent().getParent();
+            String cmdStr = cmd.get();
+            // When running on alpine, musl uses a dynamic loader
+            // which is used as the main exec and the full path to the
+            // executable is the argument following "--"
+            if (cmdStr.startsWith("/lib/ld-musl-")) {
+                Optional<String[]> args = ProcessHandle.current().info().arguments();
+                if (args.isPresent()) {
+                    boolean nextIsArg0 = false;
+                    for (String arg : args.get()) {
+                        if (nextIsArg0) {
+                            cmdStr = arg;
+                            break;
+                        } else {
+                            nextIsArg0 = "--".equals(arg);
+                        }
+                    }
+                }
+            }
+            Path mvndH = Paths.get(cmdStr).getParent().getParent();
             if (mvndH != null) {
                 Path mvndDaemon =
                         Paths.get("mvnd-daemon-" + BuildProperties.getInstance().getVersion() + ".jar");
@@ -143,6 +162,7 @@ public class DaemonParameters {
                 .or(new ValueSource(
                         description -> description.append("java command"), DaemonParameters::javaHomeFromPath))
                 .orFail()
+                .cache(provider)
                 .asPath();
         try {
             return result.toRealPath();
@@ -698,5 +718,20 @@ public class DaemonParameters {
                 throw couldNotgetValue();
             }
         }
+
+        public EnvValue cache(Function<Path, Properties> provider) {
+            return new EnvValue(this, envKey, new ValueSource(sb -> sb, () -> null)) {
+                @Override
+                String get() {
+                    Properties props = provider.apply(Paths.get(DaemonParameters.class.getName() + "#cache"));
+                    String value = props.getProperty(envKey.getProperty());
+                    if (value == null) {
+                        value = super.get();
+                        props.setProperty(envKey.getProperty(), value);
+                    }
+                    return value;
+                }
+            };
+        }
     }
 }

integration-tests/pom.xml

@@ -94,6 +94,18 @@
       <artifactId>commons-compress</artifactId>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.testcontainers</groupId>
+      <artifactId>testcontainers</artifactId>
+      <version>1.18.1</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.testcontainers</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>1.18.1</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

integration-tests/src/test/java/org/mvndaemon/mvnd/it/AlpineLinuxNativeIT.java

@@ -0,0 +1,70 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.mvndaemon.mvnd.it;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.api.condition.DisabledOnOs;
+import org.junit.jupiter.api.condition.OS;
+import org.testcontainers.containers.GenericContainer;
+import org.testcontainers.images.builder.ImageFromDockerfile;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+@Testcontainers(disabledWithoutDocker = true)
+public class AlpineLinuxNativeIT {
+
+    private ImageFromDockerfile image;
+    private String mvndHome;
+
+    @BeforeAll
+    void createImage() {
+        image = new ImageFromDockerfile()
+                .withDockerfileFromBuilder(builder -> builder.from("bellsoft/liberica-openjdk-alpine-musl:latest")
+                        .run("apk add gcompat")
+                        .build());
+        mvndHome = System.getProperty("mvnd.home");
+        if (mvndHome == null) {
+            throw new IllegalStateException("System property mnvd.home is undefined");
+        }
+    }
+
+    @Test
+    @DisabledOnOs(OS.WINDOWS)
+    void testAlpineJvm() throws Exception {
+        String logs;
+        try (GenericContainer<?> alpine = new GenericContainer<>(image)
+                .withFileSystemBind(mvndHome, "/mvnd")
+                .withCommand(isNative() ? "/mvnd/bin/mvnd" : "/mvnd/bin/mvnd.sh", "-v")) {
+            alpine.start();
+            while (alpine.isRunning()) {
+                Thread.sleep(100);
+            }
+            logs = alpine.getLogs();
+        }
+        assertTrue(logs.contains("Apache Maven Daemon"), logs);
+    }
+
+    protected boolean isNative() {
+        return true;
+    }
+}

integration-tests/src/test/java/org/mvndaemon/mvnd/it/AlpineLinuxTest.java

@@ -0,0 +1,32 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.mvndaemon.mvnd.it;
+
+import org.junit.jupiter.api.TestInstance;
+import org.testcontainers.junit.jupiter.Testcontainers;
+
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+@Testcontainers(disabledWithoutDocker = true)
+public class AlpineLinuxTest extends AlpineLinuxNativeIT {
+
+    @Override
+    protected boolean isNative() {
+        return false;
+    }
+}