in the plugin: guard against HADOOP_HOME in environment on any platform.

hdfs fixture: minihdfs works on windows now, if things are properly set
but our test fixture still cannot launch this on windows.

plugins/repository-hdfs/build.gradle

@@ -18,6 +18,11 @@
  */
 
 //apply plugin: 'nebula.provided-base'
+
+import org.apache.tools.ant.taskdefs.condition.Os
+import java.nio.file.Files
+import java.nio.file.Path
+import java.nio.file.Paths
  
 esplugin {
   description 'The HDFS repository plugin adds support for Hadoop Distributed File-System (HDFS) repositories.'
@@ -65,16 +70,34 @@ task hdfsFixture(type: org.elasticsearch.gradle.test.Fixture) {
 }
 
 integTest {
-  // hdfs fixture will not start without hadoop native libraries on windows
-  // so we can't run integration tests against external hadoop here.
-  if (System.getProperty("os.name").startsWith("Windows")) {
+  boolean fixtureSupported = false;
+  if (Os.isFamily(Os.FAMILY_WINDOWS)) {
+    // hdfs fixture will not start without hadoop native libraries on windows
+    String nativePath = System.getenv("HADOOP_HOME")
+    if (nativePath != null) {
+      Path path = Paths.get(nativePath);
+      if (Files.isDirectory(path) &&
+          Files.exists(path.resolve("bin").resolve("winutils.exe")) &&
+          Files.exists(path.resolve("bin").resolve("hadoop.dll")) &&
+          Files.exists(path.resolve("bin").resolve("hdfs.dll"))) {
+        fixtureSupported = true
+      } else {
+        throw new IllegalStateException("HADOOP_HOME: " + path.toString() + " is invalid, does not contain hadoop native libraries in $HADOOP_HOME/bin");
+      }
+    }
+  } else {
+    fixtureSupported = true
+  }
+
+  if (fixtureSupported) {
+    dependsOn hdfsFixture
+  } else {
+    logger.warn("hdfsFixture unsupported, please set HADOOP_HOME and put HADOOP_HOME\\bin in PATH")
     systemProperty 'tests.rest.blacklist', [
       'hdfs_repository/20_repository/*',
       'hdfs_repository/30_snapshot/*',
       'hdfs_repository/40_restore/*'
     ].join(',')
-  } else {
-    dependsOn hdfsFixture
   }
 }
 

plugins/repository-hdfs/src/main/java/org/elasticsearch/plugin/hadoop/hdfs/HdfsPlugin.java

@@ -54,14 +54,14 @@ public class HdfsPlugin extends Plugin {
     private static Void evilHadoopInit() {
         // hack: on Windows, Shell's clinit has a similar problem that on unix,
         // but here we can workaround it for now by setting hadoop home
+        // on unix: we still want to set this to something we control, because
+        // if the user happens to have HADOOP_HOME in their environment -> checkHadoopHome goes boom
         // TODO: remove THIS when hadoop is fixed
         Path hadoopHome = null;
         String oldValue = null;
         try {
-            if (Constants.WINDOWS) {
-                hadoopHome = Files.createTempDirectory("hadoop").toAbsolutePath();
-                oldValue = System.setProperty("hadoop.home.dir", hadoopHome.toString());
-            }
+            hadoopHome = Files.createTempDirectory("hadoop").toAbsolutePath();
+            oldValue = System.setProperty("hadoop.home.dir", hadoopHome.toString());
             Class.forName("org.apache.hadoop.security.UserGroupInformation");
             Class.forName("org.apache.hadoop.util.StringUtils");
             Class.forName("org.apache.hadoop.util.ShutdownHookManager");
@@ -69,19 +69,17 @@ public class HdfsPlugin extends Plugin {
             throw new RuntimeException(e);
         } finally {
             // try to clean up the hack
-            if (Constants.WINDOWS) {
-                if (oldValue == null) {
-                    System.clearProperty("hadoop.home.dir");
-                } else {
-                    System.setProperty("hadoop.home.dir", oldValue);
-                }
-                try {
-                    // try to clean up our temp dir too if we can
-                    if (hadoopHome != null) {
-                       Files.delete(hadoopHome);
-                    }
-                } catch (IOException thisIsBestEffort) {}
+            if (oldValue == null) {
+                System.clearProperty("hadoop.home.dir");
+            } else {
+                System.setProperty("hadoop.home.dir", oldValue);
             }
+            try {
+                // try to clean up our temp dir too if we can
+                if (hadoopHome != null) {
+                    Files.delete(hadoopHome);
+                }
+            } catch (IOException thisIsBestEffort) {}
         }
         return null;
     }

test/fixtures/hdfs-fixture/src/main/java/hdfs/MiniHDFS.java

@@ -49,9 +49,11 @@ public class MiniHDFS {
         // configure Paths
         Path baseDir = Paths.get(args[0]);
         // hadoop-home/, so logs will not complain
-        Path hadoopHome = baseDir.resolve("hadoop-home");
-        Files.createDirectories(hadoopHome);
-        System.setProperty("hadoop.home.dir", hadoopHome.toAbsolutePath().toString());
+        if (System.getenv("HADOOP_HOME") == null) {
+            Path hadoopHome = baseDir.resolve("hadoop-home");
+            Files.createDirectories(hadoopHome);
+            System.setProperty("hadoop.home.dir", hadoopHome.toAbsolutePath().toString());
+        }
         // hdfs-data/, where any data is going
         Path hdfsHome = baseDir.resolve("hdfs-data");