Lazy init of fullyQualifiedStorageDirectory in HDFS pusher (#5684)

* Lazy init of fullyQualifiedStorageDirectory in HDFS pusher

* Comment

* Fix test

* PR comments

extensions-core/hdfs-storage/src/main/java/io/druid/storage/hdfs/HdfsDataSegmentPusher.java

@@ -20,6 +20,8 @@
 package io.druid.storage.hdfs;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.google.common.base.Supplier;
+import com.google.common.base.Suppliers;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.io.ByteSink;
 import com.google.common.io.ByteSource;
@@ -53,7 +55,10 @@ public class HdfsDataSegmentPusher implements DataSegmentPusher
 
   private final Configuration hadoopConfig;
   private final ObjectMapper jsonMapper;
-  private final String fullyQualifiedStorageDirectory;
+
+  // We lazily initialize fullQualifiedStorageDirectory to avoid potential issues with Hadoop namenode HA.
+  // Please see https://github.com/druid-io/druid/pull/5684
+  private final Supplier<String> fullyQualifiedStorageDirectory;
 
   @Inject
   public HdfsDataSegmentPusher(
@@ -65,10 +70,19 @@ public class HdfsDataSegmentPusher implements DataSegmentPusher
     this.hadoopConfig = hadoopConfig;
     this.jsonMapper = jsonMapper;
     Path storageDir = new Path(config.getStorageDirectory());
-    this.fullyQualifiedStorageDirectory = FileSystem.newInstance(storageDir.toUri(), hadoopConfig)
+    this.fullyQualifiedStorageDirectory = Suppliers.memoize(
+        () -> {
+          try {
+            return FileSystem.newInstance(storageDir.toUri(), hadoopConfig)
                              .makeQualified(storageDir)
                              .toUri()
                              .toString();
+          }
+          catch (Exception e) {
+            throw new RuntimeException(e);
+          }
+        }
+    );
 
     log.info("Configured HDFS as deep storage");
   }
@@ -83,7 +97,7 @@ public class HdfsDataSegmentPusher implements DataSegmentPusher
   @Override
   public String getPathForHadoop()
   {
-    return fullyQualifiedStorageDirectory;
+    return fullyQualifiedStorageDirectory.get();
   }
 
   @Override
@@ -94,13 +108,13 @@ public class HdfsDataSegmentPusher implements DataSegmentPusher
     log.info(
         "Copying segment[%s] to HDFS at location[%s/%s]",
         segment.getIdentifier(),
-        fullyQualifiedStorageDirectory,
+        fullyQualifiedStorageDirectory.get(),
         storageDir
     );
 
     Path tmpIndexFile = new Path(StringUtils.format(
         "%s/%s/%s/%s_index.zip",
-        fullyQualifiedStorageDirectory,
+        fullyQualifiedStorageDirectory.get(),
         segment.getDataSource(),
         UUIDUtils.generateUuid(),
         segment.getShardSpec().getPartitionNum()
@@ -116,13 +130,13 @@ public class HdfsDataSegmentPusher implements DataSegmentPusher
       size = CompressionUtils.zip(inDir, out);
       final Path outIndexFile = new Path(StringUtils.format(
           "%s/%s/%d_index.zip",
-          fullyQualifiedStorageDirectory,
+          fullyQualifiedStorageDirectory.get(),
           storageDir,
           segment.getShardSpec().getPartitionNum()
       ));
       final Path outDescriptorFile = new Path(StringUtils.format(
           "%s/%s/%d_descriptor.json",
-          fullyQualifiedStorageDirectory,
+          fullyQualifiedStorageDirectory.get(),
           storageDir,
           segment.getShardSpec().getPartitionNum()
       ));

extensions-core/hdfs-storage/src/test/java/io/druid/storage/hdfs/HdfsDataSegmentPusherTest.java

@@ -107,7 +107,7 @@ public class HdfsDataSegmentPusherTest
   @Test
   public void testPushWithBadScheme() throws Exception
   {
-    expectedException.expect(IOException.class);
+    expectedException.expect(RuntimeException.class);
     expectedException.expectMessage("No FileSystem for scheme");
     testUsingScheme("xyzzy");