István Fajth created HADOOP-17975:
-------------------------------------
Summary: Fallback to simple auth does not work for a secondary
DistributedFileSystem instance
Key: HADOOP-17975
URL: https://issues.apache.org/jira/browse/HADOOP-17975
Project: Hadoop Common
Issue Type: Bug
Components: ipc
Reporter: István Fajth
Assignee: István Fajth
The following code snippet demonstrates what is necessary to cause a failure in
connection to a non secure cluster with fallback to SIMPLE auth allowed from a
secure cluster.
{code:java}
Configuration conf = new Configuration();
conf.setBoolean("ipc.client.fallback-to-simple-auth-allowed", true);
URI fsUri = new URI("hdfs://<nn_uri>");
conf.setBoolean("fs.hdfs.impl.disable.cache", true);
FileSystem fs = FileSystem.get(fsUri, conf);
FSDataInputStream src = fs.open(new Path("/path/to/a/file"));
FileOutputStream dst = new FileOutputStream(File.createTempFile("foo",
"bar"));
IOUtils.copyBytes(src, dst, 1024);
// The issue happens even if we re-enable cache at this point
//conf.setBoolean("fs.hdfs.impl.disable.cache", false);
// The issue does not happen when we close the first FileSystem object
// before creating the second.
//fs.close();
FileSystem fs2 = FileSystem.get(fsUri, conf);
FSDataInputStream src2 = fs2.open(new Path("/path/to/a/file"));
FileOutputStream dst2 = new FileOutputStream(File.createTempFile("foo",
"bar"));
IOUtils.copyBytes(src2, dst2, 1024);
{code}
The problem is that when the DfsClient is created it creates an instance of
AtomicBoolean, which is propagated down into the IPC layer, where the
Client.Connection instance in setupIOStreams sets its value. This connection
object is cached and re-used to multiplex requests against the same DataNode.
In case of creating a second DfsClient, the AtomicBoolean reference in the
client is a new AtomicBoolean, but the Client.Connection instance is the same,
and as it has a socket already open to the DataNode, it returns immediatelly
from setupIOStreams, leaving the fallbackToSimpleAuth AtomicBoolean false as it
is created in the DfsClient.
This AtomicBoolean on the other hand controls how the SaslDataTransferClient
handles the connection in the above level, and with this value left on the
default false, the SaslDataTransferClient of the second DfsClient will not fall
back to SIMPLE authentication but will try to send a SASL handshake when
connecting to the DataNode.
The access to the FileSystem via the second DfsClient fails with the following
exception:
{code}
WARN hdfs.DFSClient: Failed to connect to /<dn_ip>:<dn_port> for file <file>
for block BP-531773307-<nn_ip>-1634685133591:blk_1073741826_1002, add to
deadNodes and continue.
java.io.EOFException: Unexpected EOF while trying to read response from server
at
org.apache.hadoop.hdfs.protocolPB.PBHelperClient.vintPrefixed(PBHelperClient.java:552)
at
org.apache.hadoop.hdfs.protocol.datatransfer.sasl.DataTransferSaslUtil.readSaslMessage(DataTransferSaslUtil.java:215)
at
org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.doSaslHandshake(SaslDataTransferClient.java:455)
at
org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.getSaslStreams(SaslDataTransferClient.java:393)
at
org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.send(SaslDataTransferClient.java:267)
at
org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.checkTrustAndSend(SaslDataTransferClient.java:215)
at
org.apache.hadoop.hdfs.protocol.datatransfer.sasl.SaslDataTransferClient.peerSend(SaslDataTransferClient.java:160)
at
org.apache.hadoop.hdfs.DFSUtilClient.peerFromSocketAndKey(DFSUtilClient.java:648)
at
org.apache.hadoop.hdfs.DFSClient.newConnectedPeer(DFSClient.java:2980)
at
org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.nextTcpPeer(BlockReaderFactory.java:822)
at
org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.getRemoteBlockReaderFromTcp(BlockReaderFactory.java:747)
at
org.apache.hadoop.hdfs.client.impl.BlockReaderFactory.build(BlockReaderFactory.java:380)
at
org.apache.hadoop.hdfs.DFSInputStream.getBlockReader(DFSInputStream.java:658)
at
org.apache.hadoop.hdfs.DFSInputStream.blockSeekTo(DFSInputStream.java:589)
at
org.apache.hadoop.hdfs.DFSInputStream.readWithStrategy(DFSInputStream.java:771)
at org.apache.hadoop.hdfs.DFSInputStream.read(DFSInputStream.java:840)
at java.io.DataInputStream.read(DataInputStream.java:100)
at org.apache.hadoop.io.IOUtils.copyBytes(IOUtils.java:94)
at DfsClientTest3.main(DfsClientTest3.java:30)
{code}
The DataNode in the meantime logs the following:
{code}
ERROR org.apache.hadoop.hdfs.server.datanode.DataNode:
<dn_host>:<dn_port>:DataXceiver error processing unknown operation src:
/<client_ip>:<client_port> dst: /<dn_ip>:<dn_port>
java.io.IOException: Version Mismatch (Expected: 28, Received: -8531 )
at
org.apache.hadoop.hdfs.protocol.datatransfer.Receiver.readOp(Receiver.java:70)
at
org.apache.hadoop.hdfs.server.datanode.DataXceiver.run(DataXceiver.java:222)
at java.lang.Thread.run(Thread.java:748)
{code}
This happens only if the second client is connecting to the same DataNode as
the first one did, so might seem intermittent in case the clients are reading
different files, but happens always if the two client reads the same file with
replication factor 1.
We ran into this issue during running HBase ExportSnapshot tool to move a
snapshot from a non-secure to a secure cluster, the issue is loosely related to
HBASE-12819 and HBASE-20433 and similar problems, I am linking these so that
HBase team will see how this is relevant for them.
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