append operation in hadoop webhdfs client

Question

A Java client I threw together works:

import java.io.File;
import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.Path;

public class HdfsAppend {

        public static final String hdfs = "hdfs://my222host.com";
        public static final String hpath = "/tmp/odp/testfile";
        public static final String message = "Hello, world!\n";

        public static void main(String[] args) throws IOException {

                Configuration conf = new Configuration();
                conf.set("fs.defaultFS", hdfs);
                FileSystem fs = FileSystem.get(conf);
                Path filenamePath = new Path(hpath);

                FSDataOutputStream out = fs.append(filenamePath);
                out.writeBytes("DUPA DUPA DUPA\n");
        }
}

But both curl and Python whoops client fail in similar way, curl here:

curl -i -X POST   "http://my222host:50070/webhdfs/v1/tmp/odp/testfile?op=APPEND"
HTTP/1.1 307 TEMPORARY_REDIRECT
Cache-Control: no-cache
Expires: Tue, 13 Aug 2013 13:26:22 GMT
Date: Tue, 13 Aug 2013 13:26:22 GMT
Pragma: no-cache
Expires: Tue, 13 Aug 2013 13:26:22 GMT
Date: Tue, 13 Aug 2013 13:26:22 GMT
Pragma: no-cache
Content-Type: application/octet-stream
Location: http://my333host:50075/webhdfs/v1/tmp/odp/testfile?op=APPEND&namenoderpcaddress=my222host:8020
Content-Length: 0
Server: Jetty(6.1.26.cloudera.2)


curl -i -X POST -T /tmp/abc "http://my333host:50075/webhdfs/v1/tmp/odp/testfile?op=APPEND&namenoderpcaddress=my222host:8020"
HTTP/1.1 100 Continue

HTTP/1.1 403 Forbidden
Cache-Control: no-cache
Expires: Tue, 13 Aug 2013 13:26:26 GMT
Date: Tue, 13 Aug 2013 13:26:26 GMT
Pragma: no-cache
Expires: Tue, 13 Aug 2013 13:26:26 GMT
Date: Tue, 13 Aug 2013 13:26:26 GMT
Pragma: no-cache
Content-Type: application/json
Transfer-Encoding: chunked
Server: Jetty(6.1.26.cloudera.2)

{"RemoteException":{"exception":"AccessControlException","javaClassName":"org.apache.hadoop.security.AccessControlException","message":"Permission denied: user=dr.who, access=WRITE, inode=\"/tmp/odp/testfile\":root:hadoop:-rw-r--r--\n\tat org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:224)\n\tat org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:155)\n\tat org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4716)\n\tat org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4698)\n\tat org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPathAccess(FSNamesystem.java:4660)\n\tat org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:1837)\n\tat org.apache.hadoop.hdfs.server.namenode.FSNamesystem.appendFileInt(FSNamesystem.java:2105)\n\tat org.apache.hadoop.hdfs.server.namenode.FSNamesystem.appendFile(FSNamesystem.java:2081)\n\tat org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.append(NameNodeRpcServer.java:434)\n\tat org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.append(ClientNamenodeProtocolServerSideTranslatorPB.java:224)\n\tat org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java:44944)\n\tat org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:453)\n\tat org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1002)\n\tat org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1701)\n\tat org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1697)\n\tat java.security.AccessController.doPrivileged(Native Method)\n\tat javax.security.auth.Subject.doAs(Subject.java:396)\n\tat org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1408)\n\tat org.apache.hadoop.ipc.Server$Handler.run(Server.java:1695)\n"}}

whoops client fails with "connection refused". What can be the problem here? The only clue I have is "user=dr.who" in java exception when using curl, but I have no idea what is the user used by Configuration class or how to get it (if that is the root of the problem). Pls help!

Answer 1

Assuming your user name is hdfs, add &user.name=hdfs to your URL. Write operations require a valid user.

Your java code works because it pulls your user information from the unix environment.

If you see the user dr.who anywhere, it's probably because you haven't set a user.name in your request.