Hi All,
I’m trying to access HDFS on behalf of another user. I’m trying this with the
following application
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.log4j.Logger;
import org.apache.hadoop.fs.FSDataOutputStream;
import java.security.PrivilegedExceptionAction;
public class HDFSProxyTest {
public static void main (String[] args) throws Exception {
String hadoopConfigurationPath = "/etc/hadoop/conf/";
final Configuration hdfsConfiguration = new Configuration();
FileSystem localFileSystem = FileSystem.getLocal(hdfsConfiguration);
Path coreSitePath = new Path(hadoopConfigurationPath+"core-site.xml");
hdfsConfiguration.addResource(coreSitePath);
Path hdfsSitePath = new Path(hadoopConfigurationPath+"hdfs-site.xml");
hdfsConfiguration.addResource(hdfsSitePath);
UserGroupInformation.setConfiguration(hdfsConfiguration);
UserGroupInformation.loginUserFromKeytab("[email protected]",
"/home/striim/striim1_client.keytab");
UserGroupInformation ugi =
UserGroupInformation.createProxyUser("joy",
UserGroupInformation.getLoginUser());
FileSystem hadoopFileSystem =ugi.doAs(new
PrivilegedExceptionAction<FileSystem>() {
public FileSystem run() throws Exception {
return FileSystem.get(hdfsConfiguration);
}
});
FSDataOutputStream fsDataOutputStream = hadoopFileSystem.create(new
Path("/user/striim1/hdfsproxy.csv"));
fsDataOutputStream.write("This is niranjan!!! testing
this\n".getBytes());
fsDataOutputStream.close();
hadoopFileSystem.close();
}
}
Here this app execution user is striim and the super user I’m trying to emulate
is striim1 who has Kerberos credentials and joy is the user on whose behalf I’m
trying to access HDFS.
I end up with this exception.
2017-05-19 02:45:34,843 - WARN main
org.apache.hadoop.util.NativeCodeLoader.<clinit> (NativeCodeLoader.java:62)
Unable to load native-hadoop library for your platform... using builtin-java
classes where applicable
Exception in thread "main" org.apache.hadoop.security.AccessControlException:
Permission denied: user=joy, access=WRITE,
inode="/user/striim1":striim1:striim1:drwxr-xr-x
at
org.apache.hadoop.hdfs.server.namenode.DefaultAuthorizationProvider.checkFsPermission(DefaultAuthorizationProvider.java:281)
at
org.apache.hadoop.hdfs.server.namenode.DefaultAuthorizationProvider.check(DefaultAuthorizationProvider.java:262)
at
org.apache.hadoop.hdfs.server.namenode.DefaultAuthorizationProvider.check(DefaultAuthorizationProvider.java:242)
at
org.apache.hadoop.hdfs.server.namenode.DefaultAuthorizationProvider.checkPermission(DefaultAuthorizationProvider.java:169)
at
org.apache.sentry.hdfs.SentryAuthorizationProvider.checkPermission(SentryAuthorizationProvider.java:178)
at
org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:152)
at
org.apache.hadoop.hdfs.server.namenode.FSDirectory.checkPermission(FSDirectory.java:3560)
at
org.apache.hadoop.hdfs.server.namenode.FSDirectory.checkPermission(FSDirectory.java:3543)
at
org.apache.hadoop.hdfs.server.namenode.FSDirectory.checkAncestorAccess(FSDirectory.java:3525)
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkAncestorAccess(FSNamesystem.java:6592)
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInternal(FSNamesystem.java:2821)
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFileInt(FSNamesystem.java:2739)
at
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.startFile(FSNamesystem.java:2624)
at
org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.create(NameNodeRpcServer.java:599)
at
org.apache.hadoop.hdfs.server.namenode.AuthorizationProviderProxyClientProtocol.create(AuthorizationProviderProxyClientProtocol.java:112)
at
org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.create(ClientNamenodeProtocolServerSideTranslatorPB.java:401)
at
org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
at
org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:617)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1073)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2141)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2137)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at
org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1714)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2135)
This is my configuration on core-site.xml
<property>
<name>hadoop.proxyuser.striim1.hosts</name>
<value>*</value>
</property>
<property>
<name>hadoop.proxyuser.striim1.groups</name>
<value>*</value>
</property>
This is the permission setting of folder I’m trying to access
drwxr-xr-x - striim1 striim1 0 2017-05-19 02:50
/user/striim1
I need explanation for the following questions
1) Even though I pass super user’s UGI to the proxy user joy. Why is the client
trying to create the file in the context of user joy?
2) In my cluster deployment, “striim1” is just a user who has Kerberos
credentials and not really a super-user as per this definition. Would
impersonation work only if “striim1” is a superuser or added to the group of
super user?
3) Should the name of the user I’m trying to impersonate be a valid OS user? If
not what would happen and what validation is done in this respect?
4) What should be the permission setting of directory I’m trying to write using
this impersonated user? Should be it some location that is owned or part of
super-user group?
5) Should UGI.createProxyUser be called explicitly in my application? Say I
execute my application from the user whom I want to impersonate using
super-user and I pass proxy user configuration (basically passing core-site.xm)
to my application? Would this suffice? (l’m expecting something like
createProxyUser being called internally by taking current app executing user as
the user to be impersonated).
Also in general let me know other internals of how this User impersonation
works. I want to understand this well and I’m interested in knowing the answers
of these 5 questions.
Thanks in advance.
Regards,
Niranjan
