unable to start start-dfs.sh in Hadoop Multinode cluster - hadoop

I have created a hadoop multinode cluster and also configured SSH in both master and slave nodes now i can connect to slave without password in master node
But when i try to start-dfs.sh in master node I'm unable to connect to slave node the execution stops at below line
log:
HNname#master:~$ start-all.sh
starting namenode, logging to /usr/local/hadoop/libexec/../logs/hadoop-HNname-namenode-master.out
HDnode#slave's password: master: starting datanode, logging to /usr/local/hadoop/libexec/../logs/hadoop-HNname-datanode-master.out
I pressed Enter
slave: Connection closed by 192.168.0.2
master: starting secondarynamenode, logging to /usr/local/hadoop/libexec/../logs/hadoop-HNname-secondarynamenode-master.out
jobtracker running as process 10396. Stop it first.
HDnode#slave's password: master: starting tasktracker, logging to /usr/local/hadoop/libexec/../logs/hadoop-HNname-tasktracker-master.out
slave: Permission denied, please try again.
HDnode#slave's password:
after entering the slave password the connection is closed
Below things I have tried but no results:
formatted namenode in both master & slave node
created new ssh key and configured in both the nodes
override the default HADOOP_LOG_DIR form the this post

I think you missed this step "Add the SSH Public Key to the authorized_keys file on your target hosts"
Just redo the password-less ssh step correctly. Follow this:
Generate public and private SSH keys
ssh-keygen
Copy the SSH Public Key (id_rsa.pub) to the root account on your
target hosts
.ssh/id_rsa
.ssh/id_rsa.pub
Add the SSH Public Key to the authorized_keys file on your target
hosts
cat id_rsa.pub >> authorized_keys
Depending on your version of SSH, you may need to set permissions on
the .ssh directory (to 700) and the authorized_keys file in that
directory (to 600) on the target hosts.
chmod 700 ~/.ssh
chmod 600 ~/.ssh/authorized_keys
Check the connection:
ssh root#<remote.target.host>
where <remote.target.host> has the value of each host name in your cluster.
If the following warning message displays during your first
connection: Are you sure you want to continue connecting (yes/no)?
Enter Yes.
Refer: Set Up Password-less SSH
Note: password will not be asked, if your passwordless ssh is setup properly.

Make sure to start hadoop services with a new user called hadoop.
Then make sure to add the public key to the slaves with that new user.
If this doesn't work, check your firewall or iptables
I hope it helps

That mean you haven't created public key properly.
Follow below sequence.
Create User
Give all required permissions to that user
Generate public key with same user
Format Name Node
Start hadoop services.
Now it should not ask for password.

Related

Hadoop nodes do not ask for passwords during start

When I try to ssh into localhost, I am prompted for password. See below
"
ssh connection to localhost:
[hadoop#mftrhel74 sbin]$ ssh localhost
hadoop#localhost's password:
Last login: Fri Aug 23 15:44:08 2019 from mah"
---The above statement means, passwordless connection is not setup----
But when I try to start Hadoop nodes as below, it doesn't prompt for password.
And the nodes are not starting, I see below message
I think it should prompt me to enter the password for the user just like as SSH connection is to be established.
[hadoop#mftrhel74 ~]$ start-dfs.sh
Starting namenodes on [mftrhel74]
mftrhel74: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
Starting datanodes
localhost: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
Starting secondary namenodes [mftrhel74]
mftrhel74: Permission denied (publickey,gssapi-keyex,gssapi-with-mic,password).
************I DO NOT WANT A PASSWORDLESS CONNECTION*****
I suspect you are able to log in to one of the nodes with SSH, however probably you have not set up passwordless ssh between the nodes, so the steps you try to execute from the node will fail.
Here is some documentation that should explain that you need to set up passwordless ssh or otherwise install an ambari client (assuming you work on HDP).
https://ambari.apache.org/1.2.2/installing-hadoop-using-ambari/content/ambari-chap1-5-2.html

Must the username of NameNode be equal to DataNode's?

I run namenode with user hduser#master, datanodes are running with user1#slave1, user1#slave2. Setting up SSh keys works fine, I can ssh remotely to my DataNode machines from master.
However, when I try to run the hadoop-daemons.sh for my datanodes it fails because it tries to ssh with the wrong user:
hduser#master:~$ hadoop-daemons.sh start datanode
hduser#slave3's password: hduser#slave1's password: hduser#slave2's password:
slave1: Permission denied (publickey,password).
slave2: Permission denied (publickey,password).
slave3: Permission denied (publickey,password).
I tried to reset the public and private key for my master and copying it to the data nodes
$ ssh-keygen -t rsa -P ""
$ ssh-copy-id -i $HOME/.ssh/id_rsa.pub user1#slave1
But gives me same error.
Does the user on the NameNode need to be the same as for the DataNodes?
Answer: After resetting the VMs and adding same user and installing Hadoop on the Data Nodes with the same user as for Name Node, it worked. So I guess the answer is yes...

Hadoop Multinode Cluster, slave permission denied

I'm trying to do multinode cluster (actually with 2 nodes - 1 master and 1 slave) on Hadoop. I follow the instruction Multinode Cluster for Hadoop 2.x
When I execute the order:
./sbin/start-all.sh
I got the error message for my slave node:
slave: Permission denied (publickey)
I already modified both .ssh/authorized_keys files on master and slave and add the keyprint from .ssh/id_rsa.pub from master and slave.
Finally I restarted the ssh with the next command sudo service ssh restart also on the both nodes (master and slaves).
By the executing of the order ./sbin/start-all.sh I don't have a problem with the master node, but slave node get me back the error message permission denied.
Has anybody some ideas, why I can not see the slave node?
The execution of the jps order get me currently next result:
master
18339 Jps
17717 SecondaryNameNode
18022 NodeManager
17370 NameNode
17886 ResourceManager
slave
2317 Jps
I think, master is ok, but I have troubles with slave.
After ssh-keygen on the Master. Copy the id_rsa.pub to the authorized_keys using cat id_rsa.pub >> authorized_keys on all the slaves. Test the password-less ssh using:
ssh <slave_node_IP>
if you have copied the whole hadoop folder from master to slave nodes(for easy replication), make sure that the slave node's hadoop folder has the correct owner from the slave system.
chown * 777 <slave's username> </path/to/hadoop>
I ran this command on my slave system and it solved my problem.

Passwordless SSH not establishing

I am trying to install Hadoop on Amazon EC2 Instance CentOS 6.5.I am connected to the instance but want to make the session passwordless SSH. To do this I used the following commands:
ssh-keygen
ssh-copy-id -i ~/.ssh/id_rsa.pub node01
I get an error saying : Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
I tried logging in as "root" as well as "ec2-user" but it shows the same error.
Could anyone help on this.
I have created a simple scriptlet to ease this process on EC2 - Ubuntu instances.
You can check it out here.
Just give the machine names and key path, you are done!
https://github.com/hshinde/pwless

how to restart hadoop cluster on emr

I have a hadoop installation on the Amazon Elastic MapReduce , whenever I try to restart the cluster I get the following error:
/stop-all.sh
no jobtracker to stop
The authenticity of host 'localhost (::1)' can't be established. RSA key fingerprint is
Are you sure you want to continue connecting (yes/no)? yes
localhost: Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
localhost: Permission denied (publickey).
no namenode to stop
localhost: Permission denied (publickey).
localhost: Permission denied (publickey).
Any idea on how to restart hadoop?
Following hack worked for me.
I have replaced "ssh" command in sbin/slaves.sh & sbin/hadoop-daemon.sh with "ssh -i ~/.ssh/keyname"
I'm using hadoop version 2.4 and this worked for me:
export HADOOP_SSH_OPTS="-i /home/hadoop/mykey.pem"
For the stop-all.sh script to work, you probably need to have the same user in all the machines as the user with which you are executing the stop-all.sh script.
Moreover, it seems you do not have a password less ssh setup from the machine you are executing stop-all.sh to rest of the machines that will spare you from manually entering the password for each machine separately. Passwords might be different for the same user for different machines, please don't forget that.

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