[jira] [Commented] (ZOOKEEPER-851) ZK lets any node to become an observer

["Vishal Kathuria (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-851?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13095436#comment-13095436 ] 

Vishal Kathuria commented on ZOOKEEPER-851:
-------------------------------------------

Vishal -
I am actually using this behavior as a feature to add observers on demand without having to restart the core ensemble. It is slightly different from the scenario you tried. In my scenario, the 4th node thinks it is an observer (instead of it being a participant). Could you please make sure that the unknown observer scenario works fine with your patch? From what I could tell from reviewing the patch, even an unknown observer will get an INVALID_PEER message.

Thanks!
Vishal (FB) 

> ZK lets any node to become an observer
> --------------------------------------
>
>                 Key: ZOOKEEPER-851
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-851
>             Project: ZooKeeper
>          Issue Type: Bug
>          Components: quorum, server
>    Affects Versions: 3.3.1
>            Reporter: Vishal Kher
>            Assignee: Laxman
>            Priority: Critical
>             Fix For: 3.4.0, 3.5.0
>
>         Attachments: ZOOKEEPER-851.patch
>
>
> I had a 3 node cluster running. The zoo.cfg on each contained 3 entries as show below:
> tickTime=2000
> dataDir=/var/zookeeper
> clientPort=2181
> initLimit=5
> syncLimit=2
> server.0=10.150.27.61:2888:3888
> server.1=10.150.27.62:2888:3888
> server.2=10.150.27.63:2888:3888
> I wanted to add another node to the cluster. In fourth node's zoo.cfg, I created another entry for that node and started zk server. The zoo.cfg on the first 3 nodes was left unchanged. The fourth node was able to join the cluster even though the 3 nodes had no idea about the fourth node.
> zoo.cfg on fourth node:
> tickTime=2000
> dataDir=/var/zookeeper
> clientPort=2181
> initLimit=5
> syncLimit=2
> server.0=10.150.27.61:2888:3888
> server.1=10.150.27.62:2888:3888
> server.2=10.150.27.63:2888:3888
> server.3=10.17.117.71:2888:3888
> It looks like 10.17.117.71 is becoming an observer in this case. I was expecting that the leader will reject 10.17.117.71.
> # telnet 10.17.117.71 2181
> Trying 10.17.117.71...
> Connected to 10.17.117.71.
> Escape character is '^]'.
> stat
> Zookeeper version: 3.3.0--1, built on 04/02/2010 22:40 GMT
> Clients:
>  /10.17.117.71:37297[1](queued=0,recved=1,sent=0)
> Latency min/avg/max: 0/0/0
> Received: 3
> Sent: 2
> Outstanding: 0
> Zxid: 0x200000065
> Mode: follower
> Node count: 288

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