[jira] [Commented] (HBASE-13907) Document how to deploy a coprocessor

["Sean Busbey (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-13907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15061011#comment-15061011 ] 

Sean Busbey commented on HBASE-13907:
-------------------------------------

{code}
+[WARNING]
+.Use Coprocessors At Your Own Risk
+====
+Coprocessors are an advanced feature of HBase and are intended to be used by system
+developers only. Because coprocessor code runs directly on the RegionServer and has
+direct access to your data, they introduce the risk of data corruption, man-in-the-middle
+attacks, or other malicious data access. Currently, there is no mechanism to prevent
+data corruption by coprocessors, though work is underway on
+link:https://issues.apache.org/jira/browse/HBASE-4047[HBASE-4047].
+====
{code}

I'd include a note about how there's also no resource isolation, so a totally well intentioned but misbehaving coprocessor can severely degrade cluster performance and stability.

> Document how to deploy a coprocessor
> ------------------------------------
>
>                 Key: HBASE-13907
>                 URL: https://issues.apache.org/jira/browse/HBASE-13907
>             Project: HBase
>          Issue Type: Bug
>          Components: documentation
>            Reporter: Misty Stanley-Jones
>            Assignee: Misty Stanley-Jones
>         Attachments: HBASE-13907-1.patch, HBASE-13907-2.patch, HBASE-13907-v3.patch, HBASE-13907-v4.patch, HBASE-13907-v5.patch, HBASE-13907.patch
>
>
> Capture this information:
> > Where are the dependencies located for these classes? Is there a path on HDFS or local disk that dependencies need to be placed so that each RegionServer has access to them?
> It is suggested to bundle them as a single jar so that RS can load the whole jar and resolve dependencies. If you are not able to do that, you need place the dependencies in regionservers class path so that they are loaded during RS startup. Do either of these options work for you? Btw, you can load the coprocessors/filters into path specified by hbase.dynamic.jars.dir [1], so that they are loaded dynamically by regionservers when the class is accessed (or you can place them in the RS class path too, so that they are loaded during RS JVM startup).
> > How would one deploy these using an automated system? (puppet/chef/ansible/etc)
> You can probably use these tools to automate shipping the jars to above locations?
> > Tests our developers have done suggest that simply disabling a coprocessor, replacing the jar with a different version, and enabling the coprocessor again does not load the newest version. With that in mind how does one know which version is currently deployed and enabled without resorting to parsing `hbase shell` output or restarting hbase?
> Actually this is a design issue with current classloader. You can't reload a class in a JVM unless you delete all the current references to it. Since the current JVM (classloader) has reference to it, you can't overwrite it unless you kill the JVM, which is equivalent to restarting it. So you still have the older class loaded in place. For this to work, classloader design should be changed. If it works for you, you can rename the coprocessor class name and the new version of jar and RS loads it properly.
> > Where does logging go, and how does one access it? Does logging need to be configured in a certain way?
> Can you please specify which logging you are referring to?
> > Where is a good location to place configuration files?
> Same as above, are these hbase configs or something else? If hbase configs, are these gateway configs/server side? 



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)