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From "ASF subversion and git services (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QPID-6035) HA clearly distinguish qpid-ha commands intended for cluster manager.
Date Fri, 22 Aug 2014 18:08:11 GMT

    [ https://issues.apache.org/jira/browse/QPID-6035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14107210#comment-14107210
] 

ASF subversion and git services commented on QPID-6035:
-------------------------------------------------------

Commit 1619877 from [~aconway] in branch 'qpid/trunk'
[ https://svn.apache.org/r1619877 ]

QPID-6035: HA clearly distinguish qpid-ha commands intended for cluster manager.

This commit adds a --cluster-manager flag to qpid-ha tool.

Without this flag
- the 'promote' command is not listed in the tool help.
- using the promote command raises an error saying that it is only for cluster manager use
  and mentioning the --cluster-manager flag.

With the flag: promote functions as before.

The qpid-ha help text for promote is also more clear now that it is for cluster
manager only.

Originally the idea was to split qpid-ha into two tools but I have kept one tool
with the flag and warning messages because it:

- avoids packaging changes that might trip things up.

- helps people who are already using qpid-ha promote: their scripts will
  break but the error message explains how to fix it.

I think the special role of promote is sufficiently clear now even if it is
part of the same tool.

This commit also updates the following to take account of the new flag:
- rgmanager qpidd-primary script.
- qpidd tests.
- qpid book HA chapter.

NOTE: THIS WILL BREAK TEST HARNESSES that do promotion outside of rgmanager.
You'll need to add the --cluster-manager flag in the relevant places.

> HA clearly distinguish qpid-ha commands intended for cluster manager.
> ---------------------------------------------------------------------
>
>                 Key: QPID-6035
>                 URL: https://issues.apache.org/jira/browse/QPID-6035
>             Project: Qpid
>          Issue Type: Improvement
>          Components: C++ Clustering
>    Affects Versions: 0.30
>            Reporter: Alan Conway
>            Assignee: Alan Conway
>             Fix For: 0.31
>
>
> The qpid-ha tool has two roles. It provides many commands for system administrators to
monitor a cluster. It also provides the 'promote' command that should only be used by a cluster
manager.
> Qpid relies on an external cluster manager (usually rgmanager) to start and stop brokers
and to ensure that only one  broker is ever primary. This only works if rgmanager is the only
agent that uses "qpid-ha promote". Otherwise we can end up with multiple primaries and cluster
malfunction.
> The difference between qpid-ha commands for system administrators vs. for cluster managers
is not sufficiently clear. A sysadmin could make the mistake of thinking it is Ok to promote
a broker without going through rgmanager. This needs to be more clear to avoid accidents.



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