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https://issues.apache.org/jira/browse/SLING-7830?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16580992#comment-16580992
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Dirk Rudolph commented on SLING-7830:
-------------------------------------

I agree on option 2 being more complex but for me this would be the favoured 
one. Lets say we want to run with our blue-green deployment a zero-downtime 
strategy where the majority of the users continue working on the green stack 
and a subset of samples working on the new blue stack for verification. Having 
the master in the blue stack could cause a service interruption for all users 
when an issue appears during verification. 

> Defined leader switch
> ---------------------
>
>                 Key: SLING-7830
>                 URL: https://issues.apache.org/jira/browse/SLING-7830
>             Project: Sling
>          Issue Type: Improvement
>          Components: Discovery
>            Reporter: Carsten Ziegeler
>            Priority: Major
>
> The current leader selection is based on startup time and sling id (mainly) 
> and is stable across changed in the topology for as long as the leader is up 
> and running.
> However there are use cases like blue green deployment where new instances 
> with a new version are started and taking over the functionality. However 
> with the current discovery setup, the leader would still be one of the 
> instances with the old version.
> With a new deployed version, tasks currently bound to the leader should run 
> on the new version.
> Therefore the leader needs to switch and stay the leader (until it dies).
> We probably need an additional criteria for the leader selection
> /cc [~egli]



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