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https://issues.apache.org/jira/browse/CASSANDRA-1654?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12925478#action_12925478
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Jon Hermes edited comment on CASSANDRA-1654 at 10/27/10 2:01 PM:
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Current working strategy is to poke 
169.254.169.254(zeroconf)/x/x/availability-zone, which will respond with the 
information I need ("us-east-1a", etc.).
During node bootup, if DD sees EC2Snitch as the endpoint_snitch, it will 
populate the region/zone off that information, and staticly return that when 
needed to the EC2Snitch.

The usage is commented, "Don't use EC2Snitch if you're not on EC2", as that url 
will most likely 404, but I'm not sure what else I can do to prevent/safeguard 
it's usage. Should I be letting the GET fail? Defaulting region/zone to "" (all 
nodes are in the same region/zone)? This is during boot-time, so it's highly 
visible in any event.

      was (Author: jhermes):
    Current working strategy is to poke 169.254.169.154/x/x/availability-zone, 
which will respond with the information I need ("us-east-1a", etc.).
During node bootup, if DD sees EC2Snitch as the endpoint_snitch, it will 
populate the region/zone off that information, and staticly return that when 
needed to the EC2Snitch.

The usage is commented, "Don't use EC2Snitch if you're not on EC2", as that url 
will most likely 404, but I'm not sure what else I can do to prevent/safeguard 
it's usage. Should I be letting the GET fail? Defaulting region/zone to "" (all 
nodes are in the same region/zone)? This is during boot-time, so it's highly 
visible in any event.
  
> EC2Snitch
> ---------
>
>                 Key: CASSANDRA-1654
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-1654
>             Project: Cassandra
>          Issue Type: New Feature
>          Components: Core
>            Reporter: Jonathan Ellis
>            Assignee: Jon Hermes
>             Fix For: 0.7.1
>
>
> This will be a snitch extending AbstractNetworkTopologySnitch that pulls DC 
> from instance metadata placement_availability_zone.
> I don't think we can get rack information so the choice is between picking 
> something unique-per-machine to be the rack or assigning everything in the DC 
> the same rack.  Second seems easier, so let's use placement_availability_zone 
> for rack, too.

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