New Phoenix project, why do we need `DNSCluster`?

As per title, I found this in my supervision tree after generating a Phoenix 1.7 project:

{DNSCluster, query: Application.get_env(:my_app, :dns_cluster_query) || :ignore},

The description on hexdocs – “Simple DNS based cluster discovery.” – does not tell me anything that explains why does a Phoenix project needs it.

Does anybody know?

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It’s there to set people up with dns based clustering out of the box, which is a common way of connecting nodes, like on, but also for things like kubernetes afaik. When disabled is simply does nothing. You can remove it if you don’t need it.


Yep I’ve noticed that the :ignore parameter to it simply prevents it from starting but I still don’t want the dns_cluster in my dependencies.

Thanks, I am removing it then.

There is this video where @chrismccord talks about dns_cluster…

…in the distributed Elixir chapter

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