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From Jian He <...@hortonworks.com>
Subject Re: [VOTE] Merge yarn-native-services branch into trunk
Date Tue, 05 Sep 2017 21:53:53 GMT
> 1) Did I miss it or is there no actual end-user documentation on how to use this? 

Yes, we are in the process of finishing up the the doc and posting it. We considered this
a release blocker for 3.0.0-beta1 and so working on it in parallel while the branch merge
happens.

> 	2) Lots of markdown problems in the NativeServicesDiscovery.md document.  This includes
things like ‘yarnsite.xml’ (missing a dash.)  Also, I’m also confused why it’s called
that when the title is YARN DNS, but whatever.


Thanks for pointing out. We will fix this.

>  Based on the documentation, this doesn’t appear to be a fully function DNS server
as an admin would expect (e.g., BIND, Knot, whatever).  Where’s forwarding? How do I setup
notify? Are secondaries even supported? etc, etc.

It seems like this is a rehash of some of the discussion you and others had on the JIRA. The
DNS here is a thin layer backed by service registry. My understanding from the JIRA is that
there are no claims that this is already a DNS with all the bells and whistles - its goal
is mainly to expose dynamic services running on YARN as end-points. Clearly, this is an optional
daemon, if the provided feature set is deemed insufficient, an alternative solution can be
plugged in by specific admins because the DNS piece is completely decoupled from the rest
of native-services. 

> In fact:  was this even tested on port 53? How does this get launched such that it even
has access to open port 53?  I don’t see any calls to use the secure daemon code in the
shell scripts. Is there any jsvc voodoo or is it just “run X as root”?

Yes, we have tested this DNS server on port 53 on a cluster by running the DNS server as root
user. The port is clearly configurable, so the admin has two options. Run as root + port 53.
Run as non-root + non-privileged port. We tested and left it as port 53 to keep it on a standard
DNS port. It is already documented as such though I can see that part can be improved a little.

> 	4) Post-merge, yarn usage information is broken.  This is especially bad since it doesn’t
appear that YarnCommands was ever updated to include the new sub-commands.

The “yarn” usage command is working for me. what do you mean ? 
Yeah, looks like some previous features also forgot to update YarnCommands.md for the new
sub commands 


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