<div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">Agreed, unique FQDNs on every instances is still a big issue for common workloads, hopefully solved by DNS services coming to OpenStack soon... I fully agree that the instance name and the FQDN of the instances should be 2 separate things, and even better, I think instances by default should try a reverse lookup first when they get on the network, and if available, collect a hostname, set it locally and display it in an additional column in the DB/tables/webUI, and allows OpenStack services clients to use either instance ID, name or hostname.</div>
<div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">What the OP is trying to do is also feasible by installing a bind service somewhere on the same subnet (bind9 minimum) and using the $GENERATE directive in your zone file, see here on how to write your zone file using that directive: <a href="http://www.oit.uci.edu/dcslib/bind/bind-9.2.1/Bv9ARM.ch06.html#AEN4097">http://www.oit.uci.edu/dcslib/bind/bind-9.2.1/Bv9ARM.ch06.html#AEN4097</a></div>
<div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default"><span style="font-family:georgia,serif">FWIW, AWS EC2 has a simple iterator that composes a unique hostname to any instance by parsing the public IP address, replacing '.' (dots) with '-' (to make it viable in a long hostname) and adding prefix/suffix to compose the hostname (compute zones and domain) with added dots for example: "</span><font face="georgia, serif"><a href="http://ec2-54-211-89-105.co">ec2-54-211-89-105.co</a></font><span style="font-family:georgia,serif"><a href="http://mpute-1.amazonaws.com">mpute-1.amazonaws.com</a>" is an instance with IP 54.211.89.105 ... it a simple and useful solution. You can check it yourself:</span></div>
<div class="gmail_default"><span style="font-family:georgia,serif"><br></span></div><div class="gmail_default"><div class="gmail_default"><font face="georgia, serif">$ host 54.211.89.105</font></div><div class="gmail_default">
<font face="georgia, serif">105.89.211.54.in-addr.arpa domain name pointer <a href="http://ec2-54-211-89-105.compute-1.amazonaws.com">ec2-54-211-89-105.compute-1.amazonaws.com</a>.</font></div></div><div class="gmail_default">
<br></div><div class="gmail_default"><font face="georgia, serif">Not having a unique FQDN on cloud instances can break many apps, and DNS services in IaaS should not be taken for granted (failure may happen), so IMHO, the best approach should be:</font></div>
<div class="gmail_default"><font face="georgia, serif">- boot instance, get on the network, do a reverse look up on IP to see if a DNS server answers with a FQDN , collect it and set it</font></div><div class="gmail_default">
<font face="georgia, serif">- if the look up fails, then resort to the iterator running and still end up with an unique hostname per instance.</font></div><div class="gmail_default"><font face="georgia, serif"><br></font></div>
<div class="gmail_default"><font face="georgia, serif">It seems a lot of public services hide this issue by allowing to launch only one instance at the time, but AFAIK, if you launch several instances at once using the nova CLI, you will end up with ALL instances having the same hostname (which is the instance name you have given to nova CLI) ... which breaks so many things it is not funny ... and is generally not a good idea or best practices either.</font></div>
<div class="gmail_default"><font face="georgia, serif"><br></font></div><div class="gmail_default"><font face="georgia, serif">If this functionality lands (very soon we hope), it will obviously also allows users to deal with hostnames directly rather than IP address, which in 2013, could give an archaic and old fashioned unfinished impression to users.</font></div>
<div class="gmail_default"><br></div><div class="gmail_default"><font face="georgia, serif">Cheers, sorry for the mini-rant but I would think this is one of the most urgent issues to address to see real automation and large scale apps.</font></div>
<div class="gmail_default"><br></div><div class="gmail_default"><font face="georgia, serif"><br></font></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Sun, Sep 15, 2013 at 12:39 PM, Tim Bell <span dir="ltr"><<a href="mailto:Tim.Bell@cern.ch" target="_blank">Tim.Bell@cern.ch</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
I don’t think there is a formal exit inside OpenStack to do this. You may have to make a small patch to Nova.<br>
<br>
It would be an interesting feature to define a plug-in architecture for this which would have several other uses.<br>
<div class="im HOEnZb"><br>
Tim<br>
<br>
> -----Original Message-----<br>
> From: Francesco Ceccarelli [mailto:<a href="mailto:ceccarel@fnal.gov">ceccarel@fnal.gov</a>]<br>
</div><div class="HOEnZb"><div class="h5">> Sent: 14 September 2013 20:40<br>
> To: Tim Bell<br>
> Cc: <a href="mailto:openstack@lists.openstack.org">openstack@lists.openstack.org</a><br>
> Subject: Re: [Openstack] openstack meta-data<br>
><br>
> Hello,<br>
> thanks for the help! I hadn't seen the command in the documentation, this can be helpful.<br>
> BTW my problem is to update metadata every time a machine is launched.<br>
> For example let's talk about the hostname. Every time I launch a machine, I would like to have well-configured metadata, with the<br>
> parameter public-hostname already set to a customized value. I don't want the instance name as public-hostname.<br>
><br>
> I hope I was clear and thanks again for the help, Francesco<br>
><br>
><br>
><br>
> On Sat, 2013-09-14 at 07:18 +0000, Tim Bell wrote:<br>
> > You can update the metadata associated with an instance using the 'nova meta' command. However, this only updates the metadata<br>
> (i.e.<br>
> > key value pairs) rather than the other attributes.<br>
> ><br>
> > Changing the server name would not alter the hostname of the VM, it would only alter the description in Nova.<br>
> ><br>
> > Can you explain a little more what you would like to be doing ?<br>
> ><br>
> > Tim<br>
> ><br>
> > > -----Original Message-----<br>
> > > From: Francesco Ceccarelli [mailto:<a href="mailto:ceccarel@fnal.gov">ceccarel@fnal.gov</a>]<br>
> > > Sent: 14 September 2013 00:11<br>
> > > To: <a href="mailto:openstack@lists.openstack.org">openstack@lists.openstack.org</a><br>
> > > Subject: [Openstack] openstack meta-data<br>
> > ><br>
> > > Is it possible to update instance meta-data, for example to set the public hostname?<br>
> > ><br>
> > > Thanks in advance,<br>
> > > Francesco<br>
> > ><br>
> > ><br>
> > > _______________________________________________<br>
> > > Mailing list: <a href="http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack" target="_blank">http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack</a><br>
> > > Post to : <a href="mailto:openstack@lists.openstack.org">openstack@lists.openstack.org</a><br>
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><br>
<br>
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