<html><head><base href="x-msg://986/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi<div><br><div><div>On 2 Apr 2013, at 20:29, Kapil Goyal wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div bgcolor="white" lang="EN-US" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">I noticed that names of log files, DB etc. are created from node-name. Node-name itself is created based on hostname by default. So, if hostname changes, node-names changes and so do the DB, logs etc.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "></span></div></div></div></span></blockquote><div><br></div><div>I can see why this is a source of difficulty if your hostname changes with regularly, but surely the better solution would be to find some way to prevent the hostname from changing?</div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div bgcolor="white" lang="EN-US" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><o:p> </o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">My idea was to fix the node-name and make it independent of the hostname, thus fixing the names of DB and logs. But, if I try to use a clustered or federated setup, the multiple RabbitMQ instances will need to talk to each other and I cannot use the same fixed node-name for all the instances. To solve that, I thought I will generate the node-name at first boot of the RabbitMQ server (and not change it ever). Random-string was just to ensure that all RabbitMQ instances get unique node-names.<o:p></o:p></span></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "></span></div></div></div></span></blockquote><div><br></div><div>I understand that, but it will not work. The node name has to be a valid Erlang node name, and that has the form <name>@<host> where the <host> part can be either a fully qualified domain name or a short name such as 'myhost'. You cannot use 'rabbit@987sdfkjhisd7f7d87sdf' to connect to other Erlang nodes unless the part after the @ is actually the hostname. In addition to this, mnesia - Erlang's distributed database - insists on creating its on-disk schema in a folder which is named Mnesia.<node-name>, and we have no control over that. Renaming the mnesia directory is fine in principle, although if you change the node's name when you're in a cluster then there's a bigger problem because you'll have to notify all the other member nodes that you're changing name - I think the only way to do that would be to leave the cluster and then come back as another node. </div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div bgcolor="white" lang="EN-US" link="blue" vlink="purple"><div class="WordSection1" style="page: WordSection1; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "><o:p> </o:p></span></div><div><div style="border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; border-top-style: solid; border-top-color: rgb(181, 196, 223); border-top-width: 1pt; padding-top: 3pt; padding-right: 0in; padding-bottom: 0in; padding-left: 0in; position: static; z-index: auto; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; ">From:</span></b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; "><span class="Apple-converted-space"> </span><a href="mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com">rabbitmq-discuss-bounces@lists.rabbitmq.com</a> [mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com]<span class="Apple-converted-space"> </span><b>On Behalf Of<span class="Apple-converted-space"> </span></b>Tim Watson<br><b>Sent:</b><span class="Apple-converted-space"> </span>Tuesday, April 02, 2013 11:59 AM<br><b>To:</b><span class="Apple-converted-space"> </span>Discussions about RabbitMQ<br><b>Cc:</b><span class="Apple-converted-space"> </span>Discussions about RabbitMQ<br><b>Subject:</b><span class="Apple-converted-space"> </span>Re: [rabbitmq-discuss] Configuring RabbitMQ to support change in hostname<o:p></o:p></span></div></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><o:p> </o:p></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">Hi<o:p></o:p></div></div><div><p class="MsoNormal" style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 12pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><br>On 2 Apr 2013, at 19:44, Kapil Goyal <<a href="mailto:goyalk@vmware.com" style="color: blue; text-decoration: underline; ">goyalk@vmware.com</a>> wrote:<o:p></o:p></p></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt; "><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); ">So, RabbitMQ does not really support change in hostname at all without losing existing data. Is that correct?</span><o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> </span><o:p></o:p></div></div></blockquote><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><o:p> </o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">Erm not quite - if you copy/rename the mnesia directory you can work around this. The node name is dev1 then you can rename/move directories to something else (or override directory names to use something that isn't bound to the node name if you prefer). I don't see how your proposed use of a<o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">Random stein would make any different though. <o:p></o:p></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><br><br><o:p></o:p></div><div><div><div style="border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; border-top-style: solid; border-top-color: rgb(181, 196, 223); border-top-width: 1pt; padding-top: 3pt; padding-right: 0in; padding-bottom: 0in; padding-left: 0in; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; ">From:</span></b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; "><span class="Apple-converted-space"> </span><a href="mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">rabbitmq-discuss-bounces@lists.rabbitmq.com</a><span class="Apple-converted-space"> </span>[<a href="mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com</a>]<span class="Apple-converted-space"> </span><b>On Behalf Of<span class="Apple-converted-space"> </span></b>Tim Watson<br><b>Sent:</b><span class="Apple-converted-space"> </span>Tuesday, April 02, 2013 4:31 AM<br><b>To:</b><span class="Apple-converted-space"> </span>Discussions about RabbitMQ<br><b>Cc:</b><span class="Apple-converted-space"> </span>Discussions about RabbitMQ<br><b>Subject:</b><span class="Apple-converted-space"> </span>Re: [rabbitmq-discuss] Configuring RabbitMQ to support change in hostname</span><o:p></o:p></div></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span class="apple-style-span">On 29 Mar 2013, at 23:18, Kapil Goyal <<a href="mailto:goyalk@vmware.com" style="color: blue; text-decoration: underline; ">goyalk@vmware.com</a>> wrote:</span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt; "><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> am thinking of solving it by replacing rabbit@localhost with rabbit@<random string> before RabbitMQ starts for the first time. Does <random string> have to be DNS resolvable?</span><o:p></o:p></div></div></blockquote><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">Yes. It needs to be the proper hostname for the node.<o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><br><br><br><o:p></o:p></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> </span><o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; color: rgb(31, 73, 125); "> </span><o:p></o:p></div><div><div style="border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; border-top-style: solid; border-top-color: rgb(181, 196, 223); border-top-width: 1pt; padding-top: 3pt; padding-right: 0in; padding-bottom: 0in; padding-left: 0in; "><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; ">From:</span></b><span style="font-size: 10pt; font-family: Tahoma, sans-serif; "><span class="Apple-converted-space"> </span><a href="mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">rabbitmq-discuss-bounces@lists.rabbitmq.com</a><span class="Apple-converted-space"> </span>[<a href="mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">mailto:rabbitmq-discuss-bounces@lists.rabbitmq.com</a>]<span class="Apple-converted-space"> </span><b>On Behalf Of<span class="Apple-converted-space"> </span></b>Dushin Fred<br><b>Sent:</b><span class="Apple-converted-space"> </span>Thursday, March 28, 2013 6:44 PM<br><b>To:</b><span class="Apple-converted-space"> </span>Discussions about RabbitMQ<br><b>Subject:</b><span class="Apple-converted-space"> </span>Re: [rabbitmq-discuss] Configuring RabbitMQ to support change in hostname</span><o:p></o:p></div></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">See<o:p></o:p></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><a href="http://lists.rabbitmq.com/pipermail/rabbitmq-discuss/2013-February/025368.html" style="color: blue; text-decoration: underline; ">http://lists.rabbitmq.com/pipermail/rabbitmq-discuss/2013-February/025368.html</a><o:p></o:p></div><div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div><div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">On Mar 28, 2013, at 4:53 PM, Kapil Goyal <<a href="mailto:goyalk@vmware.com" style="color: blue; text-decoration: underline; ">goyalk@vmware.com</a>> wrote:<o:p></o:p></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><br><br><br><br><o:p></o:p></div><div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">RabbitMQ creates a new database if hostname is changed (as documented at<span class="apple-converted-space"> </span><a href="http://www.rabbitmq.com/ec2.html" style="color: blue; text-decoration: underline; "><span style="color: purple; ">http://www.rabbitmq.com/ec2.html</span></a>).</span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; "> </span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">I need to support the hostname change on my RabbitMQ server without impacting its functioning. Can I accomplish this by setting the NODENAME environment variable in rabbitmq-env.conf. It seems from rabbitmq-server script that names of database, logs etc. try to use this variable before resorting to using hostname. Is this the right approach? Are there any side-effects to look out for?</span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; "> </span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Thanks</span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Kapil Goyal</span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">Sr. MTS</span><o:p></o:p></div></div><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 11pt; font-family: Calibri, sans-serif; ">VMware Inc.</span><o:p></o:p></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "><span style="font-size: 13.5pt; font-family: Verdana, sans-serif; ">_______________________________________________<br>rabbitmq-discuss mailing list<br><a href="mailto:rabbitmq-discuss@lists.rabbitmq.com" style="color: blue; text-decoration: underline; "><span style="color: purple; ">rabbitmq-discuss@lists.rabbitmq.com</span></a><br><a href="https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss" style="color: blue; text-decoration: underline; "><span style="color: purple; ">https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss</span></a></span><o:p></o:p></div></div></div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; "> <o:p></o:p></div></div></div></div></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt; "><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">_______________________________________________<br>rabbitmq-discuss mailing list<br><a href="mailto:rabbitmq-discuss@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">rabbitmq-discuss@lists.rabbitmq.com</a><br><a href="https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss" style="color: blue; text-decoration: underline; ">https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss</a><o:p></o:p></div></div></blockquote></div><blockquote style="margin-top: 5pt; margin-bottom: 5pt; "><div><div style="margin-top: 0in; margin-right: 0in; margin-left: 0in; margin-bottom: 0.0001pt; font-size: 12pt; font-family: 'Times New Roman', serif; ">_______________________________________________<br>rabbitmq-discuss mailing list<br><a href="mailto:rabbitmq-discuss@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">rabbitmq-discuss@lists.rabbitmq.com</a><br><a href="https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss" style="color: blue; text-decoration: underline; ">https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss</a><o:p></o:p></div></div></blockquote></div>_______________________________________________<br>rabbitmq-discuss mailing list<br><a href="mailto:rabbitmq-discuss@lists.rabbitmq.com" style="color: blue; text-decoration: underline; ">rabbitmq-discuss@lists.rabbitmq.com</a><br><a href="https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss" style="color: blue; text-decoration: underline; ">https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq-discuss</a></div></span></blockquote></div><br></div></body></html>