<div dir="ltr"><div>The intra service unit coordination for a round robin activity is best served by a peer relation. The signalling of the patch application/change needs to be done externally via the client api atm, ie. changing the service configuration to denote a vcs revision or patch file. <br>
<br>A subordinate isn't needed. Subordinates are helpful for generic or ancillary
features, but structuring core functionality of another service there tends to obfuscate the charm and the usage imo.<br><br></div>cheers,<br>Kapil<br></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, May 21, 2013 at 9:26 AM, Denis Weerasiri <span dir="ltr"><<a href="mailto:ddweerasiri@gmail.com" target="_blank">ddweerasiri@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi,<div>I am trying to realize the following patch installation scenario in a application cluster fronted with a load-balancer.</div>
<div>Let's assume I use Puppet like a configuration management tool to install the patch in each node.</div>
<div><br></div><div>Here is the scenario</div><div><ul><li>The cluster is consist of two nodes named A and B.</li><li>First stop the node A and install the patch using a puppet manifest and restart the node A</li><li>Then stop the node B and install the patch using a puppet manifest and restart the node B</li>
<li>So the application is available 100% at all the times</li></ul><div>The problem is, how can I write a charm to automate this patch installation scenario, where <i>Juju should be able to propagate life-cycle changes in one service unit in Node A to the other service unit in Node B</i>. </div>
</div><div>When I went through the Juju doc, I found about subordinate services which may solve my problem <a href="https://juju.ubuntu.com/docs/subordinate-services.html" target="_blank">https://juju.ubuntu.com/docs/subordinate-services.html</a> . Is this the correct way of automating this patch installation scenario?</div>
<div>Or how is it possible to propagate life-cycle changes in one service unit to the another service unit?</div><span class="HOEnZb"><font color="#888888"><div><br></div><div><br></div><div><div><br></div>-- <br>Thanks,<br>
Denis<br>----------------------------------------------------------<br>
<div><b>Denis Weerasiri</b></div><div><font size="1"><b><br></b></font></div><div><a href="http://wso2.com/" target="_blank"></a><i></i><a href="http://wso2.com/" target="_blank"><i></i></a><i><font size="1">sit</font><span style="font-size:x-small">e: </span></i><a href="https://sites.google.com/site/ddweerasiri/" target="_blank"><i><span style="font-size:x-small">https://sites.google.com/site/ddweerasiri/</span></i></a></div>
<div><i><span style="font-size:x-small">blog: </span></i><a href="http://ddweerasiri.blogspot.com/" target="_blank"><i><span style="font-size:x-small">http://ddweerasiri.blogspot.com</span></i></a><i><span style="font-size:x-small"><br>
twitter: </span></i><a href="http://twitter.com/ddweerasiri" target="_blank"><i><span style="font-size:x-small">http://twitter.com/ddweerasiri</span></i></a><i><span style="font-size:x-small"><br>linked-in: </span></i><a href="http://lk.linkedin.com/in/ddweerasiri" target="_blank"><i><span style="font-size:x-small">http://lk.linkedin.com/in/ddweerasiri</span></i></a></div>
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<br></blockquote></div><br></div>