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<p class="MsoNormal"><span style="font-size:11.0pt">I’m working on a project to perform A/B testing with the web hosting platform. The simple version is that we are hosted everything on Azure and want to compare using their Web Apps versus running a VM with
IIS.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">My question is about load balancing since there seems to be two ways to go about this. First is to use a simple config where I setup the three hosts I’m testing like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">upstream ym-host<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> least_conn;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> server ysm-iis-prod1.northcentralus.cloudapp.azure.com;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> server ysm-iis-prod2.northcentralus.cloudapp.azure.com;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> server ysm-ym-live-prod.trafficmanager.net;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">This works but I am not sure how to set a header to indicate which host is being used.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The alternative is to use split_client and the same configuration looks like this:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">upstream ym_host1<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> server ysm-iis-prod1.northcentralus.cloudapp.azure.com;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">upstream ym_host2<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> server ysm-iis-prod2.northcentralus.cloudapp.azure.com;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">upstream ym_host3<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> server ysm-ym-live-prod.trafficmanager.net;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">split_clients "$arg_token" $ymhost<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">{<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> 25% ym_host1;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> 25% ym_host2;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"> 50% ym_host3;<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">}<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">Granted the $arg_token will change to something else but for now I use that since I can manipulate it easier.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The benefit of the second is that I can add a header like X-UpstreamHost $ymhost and then I can see which host I am hitting.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">The benefit of the first is using the least connected round robin approach but I can’t add a header to indicate which host is being hit. For good reasons I won’t get into, adding the header at the web app
is not an option. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">My question is three part<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">Which is considered the best approach to load balance for this sort of testing?
<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">Is there a way to get the name of the host being used if I stick with the simpler approach that uses just the single upstream configuration?
<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">What would be the best variable to use for the split_client approach to achieve closest to a round robin?
<o:p></o:p></span></li></ol>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A">___________________________________________<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A">Michael Friscia<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A">Office of Communications<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A">Yale School of Medicine<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A">(203) 737-7932 - office<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A">(203) 931-5381 - mobile<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;color:#44546A"><a href="http://web.yale.edu/"><span style="color:#44546A">http://web.yale.edu</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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