<div dir="ltr"><div class="gmail_default" style="font-size:small">I am running Kea on RockyLinux8 and RHEL8. For those systems I usually run "service kea-dhcp4 reload" and "service kea-dhcp6 reload" anytime I update the .json configuration files. And as far as I can tell, when I do that there are no DHCP replies from the server for 10-20 seconds. Or at least nothing is logged during that time. I have not looked at that very closely as reloading the Kea service is not very common for us now that it is all up and running.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">--Dan</div><div class="gmail_default" style="font-size:small"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Nov 18, 2022 at 2:24 AM Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch">Veronique.Lefebure@cern.ch</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div class="msg-8967846920327517071">
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Many thanks for these interesting hints!</div>
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A last question then: how do you notify KEA processes (kea-dhcp4, kea-dhcp6) in case you modify any of you json files ? with a "reload" command ?</div>
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Thanks,
<div>Veronique</div>
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<div id="m_-8967846920327517071divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Dan Oachs <<a href="mailto:doachs@gac.edu" target="_blank">doachs@gac.edu</a>><br>
<b>Sent:</b> Thursday, November 17, 2022 8:36 PM<br>
<b>To:</b> Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch" target="_blank">Veronique.Lefebure@cern.ch</a>><br>
<b>Cc:</b> <a href="mailto:kea-users@lists.isc.org" target="_blank">kea-users@lists.isc.org</a> <<a href="mailto:kea-users@lists.isc.org" target="_blank">kea-users@lists.isc.org</a>><br>
<b>Subject:</b> Re: [Kea-users] How to best update the KEA configuration on a HA hot-standby KEA setup</font>
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<div style="font-size:small">The great thing about Kea is that it is very flexible and you can make it work in a wide variety of ways and find the setup that works best for your situation.</div>
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<div style="font-size:small">In our case we have a hybrid setup. The kea-dhcp4.conf file has all the global settings, and we define the hosts-database for storing host reservations. We also break out all the subnet config into a separate
subnets.json file and have the main file include that.</div>
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<div style="font-size:small">We update the database directly from our own registration system, which is not recommended, but works fo us. We chose not to pay for the host commands hook library that is required to use the api example
you mentioned. <br>
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<div style="font-size:small">I am pretty sure that you can do almost everything in the database that you can do in the config file, but are only using the database to store the host information. I do see tables in the database that
start with dhcp4_client_class which would lead me to believe that you can do what you want with the database configuration.</div>
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<div style="font-size:small">--Dan</div>
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<div dir="ltr">On Thu, Nov 17, 2022 at 9:48 AM Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch" target="_blank">Veronique.Lefebure@cern.ch</a>> wrote:<br>
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Thanks Dan!</div>
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<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)">So you have a hybrid configuration ?</div>
<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)">What do you mean by "main configuration" ? <span style="margin:0px">Topology (shared-networks and subnets) in json file and host-reservations in a database ?</span></div>
<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)">Do you update the database using "reservation-add" (<a href="https://kea.readthedocs.io/en/latest/api.html?highlight=host%20reservation#reservation-add" title="https://kea.readthedocs.io/en/latest/api.html?highlight=host%20reservation#reservation-add" style="margin:0px" target="_blank">https://kea.readthedocs.io/en/latest/api.html?highlight=host%20reservation#reservation-add</a> )
?</div>
<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)"><br>
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<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)">We have client classes with a test expression that depends on the mac addresses of the clients.</div>
<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)">Can these classes be stored in the database as well ?</div>
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<div style="font-size:12pt;margin:0px;background-color:rgb(255,255,255)">Thanks,<br>
<span style="margin:0px">Veronique</span></div>
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<div id="m_-8967846920327517071x_m_-4452976748141530048divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Dan Oachs <<a href="mailto:doachs@gac.edu" target="_blank">doachs@gac.edu</a>><br>
<b>Sent:</b> Thursday, November 17, 2022 4:20 PM<br>
<b>To:</b> Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch" target="_blank">Veronique.Lefebure@cern.ch</a>><br>
<b>Cc:</b> <a href="mailto:kea-users@lists.isc.org" target="_blank">kea-users@lists.isc.org</a> <<a href="mailto:kea-users@lists.isc.org" target="_blank">kea-users@lists.isc.org</a>><br>
<b>Subject:</b> Re: [Kea-users] How to best update the KEA configuration on a HA hot-standby KEA setup</font>
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<div style="font-size:small">We also have all the main configuration in plain json files. Like you, we require hosts on some of our networks to be registered. Our registration system stores the MAC addresses in the Kea database. For the past year or so,
this has worked really well for us.</div>
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<div style="font-size:small">I would highly suggest looking into storing the MAC addresses in a database so you don't need to reload kea for every change. You don't need to use the database for anything else if you don't want to. This can also be done without
any of the extra hook libraries that cost money.<br>
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<div style="font-size:small">--Dan</div>
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<div dir="ltr">On Thu, Nov 17, 2022 at 2:19 AM Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch" target="_blank">Veronique.Lefebure@cern.ch</a>> wrote:<br>
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Hi,</div>
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We don't use any database for storing the KEA configuration: we use plain json configuration files<span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt">.</span></div>
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We need to update the configuration very regularly because we allow only known clients (pre-registered mac addresses), hence the list of host-reservations is quite volatile.</div>
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Véronique</div>
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<font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>From:</b> Dan Oachs <<a href="mailto:doachs@gac.edu" target="_blank">doachs@gac.edu</a>><br>
<b>Sent:</b> Wednesday, November 16, 2022 6:31 PM<br>
<b>To:</b> Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch" target="_blank">Veronique.Lefebure@cern.ch</a>><br>
<b>Cc:</b> <a href="mailto:kea-users@lists.isc.org" target="_blank">kea-users@lists.isc.org</a> <<a href="mailto:kea-users@lists.isc.org" target="_blank">kea-users@lists.isc.org</a>><br>
<b>Subject:</b> Re: [Kea-users] How to best update the KEA configuration on a HA hot-standby KEA setup</font>
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<div style="font-size:small">I am curious why you are updating the config every 5 minutes. We used to do that with our old DHCP server, but with Kea we moved to storing reservations in a database. That way we rarely need to make changes to the actual Kea
configuration that would necessitate a reload of the config.</div>
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<div style="font-size:small">--Dan</div>
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<div dir="ltr">On Wed, Nov 16, 2022 at 10:27 AM Veronique Lefebure <<a href="mailto:Veronique.Lefebure@cern.ch" target="_blank">Veronique.Lefebure@cern.ch</a>> wrote:<br>
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<span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt">Hi,</span><br>
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When running KEA on one single server, (no HA), and updating the KEA dhcp configuration file every 5 minute, using "config-set" </div>
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<a href="https://kea.readthedocs.io/en/latest/arm/ctrl-channel.html?highlight=config-set#the-config-set-command" title="https://kea.readthedocs.io/en/latest/arm/ctrl-channel.html?highlight=config-set#the-config-set-command" target="_blank">https://kea.readthedocs.io/en/latest/arm/ctrl-channel.html?highlight=config-set#the-config-set-command</a> ,</div>
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we can see that KEA does not reply to the DHCP requests during 30-35 seconds while "config-set" is running.</div>
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<span style="color:rgb(0,0,0);font-family:Calibri,Arial,Helvetica,sans-serif;font-size:12pt">Is it expected ?</span><br>
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If yes, if we add a second server in a HA hot-standby mode, can we expect it to answer to the DHCP requests while the first server is busy with config-set ?</div>
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If yes, we need to update the second server asynchronously with respect to the first one, else they would both be busy with "config-set" at the same time.</div>
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I would be interested to know how people are updating the KEA DHCP configuration in a HA hot-standby setup.</div>
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Thanks,
<div>Veronique</div>
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