Hi all,
We recently migrated a busy Koha instance from an on-premises server to an Azure cloud server. During that move, we also took the opportunity to switch to using Elasticsearch (not located on the same virtual machine). Over time, we noticed that we were getting issues with SIP2 connections and with Koha's Elasticsearch indexer worker timing out. Especially during the least busy parts of the day. After some investigation, we learned that Azure allows TCP connections to only be idle for a maximum of 4 minutes (https://learn.microsoft.com/en-us/azure/firewall/long-running-sessions). One solution is to implement application-level keepalives, but that wasn't practical with Koha's Elasticsearch client library or the SIP2 server. Instead, I opted to utilize Linux's TCP keepalive implementation, which operates at a lower level of the technology stack. Fortunately, Koha's Elasticsearch client library is already compatible with TCP keepalives, so I just needed to tweak the "net.ipv4.tcp_keepalive_time" kernel parameter via "sysctl". I dropped the keepalive to under the 4 minute threshold (from the default of 2 hours), and now no more timeouts with Koha's Elasticsearch indexer worker! Unfortunately, Koha's SIP2 server doesn't support the TCP keepalives out of the box. However, I've written a patch at "Bug 37087 - Add support for TCP keepalive to SIP server" which adds granular TCP keepalive support which can actually be configured via the SIPconfig.xml configuration file (without needing to change any kernel parameters at all). I've written up a bit about it on the wiki: https://wiki.koha-community.org/wiki/Koha_SIP2_server_setup#Microsoft_Azure_ cloud_platform https://wiki.koha-community.org/wiki/Elasticsearch#Microsoft_Azure_cloud_pla tform I hope that this information is useful to other people out in the world implementing Koha. It was a very annoying problem with a surprisingly simple solution in the end. David Cook Senior Software Engineer Prosentient Systems Suite 7.03 6a Glen St Milsons Point NSW 2061 Australia Office: 02 9212 0899 Online: 02 8005 0595 _______________________________________________ Koha mailing list http://koha-community.org Koha@lists.katipo.co.nz Unsubscribe: https://lists.katipo.co.nz/mailman/listinfo/koha
