/srv/irclogs.ubuntu.com/2024/02/24/#ubuntu-server.txt

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deconexit18:35
deconHey all, I've just done a minor "apt upgrade" with 22.04 LTS on two servers. One of them worked perfectly, and on the other, I have this strange situation where if I type "netplan apply", I lose internet connectivity on one of the NICs, and then after about 2.5 minutes, connectivity is restored18:46
deconthe second NIC still works perfectly throughout, and I can access the server via the internal network on that NIC18:47
deconboth servers are pretty much identically configured, and this doesn't happen on the other server18:47
deconcan anyone think of a reason that "netplan apply" would suddenly break things, but only for 2.5 minutes please?18:47
deconit's a pretty simply dhcp setup on the NIC that loses connectivity18:48
deconI did a diff between the two netplan configs, and the only significant difference is the MAC addresses18:50
rfmdecon, no idea what causes the difference, but setting critical: true on the interface in netplan might paper over the problem18:53
deconrfm thanks, will try18:54
deconit's a production server, so every time i try something, i get painful downtime18:54
deconthe netplan docs say "special care will be taken by to not release the assigned IP"18:55
deconi guess that's a DHCP reference18:56
deconmaybe I should just hard-code the ip/gateway instead of using dhcp18:56
rfmusing static would at least tell if the problem is dhcp.  (I'd also look in syslog curing the apply)19:02
deconrfm ouch, downtime again when i changed to static IP and then did a "netplan try". /var/log/syslog doesn't contain anything relevant as far as I can see19:12
deconthis is so weird. both the servers were ordered at the same time, and I configured them both identically19:13
deconand critical: true doesn't help with19:17
deconeither*19:17
deconalthough I noticed downtime was closer to 1.5 mins instead of 2.5 mins when critial: true specified19:18
deconi wonder if it's due to me having disabled ipv619:29
fricklerdecon: you might want to use this to enable debug logging for systemd-networkd (assuming you didn't override the default backend) https://paste.opendev.org/show/byR0wW4fwpKqsbEvf0kF/19:29
deconfrickler ooh, thanks, will try19:31
deconfrickler lol this is so strange. i followed the instructions here https://superuser.com/a/1234599 to enable debugging as you mentioned, and now "netplan apply" gives no downtime. this is so confusing.19:38
kenyondecon: don't disable IPv621:21
znfneedrestart is probably the most obnoxious package that 22.04 shipped with 22:08
deconkenyon do you think that is what tripped it up?22:26
deconi think i will re-enable it, i just have to make sure i set up persistent ip6tables first22:27
deconit just occurred to me that one of the main differences between the server that had problems and the server that didn't, is that the server with the problems had more than one public IP address assigned to the NIC22:28
deconbut everything was working fine until I did a regular "apt upgrade" and then reboot22:29
kenyondecon: could be, because that's a config that likely doesn't get much testing, since it's bad practice22:55
kenyondecon: if there were multiple addresses, also make sure there weren't multiple default routes, assuming only one would be valid. that's a common misconfiguration that I see22:56
deconkenyon why might it be bad practice? The server has its own primary IP address for admin access only, but then also has secondary IPs for web sites hosted. This allows fail-over if the server goes down, because the switch can direct the traffic to a backup web server NIC instead23:16
patdk-lapI dunno why it would be bad, it's common usage to have many ips on the same nic23:19
patdk-lapif multible ips per nic is bad practice, then keepalived/pacemaker/ipvs are horrid creations23:21
patdk-laphave ips from the same subnet bound to many nics attached to the same subnet will cause a lot of pain though unless managed carefully23:22
deconpatdk-lap thanks, yeah i won't span them over multiple NICs.23:25

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