jump to navigation

NetworkManager, systemd-networkd and slow boots September 29, 2017

Posted by jdstrand in ubuntu.
add a comment

This may be totally obvious to many but I thought I would point out a problem I had with slow boot and how I solved it to highlight a neat feature of systemd to investigate the problem.

I noticed that I was having terrible boot times, so I used the `systemd-analyze critical-chain` command to see what the problem was. This showed me that `network-online.target` was taking 2 minutes. Looking at the logs (and confirming with `systemd-analyze blame`), I found it was timing out because `systemd-networkd` failed to bring interfaces either online or to fail (I was in an area where I had not connected to the existing wifi before and the wireless interface was scanning instead of failing). I looked around and found that I had no configuration for systemd-networkd (/etc/systemd/network was empty) or for netplan (/etc/netplan was empty), so I simply ran `sudo systemctl disable systemd-networkd` (leaving NetworkManager enabled) and I then had a very fast boot.

I need to file a bug on the cause of the problem, but I found the `systemd-analyze` command so helpful, I wanted to share. :)

UPDATE: this bug was reported as https://launchpad.net/bugs/1714301 and fixed in systemd 234-2ubuntu11.

Easy ssh into libvirt VMs and LXD containers September 20, 2017

Posted by jdstrand in canonical, ubuntu, ubuntu-server.

Finding your VMs and containers via DNS resolution so you can ssh into them can be tricky. I was talking with St├ęphane Graber today about this and he reminded me of his excellent article: Easily ssh to your containers and VMs on Ubuntu 12.04.

These days, libvirt has the `virsh dominfo` command and LXD has a slightly different way of finding the IP address.

Here is an updated `~/.ssh/config` that I’m now using (thank you St├ęphane for the update for LXD):

Host *.lxd
    #User ubuntu
    #StrictHostKeyChecking no
    #UserKnownHostsFile /dev/null
    ProxyCommand nc $(lxc list -c s4 $(echo %h | sed "s/\.lxd//g") %h | grep RUNNING | cut -d' ' -f4) %p
Host *.vm
    #StrictHostKeyChecking no
    #UserKnownHostsFile /dev/null
    ProxyCommand nc $(virsh domifaddr $(echo %h | sed "s/\.vm//g") | awk -F'[ /]+' '{if (NR>2 && $5) print $5}') %p

You may want to uncomment `StrictHostKeyChecking` and `UserKnownHostsFile` depending on your environment (see `man ssh_config`) for details.

With the above, I can ssh in with:

$ ssh foo.vm uptime
16:37:26 up 50 min, 0 users, load average: 0.00, 0.00, 0.00
$ ssh bar.lxd uptime
21:37:35 up 12:39, 2 users, load average: 0.55, 0.73, 0.66