[systemd-devel] Ensuring that a unit starts before any networking

[Zbigniew Jędrzejewski-Szmek]

On Sat, Jun 27, 2020 at 11:42:00AM +0100, Mark Rogers wrote:
> On Sat, 27 Jun 2020 at 11:06, Zbigniew Jędrzejewski-Szmek
> <zbyszek at in.waw.pl> wrote:
> > You should use Before=network-pre.target, Wants=network-pre.target.
> 
> Thanks, tried that but still not working:
> 
> $ journalctl -b | grep -Ei '(db2config|dhcpcd)'
> Feb 14 10:12:03 localhost systemd[1]: Starting dhcpcd on all interfaces...
> Feb 14 10:12:03 localhost dhcpcd[341]: read_config: fopen
> `/etc/dhcpcd.conf': No such file or directory
> [...]
> Jun 27 10:19:39 localhost dhcpcd[341]: wlan0: /etc/wpa_supplicant.conf
> does not exist
> [...]
> Jun 27 10:19:39 localhost dhcpcd[341]: read_config: fopen
> `/etc/dhcpcd.conf': No such file or directory
> [...]
> Jun 27 10:19:40 localhost dhcpcd[341]: eth0: soliciting an IPv6 router
> Jun 27 10:19:40 localhost dhcpcd[341]: eth0: soliciting a DHCP lease
> Jun 27 10:19:41 mypi db2config.py[325]: 2020-06-27 10:19:41 db2config
> Creating /tmp/sys//etc/dhcpcd.conf
> Jun 27 10:19:41 mypi db2config.py[325]: 2020-06-27 10:19:41 db2config
> Creating /tmp/sys//etc/wpa_supplicant/wpa_supplicant.conf
> 
> (Comments about that extract: the jump from Feb to Jun I assume is the
> clock getting updated from RTC, it's all from the same boot obviously;
> also note my db2config script doesn't run until after hostname is set
> which I would assume is set by the network startup?)
> 
> Unit file is currently:
> 
> [Unit]
> Description=Config generation from DB
> Before=network-pre.target
> Wants=network-pre.target
> 
> [Service]
> Type=oneshot
> ExecStart=/home/mark/bin/db2config.py
> 
> [Install]
> RequiredBy=network.target

And how does the unit that is running dhcpcd look like?

Zbyszek

> After any changes I'm using
> $ sudo systemctl daemon-reload
> $ sudo systemctl reenable db2config.service
> 
> ... although that's another area I'm not entirely clear about what
> exactly is required after a unit file change.
> 
> PS: Is list etiquette around here to CC on reply? Some love it, some
> hate it, others don't care...
reply-all is fine.

Zbyszek