[systemd-devel] Using timedatectl on a readonly rootfile system using mender

[Lennart Poettering]

On Fr, 04.09.20 15:54, Shravan Singh (shravan at bluesparq.com) wrote:

> Yes, But help me understand.
> I think you said that you are not convinced as to why that has to done.
>
> My argument is very simple shouldn't a Linux environment allow change in
> timezone easily?

Oh we do. But if your want configuration to be changable, then mount
/etc writable.

You have two contradicting goals: you want immutable config, but then
you want to change config. So how's that gonna work?

If you want your persistent config changable then make it changable,
i.e. mount /etc/ writable.

> Now I am not an expert in Linux kernel development. But I see that some of
> the files, even though they reside in /etc  are linked to file in /run
> Like *resolv.conf.  *Which allows dynamic changes.

I explained this already. DNS server data today is much less config
than state, acquired dynamically via DHCP, hence most distros don#t
configure it in /etc so much anymore, but manage it in /run (where
transient state is generally kept), and only keep a compat symlink in
/etc. If you try to convince people though that the local timezone
should just be transient state and not persistent config you'll have a
hard time. I for one am certainly not convinced that the timezones are
state...

I mean, the line between persistent configuration and transient state
is blurry, but in the case of DNS settings and timezone settings I
certainly can draw a line easily.

> timezone activity change is a very basic change one that needs to be
> supported by the system. Why guard it with so much.

We don't do that. Just make /etc/ writable ffs, if you want stuff in
/etc to be changable.

Lennart

--
Lennart Poettering, Berlin