On Mon, Sep 11, 2023, 10:54 Lennart Poettering <lennart@xxxxxxxxxxxxxx> wrote:
On So, 10.09.23 00:33, Nils Kattenbeck (nilskemail@xxxxxxxxx) wrote:
> Hello, I am currently trying to build a linux image with discoverable
> partitions in an A/B+etc+var scheme.
The discoverable partition scheme has no concept of /etc/ discovery. It
focusses on three basic setups:
1. writable root fs that contains /etc/, /var/ and /usr/ directly.
2. writable root fs that contains /etc/ and /var/ and gets an
immutable /usr/ mounted in
3. immutable root fs that contains /etc/ and /usr/ directly and gets a
writable /var/ mounted in. (the latter possibly as tmpfs, for truly
stateless systems)
There is also 4. with a writeable root which only contains /etc, an immutable /usr and a temporary /var. Though I guess that can be covered with the existing DPS...?
It was out assumption that these three cases should cover most
intended behaviours nicely, i.e. systems with modifiable config, code
and state. systems with modifiable config and state, but immutable
code. And finally systems with immutable config and code, but
modifiable state.
A system where /etc/ was separate from the root fs is not covered by
the above, because it is not clear what that would get us. if you want
it immutable, why not stick it on an immutable root fs. And if you
want it writable, why not stick it on a writable root fs directly?
My use case is basically 2, /etc has to be writeable to persist the machine-id across reboots, /var also has to be writeable and /usr can be immutable.
The problem I am then likely facing is that I create the partitions wrong. I am using mkosi and tried several different repart.d configuration with type=root+type=usr, type=root+type=var+type=use, and different CopyFiles= and Exclude(Target)Files= but none of them seemed to have worked.
Are there special requirements for what the respective partitions must or shall not contain when using several auto-discovered partitions? Or should I ask on the mkosi issue tracker?
Kind regards,
Nils
