morgan/systemd
1
0
Fork 0
mirror of https://github.com/morgan9e/systemd synced 2026-04-14 00:14:32 +09:00
Code Issues Packages Projects Releases Wiki Activity

Use paths specified from environment variables for /etc configuration files

Browse Source 
Some configuration files that need updates are directly under in /etc. To
update them atomically, we need write access to /etc. For Ubuntu Core this is
an issue as /etc is not writable. Only a selection of subdirectories can be
writable. The general solution is symlinks or bind mounts to writable places.
But for atomic writes in /etc, that does not work. So Ubuntu has had a patch
for that that did not age well.

Instead we would like to introduce some environment variables for alternate
paths.

 * SYSTEMD_ETC_HOSTNAME: /etc/hostname
 * SYSTEMD_ETC_MACHINE_INFO: /etc/machine-info
 * SYSTEMD_ETC_LOCALTIME: /etc/localtime
 * SYSTEMD_ETC_LOCALE_CONF: /etc/locale.conf
 * SYSTEMD_ETC_VCONSOLE_CONF: /etc/vconsole.conf
 * SYSTEMD_ETC_ADJTIME: /etc/adjtime

While it is for now expected that there is a symlink from the standard, we
still try to read them from that alternate path. This is important for
`/etc/localtime`, which is a symlink, so we cannot have an indirect symlink or
bind mount for it.

Since machine-id is typically written only once and not updated. This commit
does not cover it. An initrd can properly create it and bind mount it.
This commit is contained in:
Valentin David
2025-03-10 10:53:41 +01:00
committed by Lennart Poettering
parent fa34fda2eb
commit 0dc39dffbd
19 changed files with 376 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
docs/ENVIRONMENT.md
View File

@@ -294,6 +294,9 @@ All tools:
first existing unit listed in the environment variable, and
`timedatectl set-ntp off` disables and stops all listed units.
* `$SYSTEMD_ETC_ADJTIME` - override the path to the hardware clock settings
file. The default is `/etc/adjtime`.
`systemd-sulogin-shell`:
* `$SYSTEMD_SULOGIN_FORCE=1` — This skips asking for the root password if the
@@ -787,3 +790,25 @@ Tools using the Varlink protocol (such as `varlinkctl`) or sd-bus (such as
`systemd.factory_reset=` kernel command line option: if set to false,
requesting a TPM clearing is skipped, and the command immediately exits
successfully.
`systemd-timedated`, `systemd-firstboot`, `systemd`:
* `$SYSTEMD_ETC_LOCALTIME` - override the path to the timezone symlink. The
default is `/etc/localtime`. The directory of the path should exist and not
be removed.
`systemd-hostnamed`, `systemd-firstboot`:
* `$SYSTEMD_ETC_HOSTNAME` - override the path to local system name
configuration file. The default is `/etc/hostname`.
* `$SYSTEMD_ETC_MACHINE_INFO` - override the path to the machine metadata file. The
default is `/etc/machine-info`.
`systemd-localed`, `systemd-firstboot`:
* `$SYSTEMD_ETC_LOCALE_CONF` - override the path to the system-wide locale
configuration file. The default is `/etc/locale.conf`.
* `$SYSTEMD_ETC_VCONSOLE_CONF` - override the path to the virtual console
configuration file. The default is `/etc/vconsole.conf`.