Bug#931130: Document that local configuration for dummy and bonding modules are getting overwritten by systemd
Michael Biebl wrote:
> Am 29.06.19 um 15:09 schrieb Justin B Rye:
>> + configure a machine as a router, may encounter problems upgrading to buster.
>> + New versions of <systemitem role="package">udev</systemitem> install a
>
> That modprobe config file is shipped by the systemd package, not by udev.
Ah, thanks.
>> A file in
>> + <filename>/lib/modprobe.d</filename> can be overridden by one with the
>> + same name under <filename>/etc/modprobe.d</filename>, but the names are
>> + processed in alphabetical order, so
>
> That sentence is a bit confusing: files with the same name are
> overridden. period. there is no but.
If there wasn't a "but", people wouldn't have been caught out! It's
true that if you create a file in /etc then you don't need to worry
about the one it masks in /lib, but you do still need to worry about
others that might turn up in /lib with names that sort later.
> Are you trying to say that files can be overridden as a whole but
> usually its better to only override specific settings in a local
> configuration file which doesn not have the same name?
No, I *could* have added a paragraph explaining the drawbacks of using
the filename /etc/modprobe.d/systemd.conf, but it seemed simpler just
to not mention the suboptimal solution. After all, who knows what
might turn up in bullseye's /etc/modprobe.d/udev.conf?
> (which is indeed a useful recommendation because future updates of
> systemd.conf might be missed if you name the file
> /etc/modprobe.d/systemd.conf).
The simplest way of looking at this bug is that the old approach
(as recommended in legacy HOWTOs) of using filenames like
"/etc/modprobe.d/dummy.conf" needs to be updated to using something
like "/etc/modprobe.d/zz-local.conf". My explanation covers things in
what I hoped was just enough detail to make it clear why that change
is needed.
I've stared at it quite a bit and can't find a clearer way of saying
it. Here's a patch with just the s/udev/systemd/ change; I'll go for
a walk and then try looking at it again.
--
JBR with qualifications in linguistics, experience as a Debian
sysadmin, and probably no clue about this particular package
diff --git a/en/issues.dbk b/en/issues.dbk
index 2edb9838..9d7ae1ae 100644
--- a/en/issues.dbk
+++ b/en/issues.dbk
@@ -203,33 +203,28 @@ $ sudo update-initramfs -u
<!-- stretch to buster -->
<title>Module configuration for bonding and dummy interfaces</title>
<para>
- Administrators who are using channel bonding and/or dummy
- interfaces (for instance to configure a machine as a router), and
- who have set up module parameters in a file under
- <filename>/etc/modprobe.d</filename>, may need to change the name
- of the local configuration file used, to avoid these parameters
- being ignored after the upgrade to buster.
- </para>
- <para>
- In buster, <systemitem role="package">udev</systemitem> ships a
- file <filename>/lib/modprobe.d/systemd.conf</filename> designed to
- make it easier to configure such interfaces using
- <command>systemd-networkd</command>. This contains the lines
+ Systems using channel bonding and/or dummy interfaces, for instance to
+ configure a machine as a router, may encounter problems upgrading to buster.
+ New versions of <systemitem role="package">systemd</systemitem> install a
+ file <filename>/lib/modprobe.d/systemd.conf</filename> (intended to
+ simplify configuration via <command>systemd-networkd</command>) which
+ contains the lines
</para>
<screen>
options bonding max_bonds=0
options dummy numdummies=0
</screen>
<para>
- A file in <filename>/lib/modprobe.d</filename> can be overridden by
- one with the same name under <filename>/etc/modprobe.d</filename>,
- but the names are processed in alphabetical order, so
- <filename>/lib/modprobe.d/systemd.conf</filename> follows and
- overrides (for instance)
- <filename>/etc/modprobe.d/dummy.conf</filename>. Make sure that any
- local configuration file has a name that sorts after
- <quote><filename>systemd.conf</filename></quote>, such as
- <quote><filename>/etc/modprobe.d/zz-local.conf</filename></quote>.
+ Admins who were depending on different values will need to ensure they are
+ set in the correct way to take precedence. A file in
+ <filename>/lib/modprobe.d</filename> can be overridden by one with the
+ same name under <filename>/etc/modprobe.d</filename>, but the names are
+ processed in alphabetical order, so
+ <filename>/lib/modprobe.d/systemd.conf</filename> follows and overrides
+ (for instance) <filename>/etc/modprobe.d/dummy.conf</filename>. Make sure
+ that any local configuration file has a name that sorts after
+ <quote><filename>systemd.conf</filename></quote>, such as
+ <quote><filename>/etc/modprobe.d/zz-local.conf</filename></quote>.
</para>
</section>
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