freebsd stable - Mar 2015 - There has to be a better way of merging /etc during a major freebsd-update

Quoth Peter Olsson <list-freebsd-stable at
jyborn.se>:
>
> (But I will try running freebsd-update without merging /etc,
> and use mergemaster -F instead. Should solve my problem.)
I'm fairly sure this won't do what you want, and in fact won't work
at
all, unless your /etc is identical to the stock /etc installed from the
ISO. (Which it isn't, of course.)

installworld specifically avoids installing the files in /etc; then,
when you run mergemaster, it installs the new versions of those files
into a temporary directory and merges them with the existing /etc. 

freebsd-update works a little differently: because it doesn't have a
source tree available, it has to fetch the stock versions of the files
in /etc for the release you're upgrading from, so that it can patch them
to the new release and then merge the changes into your current /etc. If
you tell freebsd-update to install /etc without merging it will blindly
update files you haven't changed (which is probably what you want) but
(I think) will fail to update the files that you have changed, because
it uses binary patches which won't apply to your modified versions.

If you want a rather hackish solution, you could try something like
this:

    - Rename /etc to /oldetc.
    - Find yourself a copy of the stock /etc for the version you are
      upgrading from. (tar -xpf base.txz --include /etc)
    - Run freebsd-update with /etc removed from the merge list. This
      will (should?) give you a stock /etc for the version you are
      upgrading to.
    - Rename /etc -> /tmp/etc, /oldetc -> /etc and run mergemaster with
      -t /tmp.

Obviously I would script this if I was doing more than one or two
machines.

Ben

On Tue, Mar 10, 2015 at 10:06:37PM +0000, Ben Morrow
wrote:
> Quoth Peter Olsson <list-freebsd-stable at jyborn.se>:
> >
> > (But I will try running freebsd-update without merging /etc,
> > and use mergemaster -F instead. Should solve my problem.)
> 
> I'm fairly sure this won't do what you want, and in fact won't
work at
> all, unless your /etc is identical to the stock /etc installed from the
> ISO. (Which it isn't, of course.)
> 
> installworld specifically avoids installing the files in /etc; then,
> when you run mergemaster, it installs the new versions of those files
> into a temporary directory and merges them with the existing /etc. 
> 
> freebsd-update works a little differently: because it doesn't have a
> source tree available, it has to fetch the stock versions of the files
> in /etc for the release you're upgrading from, so that it can patch
them
> to the new release and then merge the changes into your current /etc. If
> you tell freebsd-update to install /etc without merging it will blindly
> update files you haven't changed (which is probably what you want) but
> (I think) will fail to update the files that you have changed, because
> it uses binary patches which won't apply to your modified versions.
> 
> If you want a rather hackish solution, you could try something like
> this:
> 
>     - Rename /etc to /oldetc.
>     - Find yourself a copy of the stock /etc for the version you are
>       upgrading from. (tar -xpf base.txz --include /etc)
>     - Run freebsd-update with /etc removed from the merge list. This
>       will (should?) give you a stock /etc for the version you are
>       upgrading to.
>     - Rename /etc -> /tmp/etc, /oldetc -> /etc and run mergemaster
with
>       -t /tmp.
> 
> Obviously I would script this if I was doing more than one or two
> machines
> 
> Ben
I'm not really clear on what will happen if I remove /etc/ from
MergeChanges in freebsd-update.conf. Will my /etc then be ignored
by freebsd-update, or will my /etc be completely overwritten by
freebsd-update?

Anyway, your hack could be useful to me. There are no more than
about ten files I usually change in /etc, so saving the current
/etc, installing a stock /etc, running freebsd-update and then
running diff -r to sort out my changes could work. But I'm a
little worried about removing my /etc changes from a running server.

Thanks!

Peter Olsson