Re: Make etcupdate bootstrap requirement due to previous mergemaster usage more clear in handbook

On 12/3/21 6:09 PM, Tomoaki AOKI wrote:
> On Fri, 03 Dec 2021 05:54:37 -0800 (PST)
> "Jeffrey Bouquet" <jbtakk@iherebuywisely.com> wrote:
> 
>>
>>
>> On Fri, 3 Dec 2021 13:58:39 +0100, Miroslav Lachman <000.fbsd@quip.cz> wrote:
>>
>>> On 03/12/2021 12:52, Yetoo Happy wrote:
>>>
>>> [...]
>>>
>>>>   Quick Start* and follow the instructions and get to step
>>>> 7 and may think that even though etcupdate is different from mergemaster
>>>> from the last time they used the handbook they have faith that following
>>>> the instructions won't brick their system. This user will instead find that
>>>> faith in general is just a very complex facade for the pain and suffering
>>>> of not following *24.5.6.1 Merging Configuration Files* because the user
>>>> doesn't know that step exists or relevant to the current step and ends up
>>>> unknowingly having etcupdate append "<<<< yours ... >>>>> new" to the top
>>>> of the user's very important configuration files that they didn't expect
>>>> the program to actually modify that way when they resolved differences nor
>>>> could they predict easily because the diff format is so unintuitive and
>>>> different from mergemaster. Now unable to login or boot into single user
>>>> mode because redirections instead of the actual configuration is parsed the
>>>> user goes to the handbook to find out what might have happened and scrolls
>>>> down to find *24.5.6.1 Merging Configuration Files* is under *24.5.6.
>>>
>>> [...]
>>>
>>> That's why I think etcupdate is not so intuitive as tool like this
>>> should be and etcupdate is extremely dangerous because it intentionally
>>> breaks syntax of files vital to have system up and running.
>>> If anything goes wrong with mergemaster automatic process then your have
>>> configuration not updated which is almost always fine to boot the system
>>> and fix it. But after etcupdate? Much worse...
>>>
>>> I maintain about 30 machines for 2 decades and had problems with
>>> etcupdate many times. I had ti use mergemaster as fall back many times.
>>> Mainly because of etcupdate said "Reference tree to diff against
>>> unavailable" or "No previous tree to compare against, a sane comparison
>>> is not possible.". And sometimes because etcupdate cannot automatically
>>> update many files in /etc/rc.d and manual merging of a lot of files with
>>> "<<<< ==== >>>>" is realy painful while with mergemaster only simple
>>> keyboard shortcuts will solve it.
>>> All of this must be very stressful for beginners.
>>>
>>> So beside the update of documentation I really would like to see some
>>> changes to etcupdate workflow where files are modified in temporary
>>> location and moved to destination only if they do not contain any syntax
>>> breaking changes like <<<<, ====, >>>>.
>>>
>>> Kind regards
>>> Miroslav Lachman
>>
>>
>> Agree. I fell back to mergemaster this Nov on 13-stable when the /var files
>> pertaining to etcupdate were all missing current /etc data, and no study of
>> man etcupdate was clear enough to rectify such a scenario, and suspect my
>> initial use of etcupdate will or may require a planned reinstall,  not having
>> had to do so since Jan 2004 iirc,  [ vs failed hard disk migrations ] and
>> I am just hoping mergemaster stays in /usr/src and updated
>> for system changes, even if moved to 'tools' or
>> something, since its use seems intuitive and much less of a black box.
>> Also, /usr/src/UPDATING still at the bottom emphasizes mergemaster still.
>>
> 
> Not sure it's fixed or not (tooo dangerous to try...), -n (dry-run)
> option of etcupdate is now quite harmful. Maybe by any commit done in
> this april on main (MFC'ed to stable/13 in june).
> 
>   *I got busy manually checking and applying changes to /etc, and
>    forgot to file PR.
> 
> Doing `etcupdate -n` itself runs OK, but following `etcupdate -B` does
> NOT do anything, hence nothing is actually updated.
> The only workaround I have is NOT to try dry-run.

Humm.

> It would be because the same trees are used for dry-run and actual run.
> (Not looked into the code. Just a thought.)

So the new changes always build a temporary tree (vs trying to build
/var/db/etupdate/current in place).  For -n it should be that it just
doesn't change /var/db/etcupdate/current at the end, but if it did the
move anyway that would explain the bug you are seeing.  That does indeed
look broken.  Please file a PR as a reminder for me to fix it.

-- 
John Baldwin