Re: [PATCH nfs-utils] systemd: remove the nfs-config service

[NeilBrown <nfbrown@novell.com>]

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On Wed, Mar 16 2016, Benjamin Coddington wrote:

> On Wed, 16 Mar 2016, NeilBrown wrote:
>
>> On Sat, Mar 12 2016, Benjamin Coddington wrote:
>>
>> > The nfs-config service exists to translate distro-specific startup
>> > configuration into the command line arguments used by systemd to start nfs
>> > utilities.  Unfortunately, it is not clear to most users that this service
>> > must be recycled every time startup configurations have been modified, as
>> > this requirement is a change for at least one distro.
>> >
>> > We can get rid of nfs-config by generating the startup arguments in an
>> > ExecStartPre option for each service that needs them.  We'll also have to
>> > break out the EnvironmentFile into a separate file for each service to
>> > avoid races overwriting this file.
>> >
>> > A distro taking this change should also modify their
>> > /usr/lib/systemd/scripts/nfs-utils_env.sh script to include the new
>> > EnvironmentFile location for each service.
>> >
>> > Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
>>
>> I can't say I really like this, but it does make sense and solves a real
>> problem.
>> Maybe: I would never have written it myself, but I'm kind-a glad you did
>> :-)
>
> Which bits are unlikeable?  I am guessing that all these little intermediate
> files are the issue; that is what I hate.  I admit that it is a least-effort
> approach to fixing the problem.  What does the ideal fix look like to you?

I don't like having multiple intermediate config files that are all
identical, and I don't like having to run the config script every time
any daemon is (re)started.

I'm not sure what "ideal" would be.

One improvement would be if systemd could be given an executable in
place of an environment file with the implication that it would run the
executable and read environment variables from the stdout.
That would remove the multiple config files.
It would still mean the script is run every time, but I could be
convinced that isn't so bad.

An alternate idea is that maybe systemd could have a directive so that
in any transaction were "this" unit is started, "that" unit will also be
started.  Then we could replace "Wants=nfs-config.server" with
"Prepare=nfs-config.service" so if systemd ever needed to start any
nfs-related service, it would make preparations by first running
nfs-config.service - only once per transaction.

But unless you want to hack on systemd, I think what you have is good
enough.


.... hmmm.  I wonder what would happen if we just removed
"RemainAfterExit=y" from nfs-config.service.  Would it cause things to
fail, or would it cause nfs-config.service to be run every time.

Hey, that looks like it works!  Can you double check for me?
i.e. revert your patch, remove "RemainAfterExit=y" from
nfs-config.service, and then see if nfs-config.service gets run any time
any nfs server is started.

Thanks,
NeilBrown


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