On Wed, Mar 16 2016, Benjamin Coddington wrote: >> 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@xxxxxxxxxx> >> >> >> >> 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. > > Yep.. that appears to work just fine. Seems like a simpler solution than > this change. It appears to me ( from systemd.service(5) ) that systemd's > state transitions for Type=Oneshot will avoid races that might overwrite the > environment file. Nice find! > Great. Thanks for testing and thanks for prodding me to explain myself. Very happy with the outcome! I've posted a patch to Steve. NeilBrown
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