Hello,

Currently there is no way to perform atomic store of configuration file. The persistence API of ovirtnode.ovirtfunctions can fail in many stages and leave system in unpredictable state.

I suggest an API like:

persist(file, destination)

1. cp file /config/destination.tmp
2. mv /config/destination.tmp /config/destination
3. rebind /config/destination destination

This way we have either the content of the new or old file.

---

BTW:

Looking at code, please try to do as much as you can in python. I don't understand the reason of calling system utilities such as:

system("mkdir -p /config/" + dirname)
->os.makedirs(os.path.join('/config', dirname))

system("rm -f /config"+ filename)
->shutil.rmtree(os.path.join('/config', dirname))

system_closefds("echo "+filename+" >> /config/files")
->with open('/config/files', 'a') as f:
    f.write("%s\n" % filename)

ret = system_closefds("grep -q \"^$" + filename +"$\" " + \
                " /config/files 2> /dev/null")
->with open('/config/files', 'r') as f:
    if filename in f:
        ....
etc...

Using python only reduces the blocks that can fail, provide better control on code flow and much better perform.

In these small cases you must call external program, please try to avoid system() as it may route output and input of caller which is an unexpected behaviour of an API. Use subprocess.Popen().

Thank you.