Re: [RFC PATCH v4] ndctl: monitor: add ndctl monitor daemon

[Dan Williams <dan.j.williams@intel.com>]

On Thu, Mar 15, 2018 at 3:41 AM, Qi, Fuli <qi.fuli@jp.fujitsu.com> wrote:
>>>
>>> In this implemention, when a ndctl monitor starts with [--daemon] option, all
>>> the arguments will be saved into a temp file named as daemon-name and placed
>>> under /etc/sysconfig/ndctl/ directory. The temp file would be used as an
>>> EnvironmentFile by systemd, and it would be deleted automatically when the
>>> systemd service is stopped.
>>
>> The monitors started by hand should be kept separate from the monitors
>> started by systemd. The default monitor started by systemd should get
>> its configuration from /etc/ndctl.conf, and we should otherwise have a
>> --conf-file option to the monitor to override the default
>> configuration. Any other monitors started outside of the systemd
>> should remain independent.
>
> Thank you very much for your comments. I still have something unclear about
> how to manage ndctl monitor daemon. Let's clarify the specification of monitor daemon.
>
> I have the following questions.
>  a) About command line interface
>     1) I would like to confirm when a monitor daemon is launched  by using
>        command line interface with [--daemon] option (like # ndctl monitor
>        --dimm nmem1 --daemon), then how to manage it? (i.e. stop, check status)

I don't want to invent new policy here, how do other daemons behave
with respect to this, can you investigate? Use mdadm or dnsmasq as an
example.

>     2) When multiple daemons be running at same time, how can we recognize
>        each of them?

Process id.

>
>  b) About using systemctl command
>     3) Should we need to limit the maximum number of running daemons to be one?
>        If yes, I am thinking the option should support multiple values, then
>        users can modify the default configuration by using [--conf-file] option.
>        # ndctl monitor --dimm nmem1,nmem2 --conf-file
>
>     4) If multiple daemons can be running at the same time, multiple configuration
>        files named <daemon-name> are needed. Do you agree that let users create the
>        configuration file manually when they want to launch a monitor daemon?

Yes, we should always support a local configuration file in addition
to the default configuration.
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