Re: autodetecting init system.

[Owen Synge <osynge@suse.com>]

On 05/11/2015 06:37 PM, John Spray wrote:
> On 11/05/2015 17:29, Owen Synge wrote:
>> Dear all,
>>
>> Many init systems are used in linux now. Some ceph code needs to know
>> the init system. (I must admit I have not looked into Solaris, MacOS and
>> BSD and probably should have)
>>
>> It would be nice to have one function that detects the init system
>>
>> Since the init system can be specified in ceph and ceph-deploy
>> explicitly it seems to be its reasonable to fail clearly to detect init
>> system.
> I think I'm missing some background here.  I was under the impression
> that distros generally had a preferred init system (even if they let you
> switch), and if another is in use then compatibility links are usually
> provided (e.g. sysv-style calling through to systemd or vice versa). 
> Given that, the distro packaging then uses whatever the "right" way to
> start a service is for that distro, and it's up to the distro to make
> sure that command is available.

I am not sure that sysV can emulate systemd, but systemd can and does
emulate sysV by default on SUSE and I think also debian .

> Otherwise don't we descend into a kind of madness where a package
> post-install script can't start a service, because it doesn't know what
> command to run?

I have not yet tested converting ubuntu or debian latest releases with
non standard init systems (anything other than systemd).

The main reason is I do expect the exact "madness" you predict, that
said they claim support for this.

best regards

Owen