Re: machine api to supervise

From: Laurent Bercot <>
Date: Thu, 24 Sep 2015 13:27:25 +0200

On 24/09/2015 12:56, e-mail j.deboynepollard-newsgroups wrote:
> Unless some daemontools-family
> developer goes and does something wrongheaded like breaking compatibility

  I did. There were good reasons for it: the way the bits are arranged in
the legacy daemontools status format is suboptimal, and getting the useful
information out of it requires a little extra work - and I got confused
a few times by the meaning of the bits.

  The status file was never an "official" interface, and the tools that
parse it are actually looking under the hood and breaking abstraction
layers. I'm surprised that you, of all people, advocate this procedure:
this is clearly bad programming practice.

> There is something wrong with processing the output of svstat, and you are
> right to be leery of doing so. The daemontools manual explicitly states that it
> is human readable, rather than machine-readable. And there are variations in the
> human-readable forms, which are fine for humans but no good for programs.

  Still, svstat is the only "official" interface, so for now it's the only
safe way to proceed. I agree that it is inconvenient, and that daemontools
should have provided a tool to get machine-readable status information;
but in the absence of such a tool, svstat is the entry point and should
be used as such.

  s6 provides a C API to read status: s6_svstatus_read(). The command-line
interface to it is s6-svstat. It's currently lacking options to output
machine-readable data; I plan to add that functionality, but in the
meantime, it *is* the interface.

Received on Thu Sep 24 2015 - 11:27:25 UTC

This archive was generated by hypermail 2.3.0 : Sun May 09 2021 - 19:44:19 UTC