From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.comp.sysutils.supervision.general/2558 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: "Laurent Bercot" Newsgroups: gmane.comp.sysutils.supervision.general Subject: Re: interesting claims Date: Wed, 01 May 2019 18:13:53 +0000 Message-ID: References: <11997211556565598@myt6-27270b78ac4f.qloud-c.yandex.net> <20190501033355.6e41e707@mydesk.domain.cxm> Reply-To: "Laurent Bercot" Mime-Version: 1.0 Content-Type: text/plain; format=flowed; charset=utf-8 Content-Transfer-Encoding: quoted-printable Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="189144"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: eM_Client/7.2.34711.0 To: supervision@list.skarnet.org Original-X-From: supervision-return-2148-gcsg-supervision=m.gmane.org@list.skarnet.org Wed May 01 20:13:01 2019 Return-path: Envelope-to: gcsg-supervision@m.gmane.org Original-Received: from alyss.skarnet.org ([95.142.172.232]) by blaine.gmane.org with smtp (Exim 4.89) (envelope-from ) id 1hLtj3-000mzU-Ac for gcsg-supervision@m.gmane.org; Wed, 01 May 2019 20:13:01 +0200 Original-Received: (qmail 11891 invoked by uid 89); 1 May 2019 18:13:26 -0000 Mailing-List: contact supervision-help@list.skarnet.org; run by ezmlm Original-Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Original-Received: (qmail 11884 invoked from network); 1 May 2019 18:13:26 -0000 In-Reply-To: <20190501033355.6e41e707@mydesk.domain.cxm> Xref: news.gmane.org gmane.comp.sysutils.supervision.general:2558 Archived-At: >So Laurent's words from http://skarnet.org/software/s6/ were just part >of a very minor family quarrel, not a big deal, and nothing to get >worked up over. This very minor family quarrel is the whole difference between having and not having a 100% reliable system, which is the whole point of supervision. Yes, obviously sinit and ewontfix init are greatly superior to systemd, sysvinit or what have you. That is a low bar to clear. And the day we're happy with low bars is the day we start getting complacent and writing mediocre software. Also, you are misrepresenting my position - this is not the first time, and it's not the first time I'm asking you to do better. I've never said that the supervision had to be done by pid 1, actually I insist on the exact opposite: the supervisor *does not* have to be pid 1. What I am saying, however, is that pid 1 must supervise *at least one process*, which is a very different thing. s6-svscan is not a supervisor. It can supervise s6-supervise processes, yes - that's a part of being suitable as pid 1 - but it's not the same as being able to supervise any daemon, which is much harder because "any daemon" is not a known quantity. Supervising a process you control is simple; supervising a process you don't know the behaviour of, which is what the job of a "supervisor" is, is more complex. In future presentations, I will make sure to pinpoint the difference. Yes, that is a detail, but this detail is what allows us to make pid 1 both simple (not having the whole supervision logic in pid 1) and correct (covering the case where all processes die). -- Laurent