From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.io/gmane.comp.sysutils.supervision.general/2440 Path: news.gmane.org!.POSTED!not-for-mail From: "Laurent Bercot" Newsgroups: gmane.comp.sysutils.supervision.general Subject: Re: Can s6 be enough?: was s6-ps Date: Sat, 05 Jan 2019 21:22:13 +0000 Message-ID: References: <9f647c4c-2dc3-b977-928c-ee164ba88afe@ntlworld.com> <20190105153028.28bc0bab@mydesk.domain.cxm> Reply-To: "Laurent Bercot" NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="------=_MB4BD13F65-74EB-4DFD-8CF4-30F0B66645C5" X-Trace: blaine.gmane.org 1546723206 30907 195.159.176.226 (5 Jan 2019 21:20:06 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 5 Jan 2019 21:20:06 +0000 (UTC) User-Agent: eM_Client/7.2.33939.0 To: "Steve Litt" , supervision@list.skarnet.org Original-X-From: supervision-return-2030-gcsg-supervision=m.gmane.org@list.skarnet.org Sat Jan 05 22:20:02 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 4.84_2) (envelope-from ) id 1gftMQ-0007x6-IE for gcsg-supervision@m.gmane.org; Sat, 05 Jan 2019 22:20:02 +0100 Original-Received: (qmail 32256 invoked by uid 89); 5 Jan 2019 21:22:40 -0000 Mailing-List: contact supervision-help@list.skarnet.org; run by ezmlm Original-Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 32249 invoked from network); 5 Jan 2019 21:22:40 -0000 In-Reply-To: <20190105153028.28bc0bab@mydesk.domain.cxm> X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrgedtledrvdefgdduhedtucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecupfgfoffgtffkveetuefngfdpqfgfvfenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvufffkfgjfhhrfgggtgesrgdtreertderjeenucfhrhhomhepfdfnrghurhgvnhhtuceuvghrtghothdfuceoshhkrgdqshhuphgvrhhvihhsihhonhesshhkrghrnhgvthdrohhrgheqnecuffhomhgrihhnpehfohhsuggvmhdrohhrghenucfrrghrrghmpehmohguvgepshhmthhpohhuthenucevlhhushhtvghrufhiiigvpedt Xref: news.gmane.org gmane.comp.sysutils.supervision.general:2440 Archived-At: --------=_MB4BD13F65-74EB-4DFD-8CF4-30F0B66645C5 Content-Type: text/plain; format=flowed; charset=utf-8 Content-Transfer-Encoding: quoted-printable >Everybody appreciates the preceding two features, but personally, I >don't think they're absolutely necessary. Runit has neither, yet it >works just fine for most things. It really depends on what "most things" are. Small, server-only appliances? sure. Distributions where you can start all the oneshots first and all the longruns later? sure, but there aren't many of those. Typically udevd is a daemon you want to bring up very early, before some oneshots; so in the runit model, what do you do with udevd? Void Linux, which uses runit as its init system, has an answer to that: it doesn't supervise udevd. Don't you think that's ugly? Because I think that's ugly. >So I'm thinking that although process ordering and intermixing are >features we'd everyone likes, all but the most discerning among us >could get along without them and therefore init with s6 alone. Well yes. You can even get along with no supervision at all. Most people got along with sysvinit and sysv-rc just fine. The question is, do you want to? What do you expect from your init system? what functionality do you want to have, what functionality do you want your distribution to provide? > My opinion is one can boot just fine with s6 alone, as long as >you're willing to forego startup ordering and intermixing of longruns >and oneshots, which by definition a runit fan is. Yes, it can be done. As a matter of fact, it's completely trivial to take a Void Linux distribution and replace runit with s6. It works flawlessly. It just hasn't been done in the official Void distribution yet because the Void maintainers have other priorities, and runit works well enough for them. s6-rc and anopa exist for the people who are *not* willing to forego intermixing of longruns and oneshots. It all depends on what your priorities are, of what the aim of your distribution is. >So what do you all think? Is s6 a useful init system without s6-rc? Terminology, please! s6 isn't an init system per se. It's a process supervision system; and s6-rc is a service manager, aka machine state manager. Those are _components_ of an init system. You can build a complete, full-featured init system with s6 and s6-rc. You can also build an init system with s6 alone (and some scripting as s6-linux-init does), but it won't include a service manager. It's your call, really: I provide the mechanisms, distributions provide the policy. When they don't utterly give up on their duties, obviously. If you haven't watched it yet, please take a look at this video: https://archive.fosdem.org/2017/schedule/event/s6_supervision/ It's only 15 minutes long and explains all the terminology. -- Laurent --------=_MB4BD13F65-74EB-4DFD-8CF4-30F0B66645C5--