From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1S95uQ-0003Pu-Lp for garchives@archives.gentoo.org; Sun, 18 Mar 2012 02:31:50 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 3944EE07D2; Sun, 18 Mar 2012 02:31:37 +0000 (UTC) Received: from mail-pz0-f53.google.com (mail-pz0-f53.google.com [209.85.210.53]) by pigeon.gentoo.org (Postfix) with ESMTP id DE897E0796 for ; Sun, 18 Mar 2012 02:30:25 +0000 (UTC) Received: by dady25 with SMTP id y25so9370879dad.40 for ; Sat, 17 Mar 2012 19:30:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=XXLqBSOPzgIT/KS6lmqFsqZBQnuSaSJE4MQShTPmnm0=; b=mvnhpf7m7m5I/Dcjw7bo41kkRAiytot6fKniFjV7Zh5zMKYLgJc9/yjg3TUS8jSEWs zNtpRFaNuhFpJpq+JPt5F/442i7so3iEECW1EmmeDyXhKlc7f+DToHuBClxH0mKT0ydb yn05j2BynOhP4fx80AnIMgdteaa9S9xIRY5SQYLMip4f4mFpKc0vjJ6xKuP3qakFCdBR MvUyx3fPgwg0Rmog9SLOPxLOJOEZd18I/jYOiLRBXSZJtiPHJQAUanVBJHLPz9xPWcFf lwdHlKwAoo1dLdKrl5JMhUOucZkFPQLJ7L2dnRnpMf5E/Xsa0q7hxqYLbRpnNi805tup +0Ig== Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org MIME-Version: 1.0 Received: by 10.68.125.195 with SMTP id ms3mr27183380pbb.62.1332037825089; Sat, 17 Mar 2012 19:30:25 -0700 (PDT) Received: by 10.68.197.41 with HTTP; Sat, 17 Mar 2012 19:30:25 -0700 (PDT) In-Reply-To: References: <709768995.843751.1331957483491.JavaMail.open-xchange@email.1and1.com> <20120317115300.GB3615@acm.acm> Date: Sat, 17 Mar 2012 20:30:25 -0600 Message-ID: Subject: Re: [gentoo-user] Re: systemd? [ Was: The End Is Near ... ] From: =?UTF-8?B?Q2FuZWsgUGVsw6FleiBWYWxkw6lz?= To: gentoo-user@lists.gentoo.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: e742d8f0-151e-49e3-8952-5b528f73b145 X-Archives-Hash: 5d5730c1e5dff6c6da3764d4575af845 On Sat, Mar 17, 2012 at 8:20 PM, Pandu Poluan wrote: > > On Mar 18, 2012 8:48 AM, "Canek Pel=C3=A1ez Vald=C3=A9s" wrote: >> >> On Sat, Mar 17, 2012 at 6:48 PM, Nikos Chantziaras >> wrote: >> > On 17/03/12 13:53, Alan Mackenzie wrote: >> >> >> >> Hello, Nikos. >> >> >> >> On Sat, Mar 17, 2012 at 08:25:48AM +0200, Nikos Chantziaras wrote: >> >> >> >>>> Happy Computer Users, systemd is on your horizon. >> >> >> >> >> >>> No, we don't. =C2=A0I hope systemd arrives soon. =C2=A0It's the best= init system >> >>> I >> >>> ever saw. >> >> >> >> >> >> What's so good about it? =C2=A0What will it do for me? >> >> >> >> I have this horrible sneaking suspicion that it will be more >> >> complicated >> >> than /sbin/init + OpenRC, just like udev + initramfs is more >> >> complicated >> >> than udev, and CUPS is more complicated than classical lpr. >> >> >> >> Why do you find it so good? >> > >> > >> > No idea. =C2=A0I only posted this because the OP didn't say what's bad= about >> > systemd :-) =C2=A0I really don't know I should care whether my system = runs >> > OpenRC >> > or systemd. >> >> Take this with a grain (or a kilo) of salt, since I'm obviously >> biased, but IMHO this are systemd advantages over OpenRC: >> >> * Really fast boot. OpenRC takes at least double the time that systemd >> does when booting, easily verifiable. In my laptop systemd is twice as >> fast as OpenRC; in my desktop is three times faster. >> >> * Really parallel service startup: OpenRC has never been reliable on >> parallel service startup; its documentation says it explicitly. >> >> * Really simple service unit files: The service unit files are really >> small, really simple, really easy to understand/modify. Compare the 9 >> lines of sshd.service: >> >> $ cat /etc/systemd/system/sshd.service >> [Unit] >> Description=3DSSH Secure Shell Service >> After=3Dsyslog.target >> >> [Service] >> ExecStart=3D/usr/sbin/sshd -D >> >> [Install] >> WantedBy=3Dmulti-user.target >> >> with the 84 of /etc/init.d/sshd (80 without comments). >> >> * Really good documentation: systemd has one of the best >> documentations I have ever seen in *any* project. Everything (except >> really new, experimental features) is documented, with manual pages >> explaining everything. And besides, there are blog posts by Lennart >> explaining in a more informal way how to do neat tricks with systemd. >> >> * Really good in-site customization: The service unit files are >> trivially overrided with custom ones for specific installations, >> without needing to touch the ones installed by systemd or a program. >> With OpenRC, if I modify a /etc/init.d file, chances are I need to >> check out my next installation so I can see how the new file differs >> from the old one, and adapt the changes to my customized version. >> >> * All the goodies from Control Groups: You can use kernel cgroups to >> monitor/control several properties of your daemons, out of the box, >> almost no admin effort involved. >> >> * It tries to unify Linux behaviour among distros (some can argue that >> this is a bad thing): Using systemd, the same >> configurations/techniques work the same in every distribution. No more >> need to learn /etc/conf.d, /etc/sysconfig, /etc/default hacks by >> different distros. >> >> * Finally, and what I think is the most fundamental difference between >> systemd and almost any other init system: The service unit files in >> systemd are *declarative*; you tell the daemon *what* to do, not *how* >> to do it. If the service files are shell scripts (like in >> OpenRC/SysV), everything can spiral out of control really easily. And >> it usually does (again, look at sshd; and that one is actully nicely >> written, there are all kind of monsters out there abusing the power >> that shell gives you). >> >> These are the ones off the top of my head; but what I like the most >> about systemd is that it just works, and that it makes a lot of sense >> (at least to me). >> >> Most of systemd features can be implemented in OpenRC (although the >> speed difference will never be eliminated if OpenRC keeps using shell >> files). My question is: why bother? systemd is already here, it >> already works, and it's actually supported in Gentoo. >> >> But again, remember that I'm biased: I keep an overlay to run Gentoo >> systems with only systemd; no OpenRC, no baselayout, no SysV. You guys >> can try it if you want: >> >> http://xochitl.matem.unam.mx/~canek/gentoo-systemd-only/ >> >> Usual disclaimer: I take no responsibility if using my overlay results >> in your systems asploding. That said, I'm using it on all my machines >> without a hitch. >> >> Regards. > > Interesting... > > However, what if the service is complex? For example, I created a "gatewa= ll" > service which, upon boot, initializes : > > * Routing tables and the RPDB > * ipset > * iptables > > while ensuring that upon shutdown, the settings of the above are > (optionally) saved. > > How do I specify such intelligence? Well, first of all you have options for starting a service, but also for stopping it. But besides that, please understand that while systemd does not use shell files *itself*, it doesn't stop you from using them if you so desire. In other words, put the "intelligence" on a script: /usr/local/bin/my-really-smart-and-complex-script.sh With proper execution settings (i.e., chmod 755 and with "#!/bin/sh" shebang), and then add a service file that exec's that: # cat /etc/systemd/system/mycomplexscript.service [Unit] Description=3DMy complex script After=3Dbasic.target [Service] ExecStart=3D/usr/local/bin/my-really-smart-and-complex-script.sh Then you only run: # systemctl daemon-reload And you start your script with: # systemctl start mycomplexscript.service If you want to enable it by default, add a link to it in /etc/systemd/system/multi-user.target.wants, or add an install section: [Install] WantedBy=3Dmulti-user.target And enable it with systemctl (after daemon-reload again): # systemctl enable mycomplexscript.service systemd doesn't stop you from using scripts. But, if the service is properly designed, it shouldn't be necessary. For example, you could probably break your complex script in small service unit files, and make them depend among each other, so the correct startup sequence is achieved. Check the docs, it's really amazing. Regards. --=20 Canek Pel=C3=A1ez Vald=C3=A9s Posgrado en Ciencia e Ingenier=C3=ADa de la Computaci=C3=B3n Universidad Nacional Aut=C3=B3noma de M=C3=A9xico