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Why systemd?

blog.jorgenschaefer.de

121–130 of 263 posts

Re: Why systemd?

#121
post #8
post #4

The reason people use UNIX-like systems is because they work reliably. In order to make a complex system work reliably, it needs to be easily fixed. In order to fix a system, a person needs to understand it as well as be able to make a change in it. And in order to understand a system, it helps very much if that system is straightforward and lucidly verbose. I hope systemd will live or die on its merits; I fear that…

> In order to fix a system, a person needs to understand it as well as be able to make a change in it. So if I follow you, it would be easier to grok the whole system if all the code was in different places?

Yes. See "decoupling", "big ball of mud".

Re: Why systemd?

#122
post #42

Lots of people do not seem to understand the criticism of systemd. systemd = init system + a whole lot of other things. When people complain about systemd,they usually do not complain about what it does or how it does it in the init system part.That part is pretty solid as far as functionality is concerned. When people complain about systemd,they usually complain about the "whole lot of other things" part.Lots of peo…

This init process debate has brought out one of the worst elements of people in the FOSS community: treating some FOSS technology as an extension of their identity. Let's keep some perspective here. We are literally just talking about an init system. There are many others you can use. systemd is not taking away your freedom in any meaningful sense of the word "freedom". Debates should be about the technical merits of…

> systemd is not taking away your freedom in any meaningful sense of the word "freedom"

Systemd has made it impossible for me to run an up-to-date Gnome on FreeBSD. That feels a lot like taking away my freedom.

Re: Why systemd?

#123

Earlier quoted context omitted.

This. The FreeBSD rc system just works, is well documented and is small enough to understand by one person without too much effort.

Are there reasons why Linux couldn't just adopt it?

Slackware uses exactly this system.

Re: Why systemd?

#124

Earlier quoted context omitted.

Well said. I recently migrated to FreeBSD after trying sytemd on Arch and seeing that Debian and Ubuntu are planning to move too. The dead simple rc.conf file seems so much nicer than the stuff I was dealing with in the entire world of Linux-based systems, like going back to the way Arch used to be when I really liked it.

This. The FreeBSD rc system just works, is well documented and is small enough to understand by one person without too much effort.

As an init system it works fine, but you do end up having to find or invent a bunch of additional stuff if you want similar functionality to what's driving some of the systemd use-cases. The result might still be better (I haven't done a detailed architectural comparison), but you do need something. For example one of the things I find useful about the "systemd way" of things is that it provides, finally, a story about how to apply cgroups to services in a sane way. The kernel provides the APIs, but actually using them from userspace was not fun previously, with multiple incompatible systems, largely based on tangles of shell scripts that had broken corner cases.

With FreeBSD, my impression is that manual shell scripting is still the norm. Integrating RCTL (FreeBSD's resource-limiting facility) with service management basically consists of manually writing in a bunch of imperative calls to RCTL into scripts. There's no way to configure services with limits declaratively, ensure the right thing happens when services are started/stopped, etc., precisely because there's no integration between the RCTL facility and the process-management or init facilities. Or at least I haven't found a way. The closest is that if you need such integration only for jails, you do have the option of third-party "monolithic" management systems, such as CBSD.

Re: Why systemd?

#125
post #8
post #4

The reason people use UNIX-like systems is because they work reliably. In order to make a complex system work reliably, it needs to be easily fixed. In order to fix a system, a person needs to understand it as well as be able to make a change in it. And in order to understand a system, it helps very much if that system is straightforward and lucidly verbose. I hope systemd will live or die on its merits; I fear that…

> In order to fix a system, a person needs to understand it as well as be able to make a change in it. So if I follow you, it would be easier to grok the whole system if all the code was in different places?

The code is necessarily in different places, whether it's within a project or between projects. The difference is having an API that can be found without having to read all the code, and is well-defined and somewhat stable.

It's very "UNIX" to implement things as communicating processes rather than RPC or procedure-call-within-monolith.

Re: Why systemd?

#126
Case in point .. today .. rebuilding an X11 desktop system on Gentoo, some weird set of dependencies around gnome beneath the window manager wants to pull in systemd. I finally work out a way around it, but it wastes half an hour of my time.

My take: Containers are not well managed by general, daemon-oriented process supervisors with a localhost-oriented purview. However, those supervisors would do well to use container-related features to better secure and manage daemons as appropriate. In future, processes will be more likely managed across clusters by parallel capable supervisory systems with high availability goals and network infrastructure configuration, load and topology knowledge. Less and less people will even see the init system, except perhaps behind a logo or as it flashes past while booting their device in debug mode.

(Edit: stumbled on http://www.gossamer-threads.com/lists/gentoo/user/284741 which explains the scenario .. would hate to be on BSD)

Re: Why systemd?

#127
post #119
post #108

Earlier quoted context omitted.

There's nothing stopping a Linux distro doing this.... but It would be a step backwards: it is simpler, and does less stuff, so booting would be slower and some features are missing.

Why would booting be slower ? My BSD systems boot quickly enough for me.

My FreeBSD system has a 30-second timeout during which the entire boot process is halted because it waits for a default route to the internet... which it won't get, because I haven't configured one.

It's pretty dumb, and not enough of a problem for me that I'd figure out how to work around it, but it's a pretty good example.

Re: Why systemd?

#128
post #101
post #40

Earlier quoted context omitted.

Simple scripts? Have you looked at the shit in /etc/init.d in a modern linux distribution? $ wc -l * | sort -n | tail 274 exim4 286 apache2 290 dnsmasq 298 nfs-common 350 clamav-freshclam 364 udev 386 checkroot.sh 420 clamav-daemon 465 clamav-milter 9893 total If you look into these, you'll find tons of near-duplicate code between scripts, and frequently every script reinvents the wheel in one way or another.

Yes, modern linux and sysvinit are pigs compared to some alternatives (though systemd is worse). The choice isn't a binary choice between sysvinit and systemd. How about this? init + rc + all the scripts combined are smaller than your handful of daemon-specific scripts. And I understand exactly how all of this works (the kernel parts included). I can easily change any part of it, I can easily debug any part of it, I…

I think you also need to count the Bash source code there.

Re: Why systemd?

#129
post #115
post #85

Earlier quoted context omitted.

Whether it's all in pid 1 or not is irrelevant. What matters is that it has a monolithic architecture, whereby breakage in any one part or their communication channels can bring down the whole system. This is not just a theoretical concern; it has REPEATEDLY happened.

From experience with Linux init scripts, I'm far less concerned about systemd than SysV-init style boot processes, to be honest. I lost track of the number of boot issues related to poorly written init scripts I've dealt with many years ago.

I have an anecdote that occurred a short while while ago. We had a server with several database instances (with their own init scripts) running on it.

The scripts were buggy in such a way that starting the database would bring it up okay, but prevent the rest of the instances from starting. Also, using the "stop" directive would successfully stop the database... and all the others, as well.

The bug probably occurred because the init scripts were horrible to begin with and had been copied (ugh) to accommodate more instances, without the necessary modifications to not screw things up.

Re: Why systemd?

#130
post #122
post #42

Earlier quoted context omitted.

This init process debate has brought out one of the worst elements of people in the FOSS community: treating some FOSS technology as an extension of their identity. Let's keep some perspective here. We are literally just talking about an init system. There are many others you can use. systemd is not taking away your freedom in any meaningful sense of the word "freedom". Debates should be about the technical merits of…

> systemd is not taking away your freedom in any meaningful sense of the word "freedom" Systemd has made it impossible for me to run an up-to-date Gnome on FreeBSD. That feels a lot like taking away my freedom.

There's legal freedom, and there's practical freedom. Sadly, the latter is seldom talked about.

You can be stuck in a maze, in a pit or under a tree trunk. You're legally free, since no law or copyright license is saying may not get out. Yet, you're stuck and if you can't get out, you're not free at all.

When it comes to software, it is the size, complexity and complicated interdependencies that make the maze. As the system grows, an individual's practical freedom erodes. For instance, I complain about the web a lot. Even with a browser's source code and a permissive free license, there's close to nothing I can change about it in practice. It would be far too much work for me to maintain millions of lines of code and remain compatible and interoperable with a huge, fast-changing stack of technology... and the more you diverge, the harder it becomes. It's an uphill battle, and at some point you have to give up if you're not the giant. So the four software freedoms are reduced to two (or less). In practice I don't have the freedom to do what I want.

I think the FSF's stance of reducing freedom to a merely ethical issue is alarming. How would Dr. Stallman have felt if he had gotten his printer driver with a free license but so much code and complexity and dependency that it would've been impossible for him and a small team of hackers to actually port it and make it run on his system?

Of course, systemd alone is not approaching that level of complexity. Except that it's not only systemd.. the trend seems to be that all aspects of a modern OS are getting larger and more complicated. A little here, a little there, it all adds up and becomes a lot, everywhere. It's a sad trend.

There was a time when you could've picked up a book that pretty much describes all of your system's hardware at a low enough level so that you could start writing your own bootloader and OS from scratch, with the knowledge that you can interface with all the logical hardware devices. And it didn't take hundreds of thousands of lines of code. Now the amount of accumulated cruft we depend on is so large that the idea of writing your own not-a-toy OS is laughable...

Standing on the shoulders of a giant is necessary and helpful, but when you have to do too much of it, it stifles innovation and encourages monocultures.

I don't have anything against systemd per se; it doesn't represent my ideals, doesn't bring me features I want, and so I don't want to use it. If Ubuntu and Debian want to use it, they're of course free to do so. However, I am concerned that with the notion that "systemd has won", its proponents are going to assume it to be everywhere and build future software with the attitude that it is okay to depend on it -- who cares about the people who would prefer not to use it, let them suffer for disagreeing with the king!

Before the systemd rage, sysvinit might have been "the winner" on Linux in the sense that it was most widely used and supported. But we didn't have this sort of polarizing "sysvinit has won, fuck everyone and everything else" notion. Other distros with other init systems have happily coexisted all along, and these other distros haven't had to constantly fight a growing dependency on one specific init system.

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