Systemd vs. Docker • Hacker News Board

Re: Systemd vs. Docker

#21

Post by laumars » Thu, Mar 03, 2016, 4:05 PM UTC

xaduha wrote: post #8

jimktrains2 wrote: post #5

Earlier quoted context omitted.

Or they can move to one of the BSDs and use jails which are much more stable, secure, and tested than linux containers.

Technology isn't that important here, it's what stems from it is. Adoption, infrastructure, tools, community. There's also a price for doing it differently. And believe you me, using BSD nowadays is the definition of doing things differently. What for? What I'm getting for losing my time and reinventing the tools that are already available and much more polished? Dockerfiles can be replicated. Docker Hub can be repli…

You do realise that "different" platforms can still be popular enough to have a lot of the same ecosystems. Hell, Docker itself used to be the "alternative"; not even that long ago in fact.

FreeBSD might only have a fraction of the community that Linux does, but that's still a pretty large number of developers and sysadmins in real world terms.

Disclosure: I run both FreeBSD and Linux systems.

Re: Systemd vs. Docker

#22

Post by atemerev » Thu, Mar 03, 2016, 4:06 PM UTC

pas wrote: post #16

thwarted wrote: post #13

Poettering says that PID 1 has special requirements. One of these is killing "zombie" processes that have been abandoned by their calling session. This is a real problem for Docker since the application runs as PID 1 and does not handle the zombie processes. For example, containers running the Oracle database can end up with thousands of zombie processes. Why does Poettering keep claiming this when he's the one who s…

I guess he's saying, that you can't just take any random binary and run it in a Docker container, because if that binary spawns a lot of children but does not wait for them, then you'll have a lot of zombies. Docker could run a minimal pid1 in each container to address this. Though if this had been a big issue I guess this would have been already fixed. Naturally, a proof of concept of the problem would be great. (Le…

Supervisord is the officially blessed solution:

https://docs.docker.com/engine/admin/using_supervisord/

Re: Systemd vs. Docker

#23

Post by xaduha » Thu, Mar 03, 2016, 4:06 PM UTC

protomyth wrote: post #14

xaduha wrote: post #8

Earlier quoted context omitted.

Technology isn't that important here, it's what stems from it is. Adoption, infrastructure, tools, community. There's also a price for doing it differently. And believe you me, using BSD nowadays is the definition of doing things differently. What for? What I'm getting for losing my time and reinventing the tools that are already available and much more polished? Dockerfiles can be replicated. Docker Hub can be repli…

That's basically the argument to use Windows and Windows-based technology and not Linux. Everything you can do on any of the UNIX boxes, you can do with Windows. It might be different, but it is still a more popular / supported platform. Since I'm not a Windows fan, I find value in doing it differently, and so have Linux fans. I think you will find FreeBSD and SmartOS users find the cost in time to bring a large enou…

> That's basically the argument to use Windows and Windows-based technology and not Linux.

Not today it isn't. Years, maybe decades ago it could be.

What Linux containers do is help to remove the barrier that various distributions introduced, it makes things more accessible and it's more lightweight than using virtualization. Centos, Alpine, Ubuntu, whatever. As long as it is in a container I can work with it. I can even run some Windows binaries with Wine inside a container. rkt is largely compatible with Docker infrastructure, so that too is fine.

But what jimktrains2 suggesting is complete opposite of that, it reduces options.

Re: Systemd vs. Docker

#24

Post by bryanlarsen » Thu, Mar 03, 2016, 4:08 PM UTC

atemerev wrote: post #20

bryanlarsen wrote: post #6

Earlier quoted context omitted.

Why the systemd hate? Because it's a big monolithic project that takes over your system? You do realize that Docker is much more monolithic and opinionated than systemd, right?

Opinionated, yes. Monolithic, no. Huge mess of everything that deeply integrates in any system — of course not, your containers don't need to know anything about Docker and host system, you are absolutely free in choices. It's even possible to run (gasp!) multiple services with supervision inside Docker.

That's the first time I ever heard anybody argue that Docker isn't monolothic. It does everything inside it's single daemon executable. Compare against Rocket, which doesn't use a daemon, and uses separate executables for different tasks and stages.

Re: Systemd vs. Docker

#25

Post by xaduha » Thu, Mar 03, 2016, 4:11 PM UTC

laumars wrote: post #21

xaduha wrote: post #8

Earlier quoted context omitted.

Technology isn't that important here, it's what stems from it is. Adoption, infrastructure, tools, community. There's also a price for doing it differently. And believe you me, using BSD nowadays is the definition of doing things differently. What for? What I'm getting for losing my time and reinventing the tools that are already available and much more polished? Dockerfiles can be replicated. Docker Hub can be repli…

You do realise that "different" platforms can still be popular enough to have a lot of the same ecosystems. Hell, Docker itself used to be the "alternative"; not even that long ago in fact. FreeBSD might only have a fraction of the community that Linux does, but that's still a pretty large number of developers and sysadmins in real world terms. Disclosure: I run both FreeBSD and Linux systems.

And your point is? A suggestion to switch to BSD and jails for an average user of Docker is laughable.

Re: Systemd vs. Docker

#26

Post by bryanlarsen » Thu, Mar 03, 2016, 4:14 PM UTC

atemerev wrote: post #17

I don't always run containerized applications, but when I do, I prefer them completely systemd-free, thank you. Sometimes I wonder if systemd is actually a part of big plan of moving everyone to microservices and containers and maybe even unikernels — anything, just anything without this abomination.

Can you explain your position to me? I can understand somebody who dislikes systemd and dislikes docker. I can understand somebody who likes both systemd and docker. But disliking systemd but liking docker? That I don't understand. Any effective criticism of systemd that I've heard generally can also be applied to docker.

Like yours: "I wonder if systemd is actually a part of big plan of moving everyone to microservices and containers and maybe even unikernels" works even better if you replace systemd with docker.

Re: Systemd vs. Docker

#27

Post by masklinn » Thu, Mar 03, 2016, 4:15 PM UTC

atemerev wrote: post #22

pas wrote: post #16

Earlier quoted context omitted.

I guess he's saying, that you can't just take any random binary and run it in a Docker container, because if that binary spawns a lot of children but does not wait for them, then you'll have a lot of zombies. Docker could run a minimal pid1 in each container to address this. Though if this had been a big issue I guess this would have been already fixed. Naturally, a proof of concept of the problem would be great. (Le…

Supervisord is the officially blessed solution: https://docs.docker.com/engine/admin/using_supervisord/

supervisord specifically documents that it's not an init and shouldn't be used as an init, that's the second paragraph of its home page: http://supervisord.org/index.html?highlight=init

Re: Systemd vs. Docker

#28

Post by baldfat » Thu, Mar 03, 2016, 4:18 PM UTC

JohnDoe365 wrote: post #9

jimktrains2 wrote: post #5

Earlier quoted context omitted.

Or they can move to one of the BSDs and use jails which are much more stable, secure, and tested than linux containers.

Or they can move to a steam engine which are much more stable, secure, and tested than cars consuming gasoline. Embrace the change, it's for a better future.

Poster of embrace the community.

They don't have to embrace the change they have other options. What bothers me is they chose to shoot down everything and anything that has systemd in it out in the public. Just leave the fight and just embrace your choice and allow others to have their choice and don't pee on their parade.

Re: Systemd vs. Docker

#29

Post by Wilya » Thu, Mar 03, 2016, 4:26 PM UTC

xaduha wrote: post #8

jimktrains2 wrote: post #5

Earlier quoted context omitted.

Or they can move to one of the BSDs and use jails which are much more stable, secure, and tested than linux containers.

Technology isn't that important here, it's what stems from it is. Adoption, infrastructure, tools, community. There's also a price for doing it differently. And believe you me, using BSD nowadays is the definition of doing things differently. What for? What I'm getting for losing my time and reinventing the tools that are already available and much more polished? Dockerfiles can be replicated. Docker Hub can be repli…

Have you used both jails and Docker? Saying docker is a much more polished option doesn't match my experience. Yes, it has more features, but with these features come more bugs. Some of them are minor annoyances. Some are of the "our infrastructure is fucked until we switch our storage driver" kind.

Sometimes, stability is a gain.

Re: Systemd vs. Docker

#30

Post by atemerev » Thu, Mar 03, 2016, 4:28 PM UTC

bryanlarsen wrote: post #26

atemerev wrote: post #17

I don't always run containerized applications, but when I do, I prefer them completely systemd-free, thank you. Sometimes I wonder if systemd is actually a part of big plan of moving everyone to microservices and containers and maybe even unikernels — anything, just anything without this abomination.

Can you explain your position to me? I can understand somebody who dislikes systemd and dislikes docker. I can understand somebody who likes both systemd and docker. But disliking systemd but liking docker? That I don't understand. Any effective criticism of systemd that I've heard generally can also be applied to docker. Like yours: "I wonder if systemd is actually a part of big plan of moving everyone to microservi…

Docker is just a toolkit for composing and networking layered OS images. It improves isolation of things and adheres to simple principles (immutable containers, restarting instead attempting to recover, etc.) It structures things better. Inter-container communication is deliberately simple (env variables and, recently, networking).

Systemd spits on isolation, it embraces integration of everything. Supervision, logging, communication, IO, configuration, state management — everything goes through systemd. Everything is binary and opaque. Docker is transparent.