Support Swarm mode / clarify its status

[chrisbecke]

Tell us about your request

Please clarify the status of Docker Swarm mode.

Which service(s) is this request for?

Docker Engine

Additional context

Docker swarm mode is an awesome container orchestrator. Swarmkit is still upstream in moby and being actively developed. However the larger zeitgeist is that swarm is deprecated and K8s should be used instead and consequently swarm mode is increasingly not being actively targeted by projects.

However, it is super simple to setup and get working compared to K8s. New features are being added to swarm(kit) like jobs - which look perfect as CI/CD runners or Server-less task runners. But, with the hesitancy that projects are showing in continuing to invest in swarm related features, I fear the world will lose the best little multi node orchestrator that could.

[ximon18]

Is this perhaps relevant: #86 ?

[chrisbecke]

nope. classic swarm was a - not sure what it was exactly actually - a kind of plug on orchestrator that presented as a single docker node. it was deprecated precisely because it was replaced with swarm mode.

[ximon18]

But doesn't that issue effectively answer this one? I.e. classic swarm is deprecated but swarm is still actively supported?

[chrisbecke]

Mirantis only committed to swarm until 2022 - understandable as they are a very K8s corporate facing solution provider and they target the space where that scale is needed.

Since that deal, every tech article covering swarm has basically stated that it's dead and its time for everyone to move to K8s. Which is stupid because swarmkit is part of moby and very much alive. But also accurate, because Mirantis got the corporate customers, who might have been using Swarm. Which means that literally no company is providing corporate level support for Docker Swarm.

However, on tonights "Docker Talks: Donnie Berkholz - Head of Product @ Docker" session, it was apparent that I am not the only person thinking that docker swarm is simple and effective and consequently deserves some attention to get it back in front of people as a viable option: there was near unanimous support amongst the chats participants for docker swarm.

So, swarm mode exists, and is actively developed. But as a devops / developer I cannot go to my boss and say it's a supported solution that we can build solutions on.
And projects like OpenFAAS, which literally started on swarm, have migrated to K8s and now don't recommend swarm for much at all.

[PavelSosin-320]

@chrisbecke Everything is fine except one blocker issue: Only Windows Ubuntu-20.04 WSL distro with K8s knows to use systemd and run Podman that is the real Docker engine replacement for the loosely connected laptops used as a development machine. Without systemd Podman is hardly useful and Docker startup suffers from instability too. But this is in Microsoft's hands.
RedHat already started pulling Docker support off from its Linux distros but Windows WSL CentOS8 and RHEL8 don't run Podman well. I didn't try yet other WSL distros. Ubuntu is ahead for today.

[aCandidMind]

Totally hooked on the great news that Mirantis is going to invest in swarm beyond 2022. They are expanding the SwarmKit team and adding new features (one has already hit moby master)
https://www.mirantis.com/blog/mirantis-will-continue-to-support-and-develop-docker-swarm/

The future of SwarmKit is fine, and @BretFisher talks about it on his show here: https://youtu.be/L5N43aQQArw

[decentral1se]

I do wonder where we're at now? I just read #194 (comment) 🤔

Still see some movement on https://github.com/moby/moby/pulls?q=is%3Aopen+is%3Apr+label%3Aarea%2Fswarm though 🙏

And then what of #194 (comment)?

[chrisbecke]

Just a personal comment from Dockercon'21 - the talks involving swam seemed to be well populated with people using, or thinking of using, swarm in production. The consensus opinion seemed to be that swarm was, for a number of use cases, more fit for purpose than K8s :- i.e. the simplicity of swarm over K8s allows a smaller team to deliver a more secure product with higher SLOs.
That said - officially there was no word on the state of the CSI volume driver support that Mirantis mentioned some time ago. Or any official word on swarm at all. So that is concerning.

[decentral1se]

A bug fix PR from Mirantis staff moby/swarmkit#3003 😱 What a cliff hanger!

[dperny]

@chrisbecke I'm actually working on CSI support right. Like, literally today still working on it. There have been delays, but at this point I'm hammering out the final API and CLI. It's very nearly completed.

[decentral1se]

@dperny you are a hero!!!

[tomposmiko]

Is there any update on the status of swarm?
As far as I can see, it looks exactly what we need, simple, lightweight, easy to manage, easy to run, easy the whole concept.

However, we do not jump on a track that is heading dead end.