Rootless docker support

[Dzeri96]

What happened?

I'm trying to run gefyra 1.0.2 on with rootless docker and the CLI seems to crash with the following stack trace:

Traceback (most recent call last):
  File "/home/redacted/.local/bin/gefyra", line 5, in <module>
    from gefyra.__main__ import main
  File "/home/redacted/.local/lib/python3.10/site-packages/gefyra/__main__.py", line 6, in <module>
    from gefyra.api import get_containers_and_print, get_bridges_and_print, GefyraStatus
  File "/home/redacted/.local/lib/python3.10/site-packages/gefyra/api/__init__.py", line 1, in <module>
    from .bridge import *  # noqa
  File "/home/redacted/.local/lib/python3.10/site-packages/gefyra/api/bridge.py", line 5, in <module>
    from gefyra.configuration import default_configuration
  File "/home/redacted/.local/lib/python3.10/site-packages/gefyra/configuration.py", line 233, in <module>
    default_configuration = ClientConfiguration()
  File "/home/redacted/.local/lib/python3.10/site-packages/gefyra/configuration.py", line 119, in __init__
    fcntl.ioctl(
OSError: [Errno 19] No such device

Since rootless docker does not support bridge networking, and therefore there is no docker0 interface present, ioctl throws this error.

What did you expect to happen?

The app not to crash I guess. To be honest I'm not sure if gefyra can work in this setup.

How can we reproduce it (as minimally and precisely as possible)?

Run docker in rootless mode and execute the gefyra client.

What Kubernetes setup are you working with?

$ kubectl version 
Client Version: version.Info{Major:"1", Minor:"26", GitVersion:"v1.26.1", GitCommit:"8f94681cd294aa8cfd3407b8191f6c70214973a4", GitTreeState:"clean", BuildDate:"2023-01-18T15:58:16Z", GoVersion:"go1.19.5", Compiler:"gc", Platform:"linux/amd64"}
Kustomize Version: v4.5.7
Server Version: version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.3", GitCommit:"434bfd82814af038ad94d62ebe59b133fcb50506", GitTreeState:"clean", BuildDate:"2022-10-25T19:35:11Z", GoVersion:"go1.19.2", Compiler:"gc", Platform:"linux/amd64"}

OS version

# On Linux:
$ cat /etc/os-release
PRETTY_NAME="Ubuntu 22.04.1 LTS"
NAME="Ubuntu"
VERSION_ID="22.04"
VERSION="22.04.1 LTS (Jammy Jellyfish)"
VERSION_CODENAME=jammy
ID=ubuntu
ID_LIKE=debian

$ uname -a
Linux retracted 5.15.0-60-generic #66-Ubuntu SMP Fri Jan 20 14:29:49 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

Anything else we need to know?

If this setup is not possible, I suggest a disclaimer be added to the documentation. Otherwise, what could we do to enable this functionality?

[SteinRobert]

Hey @Dzeri96 thank you very much for submitting your issue and helping us improving Gefyra!

You totally understood correctly what we're trying to access here! This code means to make the setup of Gefyra a bit more convenient. I suspect if you pass the --host flag with the dns name or ip of your cluster it will work. Something like this:
Get IP of one of your cluster nodes:

kubectl get nodes -o wide 

Run

gefyra up --host <IP>

Could you please check whether this actually helps you for the moment?
I will take this to the team and discuss how we could handle this issue a bit more gracefully.

[Dzeri96]

Hi, I've tried the suggested fix but unfortunately it does not seem to work.

[SteinRobert]

@Dzeri96 could you please provide the following information:
Your input, the output of the program and what kind of K8s provider you are using.
It would help a lot!

[Dzeri96]

@SteinRobert I can give you exact info in a few hours when I'm in front of my PC, but I'm using kind locally. Tried both the host/port from the kubectl config and the internal ip of the main (and only) node.

[SteinRobert]

No stress :)
Did you follow our kind getting started guide ?
It contains a configuration for kind to make sure port 31820 is actually reachable.

[Dzeri96]

@SteinRobert Just came home and I can confirm that I did create a kind cluster with the provided config. I don't know how to test reachability of this port but docker says that port forwarding is indeed enabled. If you would like to speed up debugging I can jump onto some kind of instant messaging platform.

[SteinRobert]

Alright - which version of kind are you using? I'll be available on the Unikube Slack during the week - we can certainly have a look at your issue there aswell.
unikubeworkspace.slack.com

[Dzeri96]

My kind version is 0.17.0. The workspace requires me to have a @blueshoe.de email address apparently?

[Schille]

@Dzeri96 we created a Discord server as a new communication channel. If you would like to join: https://discord.gg/Gb2MSRpChJ

[Schille]

The Gefyra client is currently depending on Docker overlay networks. It was a design decision to make the connectivity to a development machine as scoped as possible. This feature is not available with Docker rootless, though: https://docs.docker.com/engine/security/rootless/#known-limitations

If you're about to evaluate Gefyra, you may use Docker Desktop on Ubuntu. You will, however, sacrifice performance.
Unfortunately, I cannot see how we may support Docker rootless in the future, as we'd like to stay as close as possible to Kubernetes networking, even on the client side (which requires IP routing and a proper stack). We have to think about that, though.

A blog post about this (comparing Podman and Docker) will follow later this week picking up Docker rootless, too.

[Dzeri96]

Alright, thanks for the clarification. I'd be open to contribute but the issue is a bit over my head at the moment.

[SteinRobert]

Thanks @Schille for the input! So it seems we will not be able to support rootless Docker very soon. The overlay network functionality is currently essential for Gefyra itself. I will move this issue to discussion. Anyone looking for rootless docker support - we'd really appreciate signs like upvote and input on this.