help to do a patch to use systemctl/journalctl in docker VM ?

[Raizo62]

Hi

On LiveRaizo, i look to temporary transform the QEmu VM Debian in Docker VM.
so it will be lighter to use LiveRaizo in Virtualbox, for example.

But, in class room, i use often systemctl/journalctl to configure and debug service.
And, by default, systemctl doesn't work in docker.

To do it, the most easy method that i found is :

docker run --name centos.server -ti -d --privileged=true centos "/usr/sbin/init"
docker exec --tty --interactive centos.server /bin/bash

I have see that you afraid from risk here

I want to do a litlle patch on gns3 for LiveRaizo, but i didn't find the file where you are doing a "docker run" (the docker exec is in "gns3server/compute/docker/docker_vm.py")
Could you say the file or the function where i can add this : "--privileged=true" and "/sbin/init" ?
I hope that it is not more complicated.

[ghost]

In GNS3 the docker images are already started with the option --privileged=true. The /usr/sbin/init command can be added as the "Start command" in the docker template.

As /usr/sbin/init shows only some output, the console won't give you a shell allowing to enter commands. But you can use the auxiliary console (right-click on the node -> Auxiliary console) to get a shell window.

If you have experience with systemd you might be able to add a systemd configuration, that starts a shell on /dev/pts/0, the console device of the docker node. Then you might be able to use the regular node console also for shell access. But I don't have systemd knowledge and can't help you with that.

[ghost]

To answer your question about where to change the docker node creation (even though I don't think that's needed):

GNS3 uses the Docker API to interact with Docker, not the command line. The nodes creation is done in gns3server/compute/docker/docker_vm.py function create(). The params structure defines the default parameter for the docker node creation.

gns3-server/gns3server/compute/docker/docker_vm.py

Lines 331 to 348 in 03f8ea9

	params = {
	"Hostname": self._name,
	"Name": self._name,
	"Image": self._image,
	"NetworkDisabled": True,
	"Tty": True,
	"OpenStdin": True,
	"StdinOnce": False,
	"HostConfig": {
	"CapAdd": ["ALL"],
	"Privileged": True,
	"Binds": self._mount_binds(image_infos),
	},
	"Volumes": {},
	"Env": ["container=docker"], # Systemd compliant: https://github.com/GNS3/gns3-server/issues/573
	"Cmd": [],
	"Entrypoint": image_infos.get("Config", {"Entrypoint": []}).get("Entrypoint")
	}

[Raizo62]

Thank you @b-ehlers :-)

Your /usr/sbin/init in "Start command" works and asks me a login, then i doesn't need to use Auxiliary console :-)
I will investigate more

Thank you also for the Docker API information