Getting panic error when trying with --network host

[rajeshkumaratappviewx]

I am new to k3d. When I tried to create a cluster using network option, (k3d cluster create my-cluster --network host), it fails with the below error. Without the network option cluster creation is working fine. The version details as follows

K3D_VERSION=v4.0.0
K3S_VERSION=v1.19.7+k3s1
K3D_TOOLS_VERSION=v4.0.0
RANCHER_PAUSE_VERSION=3.2
Docker version 19.03.13, build cd8016b6bc.
OS ="Ubuntu" (VERSION="20.04.2 LTS (Focal Fossa)")

Thanks for the help in advance.

The error is

INFO[0000] Network with name 'host' already exists with ID '737f4f9c410a52022750804dc69adf4dad40c2340cb114b01466b1b7ea6b8db0' 
...........
...........
...........
INFO[0005] (Optional) Trying to get IP of the docker host and inject it into the cluster as 'host.k3d.internal' for easy access 
**panic: runtime error: index out of range [0] with length 0**

goroutine 1 [running]:
**github.com/rancher/k3d/v4/pkg/runtimes/docker.GetGatewayIP**(0x1258620, 0xc000034098, 0x7ffe6ebaa26a, 0x4, 0x0, 0xc00024ce78, 0x4761c5, 0x1, 0x109e7e0)
	/drone/src/pkg/runtimes/docker/network.go:127 +0x218
github.com/rancher/k3d/v4/pkg/runtimes/docker.Docker.GetHostIP(...)
	/drone/src/pkg/runtimes/docker/host.go:34
github.com/rancher/k3d/v4/pkg/client.GetHostIP(0x1258620, 0xc000034098, 0x126cd40, 0x18bb018, 0xc00012b620, 0x10c6fc0, 0xc0005159e0, 0xc00024cf40, 0x6033ca, 0x0)
	/drone/src/pkg/client/host.go:51 +0x152
github.com/rancher/k3d/v4/pkg/client.prepInjectHostIP(0x1258620, 0xc000034098, 0x126cd40, 0x18bb018, 0xc00012b620)
	/drone/src/pkg/client/cluster.go:930 +0xd7
github.com/rancher/k3d/v4/pkg/client.ClusterRun(0x1258620, 0xc000034098, 0x126cd40, 0x18bb018, 0xc00012b600, 0x0, 0x1230040)
	/drone/src/pkg/client/cluster.go:97 +0x47c
github.com/rancher/k3d/v4/cmd/cluster.NewCmdClusterCreate.func1(0xc0001cd600, 0xc00017e9c0, 0x1, 0xc)
	/drone/src/cmd/cluster/clusterCreate.go:128 +0x51c
github.com/spf13/cobra.(*Command).execute(0xc0001cd600, 0xc00017e900, 0xc, 0xc, 0xc0001cd600, 0xc00017e900)
	/drone/src/vendor/github.com/spf13/cobra/command.go:854 +0x2c2
github.com/spf13/cobra.(*Command).ExecuteC(0x187af80, 0xc000030100, 0xe, 0xe)
	/drone/src/vendor/github.com/spf13/cobra/command.go:958 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
	/drone/src/vendor/github.com/spf13/cobra/command.go:895
github.com/rancher/k3d/v4/cmd.Execute()
	/drone/src/cmd/root.go:91 +0x5a
main.main()
	/drone/src/main.go:27 +0x25

The result of host network is as follows

$ docker network inspect host

[
    {
        "Name": "host",
        "Id": "041f23567f983cf36ceb395d9611844ccc6c55e244ab8c6ea44cabf5ebac01f9",
        "Created": "2020-05-12T14:00:14.11112718Z",
        "Scope": "local",
        "Driver": "host",
        "EnableIPv6": false,
        "IPAM": {
            "Driver": "default",
            "Options": null,
            "Config": []
        },
        "Internal": false,
        "Attachable": false,
        "Ingress": false,
        "ConfigFrom": {
            "Network": ""
        },
        "ConfigOnly": false,
        "Containers": {},
        "Options": {},
        "Labels": {}
    }
]

[iwilltry42]

Hey there 👋
Can you please try with the latest version of k3d as we integrated some changes to handle --network host a bit better.
Additionally, I just pushed some improved error handling for this specific issue in 8b0174b

[catchme1412]

I will wait for the new version. When I try using 4.2.0 version, I get the problem.