[BUG] Unable to run a cluster that mounts existing docker volumes on windows

[dhenneke]

What did you do

1. Create a docker volume docker volume create my-docker-volume

2. Create a new config file:

apiVersion: k3d.io/v1alpha2
kind: Simple
name: test
servers: 1
agents: 0
volumes:
  - volume: my-docker-volume:/var/lib/rancher/k3s/storage
    nodeFilters:
      - all

3. Run k3d cluster create -c config.yaml

What did you expect to happen

The cluster boots. But it crashes with the following error:

INFO[0000] Using config file config.yaml
panic: runtime error: index out of range [2] with length 2

goroutine 1 [running]:
github.com/rancher/k3d/v4/pkg/runtimes/util.ValidateVolumeMount(0x1a373b0, 0x1f21da8, 0xc0004310e0, 0x2d, 0x0, 0x0)
        /drone/src/pkg/runtimes/util/volumes.go:66 +0x4d2
github.com/rancher/k3d/v4/pkg/config.ValidateClusterConfig(0x1a27898, 0xc000036050, 0x1a373b0, 0x1f21da8, 0x0, 0x0, 0x0, 0x0, 0xc000405790, 0x4, ...)
        /drone/src/pkg/config/validate.go:93 +0x17e
github.com/rancher/k3d/v4/cmd/cluster.NewCmdClusterCreate.func2(0xc0003c6000, 0xc00037f5e0, 0x0, 0x2)
        /drone/src/cmd/cluster/clusterCreate.go:159 +0x7b9
github.com/spf13/cobra.(*Command).execute(0xc0003c6000, 0xc00037f5c0, 0x2, 0x2, 0xc0003c6000, 0xc00037f5c0)
        /drone/src/vendor/github.com/spf13/cobra/command.go:856 +0x2c2
github.com/spf13/cobra.(*Command).ExecuteC(0x1ecfda0, 0xc000138010, 0x4, 0x7)
        /drone/src/vendor/github.com/spf13/cobra/command.go:960 +0x375
github.com/spf13/cobra.(*Command).Execute(...)
        /drone/src/vendor/github.com/spf13/cobra/command.go:897
github.com/rancher/k3d/v4/cmd.Execute()
        /drone/src/cmd/root.go:95 +0x65
main.main()
        /drone/src/main.go:27 +0x27

#510 added a workaround to allow c:\folder:/mnt/test mounts, however this breaks volume-mounts like docker-volume:/mnt/test.
https://github.com/rancher/k3d/blob/fd793fe4cba780471c69daeac1ae8234332478d1/cmd/util/volumes.go#L67-L70

An option could be to add an additional check that makes sure that there are enough array elements:

- } else if rt.GOOS == "windows" {
+ } else if rt.GOOS == "windows" && len(split) == 3 {
    src = split[0] + ":" + split[1]
    dest = split[2]
  } ...

Which OS & Architecture

• Windows

Which version of k3d

C:\WINDOWS\system32>k3d --version
k3d version v4.4.2
k3s version v1.20.6-k3s1 (default)

[iwilltry42]

Hi @dhenneke , thanks for pointing this out!
Fix will be included in the next release 👍