minikube: none driver can't be used with non-Docker runtimes (looks for "docker" executable)

There is something wrong in the runtime detection of the precreate:

$ sudo minikube start --vm-driver=none --container-runtime=cri-o
😄  minikube v1.4.0 on Ubuntu 16.04
🤹  Running on localhost (CPUs=4, Memory=7800MB, Disk=138379MB) ...
🔄  Retriable failure: create: precreate: exec: "docker": executable file not found in $PATH
🤹  Running on localhost (CPUs=4, Memory=7800MB, Disk=138379MB) ...
🔄  Retriable failure: create: precreate: exec: "docker": executable file not found in $PATH
🤹  Running on localhost (CPUs=4, Memory=7800MB, Disk=138379MB) ...
🔄  Retriable failure: create: precreate: exec: "docker": executable file not found in $PATH
^C

For some reason it is calling the wrong Available function ?

func (r *Docker) Available() error {
	_, err := exec.LookPath("docker")
	return err
}

func (r *CRIO) Available() error {
	return r.Runner.Run("command -v crio")
}

And the docker runtime seems to be checking locally ? (I guess us using docker machine makes it always there)

It also forgot to look for crictl, but that is another story. (and interesting how this is regarded as a “retriable failure”)

About this issue

Original URL
State: open
Created 5 years ago
Reactions: 1
Comments: 15 (2 by maintainers)

Most upvoted comments

This issue has to do with how the none driver is designed, relative to how createHost[pkg/minikube/machine/start.go] is designed:


func createHost(api libmachine.API, cfg *config.ClusterConfig, n *config.Node) (*host.Host, error) {
       // inside this function we have access to the cluster config.
       // ....
	def := registry.Driver(cfg.Driver)
       // ....
	dd, err := def.Config(*cfg, *n)
       // ....
	data, err := json.Marshal(dd)
       // ....

	h, err := api.NewHost(cfg.Driver, data)
       // ...
	if err := timedCreateHost(h, api, cfg.StartHostTimeout); err != nil {
      // .....

timedCreateHost() in turn, calls api.Create, passing the *host.Host, which contains the driver we’ve *initialized" inside api.NewHost.

The thing is that NewHost (which doesn’t have access to the cluster config) does this annoying thing:

	1. def := registry.Driver(drvName)
	2. d := def.Init()
	3. err := json.Unmarshal(rawDriver, d)
	   where rawDriver is the local name for the passed 'data'

After the json.Unmarshal, that’s the driver we’re ending with.

That’s how the none driver looks like:

type Driver struct {
	*drivers.BaseDriver
	*pkgdrivers.CommonDriver
	URL     string
	runtime cruntime.Manager
	exec    command.Runner
}

it relies on runtime and exec, which have to be initialized, but nothing that is to be initialized would pass the marshal/unmarshal thing in api.NewHost.

So what is happening is that when def.Init() is called inside api.NewHost:

// pkg/minikube/registry/drvs/none/none.go
		Init:     func() drivers.Driver { return none.NewDriver(none.Config{}) },

a none.NewDriver call is issued, with an empty none.Config…

func NewDriver(c Config) *Driver {
	runtime, err := cruntime.New(cruntime.Config{Type: c.ContainerRuntime, Runner: runner})
        // ...
	return &Driver{
               // ...
		runtime: runtime,
	}
}

(makes sense, 'cause we shouldn’t know anything about the driver during initialization… that’s what config should be for)

So that we’re initializing a cruntime with ac.ContainerRuntime == “”, which defaults to docker: case "", "docker":, inside pkg/minikube/cruntime/cruntime.go So no container-runtime config should work with the none driver during this step.

And after our unmarshal… (raw json looking like this:

"{\"IPAddress\":\"\",\"MachineName\":\"minikube\",\"SSHUser\":\"\",\"SSHPort\":0,\"SSHKeyPath\":\"\",\"StorePath\":\"/home/ubuntu/.minikube\",\"SwarmMaster\":false,\"SwarmHost\":\"\",\"SwarmDiscovery\":\"\",\"URL\":\"\"}"

…the runtime field of the struct is not even exported, so there is no way even for the runtime config to be passed on.)

the runtime remains docker.

x7upLime on Jan 29, 2023