Helm installation for vcluster

[yorugac]

Currently vcluster is invoked with a simple os/exec which adds a requirement to have vcluster binary already installed in the system. Since another way to create a virtual cluster is with Helm chart, it'd be good to switch to that and remove dependency on the binary.

After looking into this possibility, it appears that there is a CreateHelm Golang function that can be used directly for creation, for example:

import (
	"context"

	"github.com/loft-sh/log"
	"github.com/loft-sh/vcluster/pkg/cli"
	"github.com/loft-sh/vcluster/pkg/cli/flags"
)

func create(ctx context.Context, name string) error {
	opts := &cli.CreateOptions{
		KubeConfigContextName: name,
	}
	flags := flags.GlobalFlags{
		Context:   "..",
		Namespace: "..",
	}
	log := log.New() // or smth smarter

	return cli.CreateHelm(ctx, opts, flags, name, log)
}

Similarly, DeleteHelm function can be used for deletion.

Caveat: creating namespace might be a requirement with this method. Needs to be checked.

Apparently, under the hood, both of those functions are also relying on os/exec of Helm binary though with added bonus of implemented downloader: likely when Helm installation is absent, vcluster is downloading its binary to /tmp.

These should be sufficient for xk6-environment at this point. However, as of now, these functions are absent in latest stable version so it makes sense to wait a bit for the next release before adding them.