Add supports for k0s

README.md

@@ -100,6 +100,14 @@ To enable Kubernetes, start Colima with `--kubernetes` flag.
 colima start --kubernetes
 ```
 
+By default, colima use [k3s](https://github.com/k3s-io/k3s/).
+
+Use [k0s](https://github.com/k0sproject/k0s).
+
+```
+colima start --kubernetes --k0s
+```
+
 #### Interacting with Image Registry
 
 For Docker runtime, images built or pulled with Docker are accessible to Kubernetes.

app/app.go

@@ -70,7 +70,11 @@ func (c colimaApp) startWithRuntime(conf config.Config) ([]environment.Container
 	{
 		runtime := conf.Runtime
 		if kubernetesEnabled {
-			runtime += "+k3s"
+			if conf.Kubernetes.UseK0s {
+				runtime += "+k0s"
+			} else {
+				runtime += "+k3s"
+			}
 		}
 		log.Println("runtime:", runtime)
 	}

cmd/start.go

@@ -45,7 +45,9 @@ Run 'colima template' to set the default configurations or 'colima start --edit'
 		"  colima start --arch aarch64\n" +
 		"  colima start --dns 1.1.1.1 --dns 8.8.8.8\n" +
 		"  colima start --dns-host example.com=1.2.3.4\n" +
-		"  colima start --kubernetes --k3s-arg=--disable=coredns,servicelb,traefik,local-storage,metrics-server",
+		"  colima start --kubernetes --k3s-arg=--disable=coredns,servicelb,traefik,local-storage,metrics-server" +
+		"  colima start --kubernetes --k0s" +
+		"  colima start --kubernetes --k0s --kubernetes-version=v1.28.15+k0s.0",
 	Args: cobra.MaximumNArgs(1),
 	RunE: func(cmd *cobra.Command, args []string) error {
 		app := newApp()
@@ -109,10 +111,11 @@ Run 'colima template' to set the default configurations or 'colima start --edit'
 }
 
 const (
-	defaultCPU               = 2
-	defaultMemory            = 2
-	defaultDisk              = 100
-	defaultKubernetesVersion = kubernetes.DefaultVersion
+	defaultCPU        = 2
+	defaultMemory     = 2
+	defaultDisk       = 100
+	defaultK3sVersion = kubernetes.DefaultK3sVersion
+	defaultK0sVersion = kubernetes.DefaultK0sVersion
 
 	defaultMountTypeQEMU = "sshfs"
 	defaultMountTypeVZ   = "virtiofs"
@@ -204,7 +207,8 @@ func init() {
 	// k8s
 	startCmd.Flags().BoolVarP(&startCmdArgs.Kubernetes.Enabled, "kubernetes", "k", false, "start with Kubernetes")
 	startCmd.Flags().BoolVar(&startCmdArgs.Flags.LegacyKubernetes, "with-kubernetes", false, "start with Kubernetes")
-	startCmd.Flags().StringVar(&startCmdArgs.Kubernetes.Version, "kubernetes-version", defaultKubernetesVersion, "must match a k3s version https://github.com/k3s-io/k3s/releases")
+	startCmd.Flags().StringVar(&startCmdArgs.Kubernetes.Version, "kubernetes-version", "", "Kubernetes version to use")
+	startCmd.Flags().BoolVarP(&startCmdArgs.Kubernetes.UseK0s, "k0s", "0", false, "use k0s instead of k3s")
 	startCmd.Flags().StringSliceVar(&startCmdArgs.Flags.LegacyKubernetesDisable, "kubernetes-disable", nil, "components to disable for k3s e.g. traefik,servicelb")
 	startCmd.Flags().StringSliceVar(&startCmdArgs.Kubernetes.K3sArgs, "k3s-arg", defaultK3sArgs, "additional args to pass to k3s")
 	startCmd.Flag("with-kubernetes").Hidden = true
@@ -417,6 +421,9 @@ func prepareConfig(cmd *cobra.Command) {
 	if !cmd.Flag("kubernetes-version").Changed {
 		startCmdArgs.Kubernetes.Version = current.Kubernetes.Version
 	}
+	if !cmd.Flag("k0s").Changed {
+		startCmdArgs.Kubernetes.UseK0s = current.Kubernetes.UseK0s
+	}
 	if !cmd.Flag("k3s-arg").Changed {
 		startCmdArgs.Kubernetes.K3sArgs = current.Kubernetes.K3sArgs
 	}

config/config.go

@@ -70,6 +70,7 @@ type Kubernetes struct {
 	Enabled bool     `yaml:"enabled"`
 	Version string   `yaml:"version"`
 	K3sArgs []string `yaml:"k3sArgs"`
+	UseK0s  bool     `yaml:"usek0s"`
 }
 
 // Network is VM network configuration

environment/container/kubernetes/k0s.go

@@ -0,0 +1,42 @@
+package kubernetes
+
+import (
+	"fmt"
+
+	"github.com/abiosoft/colima/cli"
+	"github.com/abiosoft/colima/environment"
+)
+
+func installK0s(
+	guest environment.GuestActions,
+	a *cli.ActiveCommandChain,
+	k0sVersion string,
+) {
+	installK0sBinary(guest, a, k0sVersion)
+	installK0sCluster(guest, a)
+}
+
+func installK0sBinary(
+	guest environment.GuestActions,
+	a *cli.ActiveCommandChain,
+	k0sVersion string,
+) {
+	a.Add(func() error {
+		k0senv := fmt.Sprintf("K0S_VERSION=%s", k0sVersion)
+		cmd := fmt.Sprintf("curl --tlsv1.2 -sSf https://get.k0s.sh | sudo %s sh", k0senv)
+		if err := guest.Run("sh", "-c", cmd); err != nil {
+			return fmt.Errorf("failed to install k0s %w", err)
+		}
+		return nil
+	})
+}
+
+func installK0sCluster(
+	guest environment.GuestActions,
+	a *cli.ActiveCommandChain,
+) {
+	// Initialize k0s with default configuration
+	a.Add(func() error {
+		return guest.Run("sudo", "k0s", "install", "controller", "--single")
+	})
+}

environment/container/kubernetes/kubeconfig.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 
@@ -46,16 +47,31 @@ func (c kubernetesRuntime) provisionKubeconfig(ctx context.Context) error {
 
 	// manipulate in VM and save to host
 	a.Add(func() error {
-		kubeconfig, err := c.guest.Read("/etc/rancher/k3s/k3s.yaml")
-		if err != nil {
-			return fmt.Errorf("error fetching kubeconfig on guest: %w", err)
-		}
-		// replace name
-		kubeconfig = strings.ReplaceAll(kubeconfig, ": default", ": "+profile)
+		var err error
+		kubeconfig := ""
+		if c.config().UseK0s {
+			kubeconfig, err = c.guest.Read("/var/lib/k0s/pki/admin.conf")
+			if err != nil {
+				return fmt.Errorf("error fetching kubeconfig on guest: %w", err)
+			}
+			kubeconfig = strings.ReplaceAll(kubeconfig, ": Default", ": "+profile)
 
-		// replace IP
-		if ip != "" && ip != "127.0.0.1" {
-			kubeconfig = strings.ReplaceAll(kubeconfig, "https://127.0.0.1:", "https://"+ip+":")
+			if ip != "" && ip != "127.0.0.1" {
+				re := regexp.MustCompile(`https://[^:]+:`)
+				kubeconfig = re.ReplaceAllString(kubeconfig, "https://"+ip+":")
+			}
+		} else {
+			kubeconfig, err = c.guest.Read("/etc/rancher/k3s/k3s.yaml")
+			if err != nil {
+				return fmt.Errorf("error fetching kubeconfig on guest: %w", err)
+			}
+			// replace name
+			kubeconfig = strings.ReplaceAll(kubeconfig, ": default", ": "+profile)
+
+			// replace IP
+			if ip != "" && ip != "127.0.0.1" {
+				kubeconfig = strings.ReplaceAll(kubeconfig, "https://127.0.0.1:", "https://"+ip+":")
+			}
 		}
 
 		// save on the host

environment/container/kubernetes/kubernetes.go

@@ -17,10 +17,10 @@ import (
 // Name is container runtime name
 
 const (
-	Name           = "kubernetes"
-	DefaultVersion = "v1.31.2+k3s1"
-
-	ConfigKey = "kubernetes_config"
+	Name              = "kubernetes"
+	DefaultK3sVersion = "v1.31.2+k3s1"
+	DefaultK0sVersion = "v1.31.3+k0s.0"
+	ConfigKey         = "kubernetes_config"
 )
 
 func newRuntime(host environment.HostActions, guest environment.GuestActions) environment.Container {
@@ -47,21 +47,35 @@ func (c kubernetesRuntime) Name() string {
 	return Name
 }
 
-func (c kubernetesRuntime) isInstalled() bool {
+func (c kubernetesRuntime) isInstalled(useK0s bool) bool {
+	if useK0s {
+		return c.guest.RunQuiet("command", "-v", "k0s") == nil
+	}
 	// it is installed if uninstall script is present.
 	return c.guest.RunQuiet("command", "-v", "k3s-uninstall.sh") == nil
 }
 
-func (c kubernetesRuntime) isVersionInstalled(version string) bool {
-	// validate version change via cli flag/config.
-	out, err := c.guest.RunOutput("k3s", "--version")
-	if err != nil {
-		return false
+func (c kubernetesRuntime) isVersionInstalled(version string, useK0s bool) bool {
+	if useK0s {
+		out, err := c.guest.RunOutput("k0s", "version")
+		if err != nil {
+			return false
+		}
+		return strings.Contains(out, version)
+	} else {
+		// validate version change via cli flag/config.
+		out, err := c.guest.RunOutput("k3s", "--version")
+		if err != nil {
+			return false
+		}
+		return strings.Contains(out, version)
 	}
-	return strings.Contains(out, version)
 }
 
 func (c kubernetesRuntime) Running(context.Context) bool {
+	if c.config().UseK0s {
+		return c.guest.RunQuiet("sudo", "service", "k0scontroller", "status") == nil
+	}
 	return c.guest.RunQuiet("sudo", "service", "k3s", "status") == nil
 }
 
@@ -70,10 +84,20 @@ func (c kubernetesRuntime) runtime() string {
 }
 
 func (c kubernetesRuntime) config() config.Kubernetes {
-	conf := config.Kubernetes{Version: DefaultVersion}
+	conf := config.Kubernetes{}
 	if b := c.guest.Get(ConfigKey); b != "" {
 		_ = json.Unmarshal([]byte(b), &conf)
 	}
+
+	// Set default version based on UseK0s flag
+	if conf.Version == "" {
+		if conf.UseK0s {
+			conf.Version = DefaultK0sVersion
+		} else {
+			conf.Version = DefaultK3sVersion
+		}
+	}
+
 	return conf
 }
 
@@ -104,16 +128,17 @@ func (c *kubernetesRuntime) Provision(ctx context.Context) error {
 		conf = c.config()
 	}
 
-	if c.isVersionInstalled(conf.Version) {
+	if c.isVersionInstalled(conf.Version, conf.UseK0s) {
 		// runtime has changed, ensure the required images are in the registry
 		if currentRuntime := c.runtime(); currentRuntime != "" && currentRuntime != runtime {
-			a.Stagef("changing runtime to %s", runtime)
-			installK3sCache(c.host, c.guest, a, log, runtime, conf.Version)
+			if !conf.UseK0s {
+				a.Stagef("changing runtime to %s", runtime)
+				// other settings may have changed e.g. ingress
+				installK3sCache(c.host, c.guest, a, log, runtime, conf.Version)
+			}
 		}
-		// other settings may have changed e.g. ingress
-		installK3sCluster(c.host, c.guest, a, runtime, conf.Version, conf.K3sArgs)
 	} else {
-		if c.isInstalled() {
+		if c.isInstalled(conf.UseK0s) {
 			a.Stagef("version changed to %s, downloading and installing", conf.Version)
 		} else {
 			if ok {
@@ -122,13 +147,19 @@ func (c *kubernetesRuntime) Provision(ctx context.Context) error {
 				a.Stage("installing")
 			}
 		}
-		installK3s(c.host, c.guest, a, log, runtime, conf.Version, conf.K3sArgs)
+		if conf.UseK0s {
+			installK0s(c.guest, a, conf.Version)
+		} else {
+			installK3s(c.host, c.guest, a, log, runtime, conf.Version, conf.K3sArgs)
+		}
 	}
 
 	// this needs to happen on each startup
 	{
-		// cni is used by both cri-dockerd and containerd
-		installCniConfig(c.guest, a)
+		if !conf.UseK0s {
+			// cni is used by both cri-dockerd and containerd
+			installCniConfig(c.guest, a)
+		}
 	}
 
 	// provision successful, now we can persist the version
@@ -145,12 +176,21 @@ func (c kubernetesRuntime) Start(ctx context.Context) error {
 		return nil
 	}
 
-	a.Add(func() error {
-		return c.guest.Run("sudo", "service", "k3s", "start")
-	})
-	a.Retry("", time.Second*2, 10, func(int) error {
-		return c.guest.RunQuiet("kubectl", "cluster-info")
-	})
+	if c.config().UseK0s {
+		a.Add(func() error {
+			return c.guest.Run("sudo", "systemctl", "start", "k0scontroller")
+		})
+		a.Retry("", time.Second*2, 10, func(int) error {
+			return c.guest.RunQuiet("sudo", "k0s", "kubectl", "cluster-info")
+		})
+	} else {
+		a.Add(func() error {
+			return c.guest.Run("sudo", "service", "k3s", "start")
+		})
+		a.Retry("", time.Second*2, 10, func(int) error {
+			return c.guest.RunQuiet("kubectl", "cluster-info")
+		})
+	}
 
 	if err := a.Exec(); err != nil {
 		return err
@@ -238,15 +278,24 @@ func (c kubernetesRuntime) runningContainerIDs() string {
 func (c kubernetesRuntime) Teardown(ctx context.Context) error {
 	a := c.Init(ctx)
 
-	if c.isInstalled() {
+	if c.isInstalled(c.config().UseK0s) {
 		a.Add(func() error {
-			return c.guest.Run("k3s-uninstall.sh")
+			if c.config().UseK0s {
+				if err := c.guest.Run("sudo", "systemctl", "stop", "k0scontroller"); err != nil {
+					return fmt.Errorf("error stopping k0scontroller services: %w", err)
+				}
+				return c.guest.Run("sudo", "k0s", "reset")
+			} else {
+				return c.guest.Run("k3s-uninstall.sh")
+			}
 		})
 	}
 
-	// k3s is buggy with external containerd for now
-	// cleanup is manual
-	a.Add(c.deleteAllContainers)
+	if !c.config().UseK0s {
+		// k3s is buggy with external containerd for now
+		// cleanup is manual
+		a.Add(c.deleteAllContainers)
+	}
 
 	c.teardownKubeconfig(a)