k3s: keep the listen port with the runtime disk

environment/container/kubernetes/k3s.go

@@ -12,6 +12,7 @@ import (
 	"github.com/abiosoft/colima/environment/container/containerd"
 	"github.com/abiosoft/colima/environment/container/docker"
 	"github.com/abiosoft/colima/environment/vm/lima/limautil"
+	"github.com/abiosoft/colima/store"
 	"github.com/abiosoft/colima/util"
 	"github.com/abiosoft/colima/util/downloader"
 	"github.com/sirupsen/logrus"
@@ -204,6 +205,7 @@ func installK3sCluster(
 func getPortNumber(guest environment.GuestActions, k3sListenPort int) (int, error) {
 	// port previously set, reuse it
 	if port, err := strconv.Atoi(guest.Get(listenPortKey)); err == nil && port > 0 {
+		saveDiskPortNumber(port)
 		return port, nil
 	}
 
@@ -214,7 +216,10 @@ func getPortNumber(guest environment.GuestActions, k3sListenPort int) (int, erro
 	}
 
 	var port int
-	if k3sListenPort > 0 {
+	if p := diskPortNumber(); p > 0 {
+		// the VM was recreated on a kept runtime disk, whose k3s state still uses this port
+		port = p
+	} else if k3sListenPort > 0 {
 		// template configured port
 		port = k3sListenPort
 	} else {
@@ -225,6 +230,22 @@ func getPortNumber(guest environment.GuestActions, k3sListenPort int) (int, erro
 	if err := guest.Set(listenPortKey, strconv.Itoa(port)); err != nil {
 		return 0, err
 	}
+	saveDiskPortNumber(port)
 
 	return port, nil
 }
+
+// diskPortNumber returns the port k3s used on the runtime disk, if any.
+func diskPortNumber() int {
+	s, _ := store.Load()
+	if !s.DiskFormatted {
+		return 0
+	}
+	return s.K3sListenPort
+}
+
+func saveDiskPortNumber(port int) {
+	if err := store.Set(func(s *store.Store) { s.K3sListenPort = port }); err != nil {
+		logrus.Traceln(fmt.Errorf("error persisting k3s port: %w", err))
+	}
+}

environment/container/kubernetes/k3s_test.go

@@ -0,0 +1,98 @@
+package kubernetes
+
+import (
+	"os"
+	"strconv"
+	"strings"
+	"testing"
+
+	"github.com/abiosoft/colima/config"
+	"github.com/abiosoft/colima/environment"
+	"github.com/abiosoft/colima/store"
+)
+
+func TestMain(m *testing.M) {
+	// config dirs are cached on first use, so point them at a temp dir before any test runs
+	home, err := os.MkdirTemp("", "colima-test")
+	if err != nil {
+		panic(err)
+	}
+	_ = os.Setenv("COLIMA_HOME", home)
+	_ = os.Unsetenv("LIMA_HOME")
+	code := m.Run()
+	_ = os.RemoveAll(home)
+	os.Exit(code)
+}
+
+type fakeGuest struct {
+	environment.GuestActions
+	conf map[string]string
+}
+
+func (f fakeGuest) Get(key string) string { return f.conf[key] }
+
+func (f fakeGuest) Set(key, value string) error {
+	f.conf[key] = value
+	return nil
+}
+
+func Test_getPortNumber(t *testing.T) {
+	config.SetProfile("k3s-port-test")
+	if file := config.CurrentProfile().StoreFile(); !strings.HasPrefix(file, os.Getenv("COLIMA_HOME")) {
+		t.Fatalf("store file %s is outside COLIMA_HOME", file)
+	}
+
+	tests := []struct {
+		name       string
+		store      store.Store
+		guestPort  string
+		configured int
+		want       int
+	}{
+		{
+			name:  "recreated VM on a kept disk reuses the disk port",
+			store: store.Store{DiskFormatted: true, K3sListenPort: 51234},
+			want:  51234,
+		},
+		{
+			name:      "port in the VM is kept for the disk",
+			store:     store.Store{DiskFormatted: true},
+			guestPort: "52345",
+			want:      52345,
+		},
+		{
+			name:       "stored port is ignored without a formatted disk",
+			store:      store.Store{K3sListenPort: 51234},
+			configured: 6443,
+			want:       6443,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if err := store.Set(func(s *store.Store) { *s = tt.store }); err != nil {
+				t.Fatal(err)
+			}
+			t.Cleanup(func() { _ = store.Reset() })
+
+			guest := fakeGuest{conf: map[string]string{}}
+			if tt.guestPort != "" {
+				guest.conf[listenPortKey] = tt.guestPort
+			}
+
+			got, err := getPortNumber(guest, tt.configured)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got != tt.want {
+				t.Errorf("getPortNumber() = %d, want %d", got, tt.want)
+			}
+			if guest.conf[listenPortKey] != strconv.Itoa(tt.want) {
+				t.Errorf("VM port = %s, want %d", guest.conf[listenPortKey], tt.want)
+			}
+			if s, _ := store.Load(); s.K3sListenPort != tt.want {
+				t.Errorf("stored port = %d, want %d", s.K3sListenPort, tt.want)
+			}
+		})
+	}
+}

store/store.go

@@ -17,6 +17,8 @@ type Store struct {
 	DiskRuntime string `json:"disk_runtime"`
 	// if ramalama has been provisioned in the VM
 	RamalamaProvisioned bool `json:"ramalama_provisioned"`
+	// the k3s listen port, kept with the runtime disk that holds the k3s state
+	K3sListenPort int `json:"k3s_listen_port,omitempty"`
 }
 
 func storeFile() string { return config.CurrentProfile().StoreFile() }