Introduce JUICEFS_IMMUTABLE, mount /etc/updatedb.conf only in mut…

…able environments

In immutable environments, such as Talos Linux, most host directories are read-only.
As a result, for example, `FileOrCreate` for the `/etc/updatedb.conf` will fail to
create an empty file. This patch introduces `JUICEFS_IMMUTABLE` as a new environment
variable for both controller and node instances to handle these kinds of cases that
need special attention in immutable environments.

cmd/controller.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"strconv"
 
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/runtime"
@@ -63,6 +64,14 @@ func parseControllerConfig() {
 		config.MountManager = false
 		config.ByProcess = false
 	}
+	if jfsImmutable := os.Getenv("JUICEFS_IMMUTABLE"); jfsImmutable != "" {
+		// check if running in an immutable environment
+		if immutable, err := strconv.ParseBool(jfsImmutable); err == nil {
+			config.Immutable = immutable
+		} else {
+			klog.Errorf("cannot parse JUICEFS_IMMUTABLE: %v", err)
+		}
+	}
 
 	config.NodeName = os.Getenv("NODE_NAME")
 	config.Namespace = os.Getenv("JUICEFS_MOUNT_NAMESPACE")

cmd/node.go

@@ -21,6 +21,7 @@ import (
 	"fmt"
 	"net/http"
 	"os"
+	"strconv"
 	"time"
 
 	"k8s.io/klog"
@@ -42,12 +43,22 @@ func parseNodeConfig() {
 		return
 	}
 	config.FormatInPod = formatInPod
+
+	if jfsImmutable := os.Getenv("JUICEFS_IMMUTABLE"); jfsImmutable != "" {
+		if immutable, err := strconv.ParseBool(jfsImmutable); err == nil {
+			config.Immutable = immutable
+		} else {
+			klog.Errorf("cannot parse JUICEFS_IMMUTABLE: %v", err)
+		}
+	}
+
 	config.NodeName = os.Getenv("NODE_NAME")
 	config.Namespace = os.Getenv("JUICEFS_MOUNT_NAMESPACE")
 	config.PodName = os.Getenv("POD_NAME")
 	config.MountPointPath = os.Getenv("JUICEFS_MOUNT_PATH")
 	config.JFSConfigPath = os.Getenv("JUICEFS_CONFIG_PATH")
 	config.MountLabels = os.Getenv("JUICEFS_MOUNT_LABELS")
+
 	config.HostIp = os.Getenv("HOST_IP")
 	config.KubeletPort = os.Getenv("KUBELET_PORT")
 	jfsMountPriorityName := os.Getenv("JUICEFS_MOUNT_PRIORITY_NAME")

pkg/config/config.go

@@ -31,6 +31,7 @@ var (
 	Provisioner  = false // provisioner in controller
 	MountManager = false // manage mount pod in controller (only in k8s)
 	Webhook      = false // inject juicefs client as sidecar in pod (only in k8s)
+	Immutable    = false // csi driver is running in an immutable environment
 
 	NodeName           = ""
 	Namespace          = ""

pkg/juicefs/mount/builder/common.go

@@ -31,6 +31,7 @@ const (
 	JfsDirName      = "jfs-dir"
 	JfsRootDirName  = "jfs-root-dir"
 	UpdateDBDirName = "updatedb"
+	UpdateDBCfgFile = "/etc/updatedb.conf"
 )
 
 type Builder struct {
@@ -92,15 +93,20 @@ func (r *Builder) getVolumes() []corev1.Volume {
 				Path: config.MountPointPath,
 				Type: &dir,
 			},
-		}}, {
-		Name: UpdateDBDirName,
-		VolumeSource: corev1.VolumeSource{
-			HostPath: &corev1.HostPathVolumeSource{
-				Path: "/etc/updatedb.conf",
-				Type: &file,
-			},
 		},
 	}}
+
+	if !config.Immutable {
+		volumes = append(volumes, corev1.Volume{
+			Name: UpdateDBDirName,
+			VolumeSource: corev1.VolumeSource{
+				HostPath: &corev1.HostPathVolumeSource{
+					Path: UpdateDBCfgFile,
+					Type: &file,
+				},
+			}})
+	}
+
 	if r.jfsSetting.FormatCmd != "" {
 		// initContainer will generate xx.conf to share with mount container
 		volumes = append(volumes, corev1.Volume{
@@ -157,11 +163,16 @@ func (r *Builder) getVolumeMounts() []corev1.VolumeMount {
 		Name:             JfsDirName,
 		MountPath:        config.PodMountBase,
 		MountPropagation: &mp,
-	}, {
-		Name:             UpdateDBDirName,
-		MountPath:        "/etc/updatedb.conf",
-		MountPropagation: &mp,
 	}}
+
+	if !config.Immutable {
+		volumeMounts = append(volumeMounts, corev1.VolumeMount{
+			Name:             UpdateDBDirName,
+			MountPath:        UpdateDBCfgFile,
+			MountPropagation: &mp,
+		})
+	}
+
 	if r.jfsSetting.FormatCmd != "" {
 		// initContainer will generate xx.conf to share with mount container
 		volumeMounts = append(volumeMounts, corev1.VolumeMount{

pkg/juicefs/mount/builder/pod_test.go

@@ -78,7 +78,7 @@ var (
 					Name: UpdateDBDirName,
 					VolumeSource: corev1.VolumeSource{
 						HostPath: &corev1.HostPathVolumeSource{
-							Path: "/etc/updatedb.conf",
+							Path: UpdateDBCfgFile,
 							Type: &file,
 						},
 					},
@@ -107,7 +107,7 @@ var (
 					}, {
 
 						Name:             UpdateDBDirName,
-						MountPath:        "/etc/updatedb.conf",
+						MountPath:        UpdateDBCfgFile,
 						MountPropagation: &mp,
 					},
 				},