From 1c79901d6568e59439d6aca263781ea3bc0f48d2 Mon Sep 17 00:00:00 2001
From: Dennis Marttinen <38858901+twelho@users.noreply.github.com>
Date: Thu, 20 Jul 2023 06:31:56 +0000
Subject: [PATCH] Introduce `JUICEFS_IMMUTABLE`, mount `/etc/updatedb.conf`
 only in mutable environments (#680)

* Fix usage of `UpdateDBDirName`

* Introduce `JUICEFS_IMMUTABLE`, mount `/etc/updatedb.conf` only in mutable 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                     |  9 ++++++++
 cmd/node.go                           | 11 +++++++++
 pkg/config/config.go                  |  1 +
 pkg/juicefs/mount/builder/common.go   | 33 ++++++++++++++++++---------
 pkg/juicefs/mount/builder/pod_test.go |  8 +++----
 5 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/cmd/controller.go b/cmd/controller.go
index 83a14747ac..5266a5e185 100644
--- a/cmd/controller.go
+++ b/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")
diff --git a/cmd/node.go b/cmd/node.go
index 51b4c82a9a..88dba85171 100644
--- a/cmd/node.go
+++ b/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")
diff --git a/pkg/config/config.go b/pkg/config/config.go
index 6e193b0471..e9bc845e7c 100644
--- a/pkg/config/config.go
+++ b/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          = ""
diff --git a/pkg/juicefs/mount/builder/common.go b/pkg/juicefs/mount/builder/common.go
index 10eff76e6c..afeffb7d9b 100644
--- a/pkg/juicefs/mount/builder/common.go
+++ b/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: "updatedb",
-		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:             "updatedb",
-		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{
diff --git a/pkg/juicefs/mount/builder/pod_test.go b/pkg/juicefs/mount/builder/pod_test.go
index 0dfad6b30e..40916f4a6a 100644
--- a/pkg/juicefs/mount/builder/pod_test.go
+++ b/pkg/juicefs/mount/builder/pod_test.go
@@ -75,10 +75,10 @@ var (
 						},
 					},
 				}, {
-					Name: "updatedb",
+					Name: UpdateDBDirName,
 					VolumeSource: corev1.VolumeSource{
 						HostPath: &corev1.HostPathVolumeSource{
-							Path: "/etc/updatedb.conf",
+							Path: UpdateDBCfgFile,
 							Type: &file,
 						},
 					},
@@ -106,8 +106,8 @@ var (
 						MountPropagation: &mp,
 					}, {
 
-						Name:             "updatedb",
-						MountPath:        "/etc/updatedb.conf",
+						Name:             UpdateDBDirName,
+						MountPath:        UpdateDBCfgFile,
 						MountPropagation: &mp,
 					},
 				},