Merge pull request #19123 from shishir-a412ed/rootfs_size_configurable

daemon option (--storage-opt dm.basesize) for increasing the base device size on daemon restart

daemon/graphdriver/devmapper/deviceset.go

@@ -35,7 +35,7 @@ import (
 var (
 	defaultDataLoopbackSize     int64  = 100 * 1024 * 1024 * 1024
 	defaultMetaDataLoopbackSize int64  = 2 * 1024 * 1024 * 1024
-	defaultBaseFsSize           uint64 = 100 * 1024 * 1024 * 1024
+	defaultBaseFsSize           uint64 = 10 * 1024 * 1024 * 1024
 	defaultThinpBlockSize       uint32 = 128 // 64K = 128 512b sectors
 	defaultUdevSyncOverride            = false
 	maxDeviceID                        = 0xffffff // 24 bit, pool limit
@@ -47,6 +47,7 @@ var (
 	driverDeferredRemovalSupport = false
 	enableDeferredRemoval        = false
 	enableDeferredDeletion       = false
+	userBaseSize                 = false
 )
 
 const deviceSetMetaFile string = "deviceset-metadata"
@@ -1056,6 +1057,80 @@ func (devices *DeviceSet) setupVerifyBaseImageUUIDFS(baseInfo *devInfo) error {
 	return nil
 }
 
+func (devices *DeviceSet) checkGrowBaseDeviceFS(info *devInfo) error {
+
+	if !userBaseSize {
+		return nil
+	}
+
+	if devices.baseFsSize < devices.getBaseDeviceSize() {
+		return fmt.Errorf("devmapper: Base device size cannot be smaller than %s", units.HumanSize(float64(devices.getBaseDeviceSize())))
+	}
+
+	if devices.baseFsSize == devices.getBaseDeviceSize() {
+		return nil
+	}
+
+	info.lock.Lock()
+	defer info.lock.Unlock()
+
+	devices.Lock()
+	defer devices.Unlock()
+
+	info.Size = devices.baseFsSize
+
+	if err := devices.saveMetadata(info); err != nil {
+		// Try to remove unused device
+		delete(devices.Devices, info.Hash)
+		return err
+	}
+
+	return devices.growFS(info)
+}
+
+func (devices *DeviceSet) growFS(info *devInfo) error {
+	if err := devices.activateDeviceIfNeeded(info, false); err != nil {
+		return fmt.Errorf("Error activating devmapper device: %s", err)
+	}
+
+	defer devices.deactivateDevice(info)
+
+	fsMountPoint := "/run/docker/mnt"
+	if _, err := os.Stat(fsMountPoint); os.IsNotExist(err) {
+		if err := os.MkdirAll(fsMountPoint, 0700); err != nil {
+			return err
+		}
+		defer os.RemoveAll(fsMountPoint)
+	}
+
+	options := ""
+	if devices.BaseDeviceFilesystem == "xfs" {
+		// XFS needs nouuid or it can't mount filesystems with the same fs
+		options = joinMountOptions(options, "nouuid")
+	}
+	options = joinMountOptions(options, devices.mountOptions)
+
+	if err := mount.Mount(info.DevName(), fsMountPoint, devices.BaseDeviceFilesystem, options); err != nil {
+		return fmt.Errorf("Error mounting '%s' on '%s': %s", info.DevName(), fsMountPoint, err)
+	}
+
+	defer syscall.Unmount(fsMountPoint, syscall.MNT_DETACH)
+
+	switch devices.BaseDeviceFilesystem {
+	case "ext4":
+		if out, err := exec.Command("resize2fs", info.DevName()).CombinedOutput(); err != nil {
+			return fmt.Errorf("Failed to grow rootfs:%v:%s", err, string(out))
+		}
+	case "xfs":
+		if out, err := exec.Command("xfs_growfs", info.DevName()).CombinedOutput(); err != nil {
+			return fmt.Errorf("Failed to grow rootfs:%v:%s", err, string(out))
+		}
+	default:
+		return fmt.Errorf("Unsupported filesystem type %s", devices.BaseDeviceFilesystem)
+	}
+	return nil
+}
+
 func (devices *DeviceSet) setupBaseImage() error {
 	oldInfo, _ := devices.lookupDeviceWithLock("")
 
@@ -1069,9 +1144,8 @@ func (devices *DeviceSet) setupBaseImage() error {
 				return err
 			}
 
-			if devices.baseFsSize != defaultBaseFsSize && devices.baseFsSize != devices.getBaseDeviceSize() {
+			if err := devices.checkGrowBaseDeviceFS(oldInfo); err != nil {
-				logrus.Warnf("devmapper: Base device is already initialized to size %s, new value of base device size %s will not take effect",
+				return err
-					units.HumanSize(float64(devices.getBaseDeviceSize())), units.HumanSize(float64(devices.baseFsSize)))
 			}
 
 			return nil
@@ -2378,6 +2452,7 @@ func NewDeviceSet(root string, doInit bool, options []string, uidMaps, gidMaps [
 			if err != nil {
 				return nil, err
 			}
+			userBaseSize = true
 			devices.baseFsSize = uint64(size)
 		case "dm.loopdatasize":
 			size, err := units.RAMInBytes(val)

docs/reference/commandline/daemon.md

@@ -213,11 +213,23 @@ options for `zfs` start with `zfs`.
 *  `dm.basesize`
 
     Specifies the size to use when creating the base device, which limits the
-    size of images and containers. The default value is 100G. Note, thin devices
+    size of images and containers. The default value is 10G. Note, thin devices
-    are inherently "sparse", so a 100G device which is mostly empty doesn't use
+    are inherently "sparse", so a 10G device which is mostly empty doesn't use
-    100 GB of space on the pool. However, the filesystem will use more space for
+    10 GB of space on the pool. However, the filesystem will use more space for
     the empty case the larger the device is.
 
+    The base device size can be increased at daemon restart which will allow
+    all future images and containers (based on those new images) to be of the 
+    new base device size.
+
+    Example use: 
+
+        $ docker daemon --storage-opt dm.basesize=50G
+
+    This will increase the base device size to 50G. The Docker daemon will throw an 
+    error if existing base device size is larger than 50G. A user can use 
+    this option to expand the base device size however shrinking is not permitted.
+
     This value affects the system-wide "base" empty filesystem
     that may already be initialized and inherited by pulled images. Typically,
     a change to this value requires additional steps to take effect:

docs/userguide/storagedriver/device-mapper-driver.md

@@ -249,11 +249,11 @@ You can use the `lsblk` command to see the device files created above and the `p
     NAME                       MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
     xvda                       202:0    0    8G  0 disk
     └─xvda1                    202:1    0    8G  0 part /
-    xvdf                       202:80   0  100G  0 disk
+    xvdf                       202:80   0   10G  0 disk
     ├─vg--docker-data          253:0    0   90G  0 lvm
-    │ └─docker-202:1-1032-pool 253:2    0  100G  0 dm
+    │ └─docker-202:1-1032-pool 253:2    0   10G  0 dm
     └─vg--docker-metadata      253:1    0    4G  0 lvm
-      └─docker-202:1-1032-pool 253:2    0  100G  0 dm
+      └─docker-202:1-1032-pool 253:2    0   10G  0 dm
 
 The diagram below shows the image from prior examples updated with the detail from the `lsblk` command above.
 

man/docker-daemon.8.md

@@ -271,12 +271,22 @@ Example use: `docker daemon --storage-opt dm.thinpooldev=/dev/mapper/thin-pool`
 #### dm.basesize
 
 Specifies the size to use when creating the base device, which limits
-the size of images and containers. The default value is 100G. Note,
+the size of images and containers. The default value is 10G. Note,
-thin devices are inherently "sparse", so a 100G device which is mostly
+thin devices are inherently "sparse", so a 10G device which is mostly
-empty doesn't use 100 GB of space on the pool. However, the filesystem
+empty doesn't use 10 GB of space on the pool. However, the filesystem
 will use more space for base images the larger the device
 is.
 
+The base device size can be increased at daemon restart which will allow
+all future images and containers (based on those new images) to be of the 
+new base device size.
+
+Example use: `docker daemon --storage-opt dm.basesize=50G` 
+
+This will increase the base device size to 50G. The Docker daemon will throw an 
+error if existing base device size is larger than 50G. A user can use 
+this option to expand the base device size however shrinking is not permitted.
+
 This value affects the system-wide "base" empty filesystem that may already
 be initialized and inherited by pulled images. Typically, a change to this
 value requires additional steps to take effect: