feat(init): mount partitions dynamically (#169)

src/image/src/entrypoint.sh

@@ -108,7 +108,7 @@ DEFAULT Dianemo
 LABEL Dianemo
   KERNEL /boot/vmlinuz
   INITRD /boot/initramfs.xz
-  APPEND ${KERNEL_SELF_PROTECTION_PROJECT_KERNEL_PARAMS} ip=dhcp consoleblank=0 console=tty0 console=ttyS0,9600 dianemo.autonomy.io/root=${DIANEMO_ROOT} dianemo.autonomy.io/userdata=${DIANEMO_USERDATA} dianemo.autonomy.io/platform=${DIANEMO_PLATFORM}
+  APPEND ${KERNEL_SELF_PROTECTION_PROJECT_KERNEL_PARAMS} ip=dhcp consoleblank=0 console=tty0 console=ttyS0,9600 dianemo.autonomy.io/userdata=${DIANEMO_USERDATA} dianemo.autonomy.io/platform=${DIANEMO_PLATFORM}
 EOF
 }
 
@@ -120,7 +120,6 @@ function cleanup {
 
 # Defaults
 
-DIANEMO_ROOT="sda"
 DIANEMO_USERDATA=""
 DIANEMO_PLATFORM="bare-metal"
 RAW_IMAGE="/out/image.raw"
@@ -136,7 +135,7 @@ KERNEL_SELF_PROTECTION_PROJECT_KERNEL_PARAMS="page_poison=1 slab_nomerge pti=on"
 case "$1" in
   image)
     shift
-    while getopts "b:flt:p:u:" opt; do
+    while getopts "b:flp:u:" opt; do
       case ${opt} in
         b )
           DEVICE=${OPTARG}
@@ -157,10 +156,6 @@ case "$1" in
           DIANEMO_PLATFORM=${OPTARG}
           echo "Using kernel parameter dianemo.autonomy.io/platform=${DIANEMO_PLATFORM}"
           ;;
-        t )
-          DIANEMO_ROOT=${OPTARG}
-          echo "Using kernel parameter dianemo.autonomy.io/root=${DIANEMO_ROOT}"
-          ;;
         u )
           DIANEMO_USERDATA=${OPTARG}
           echo "Using kernel parameter dianemo.autonomy.io/userdata=${DIANEMO_USERDATA}"

src/image/src/packer.json

@@ -64,7 +64,7 @@
                 "sudo add-apt-repository \"deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable\"",
                 "sudo apt-get -y update",
                 "sudo apt-get -y install docker-ce",
-                "sudo docker run --privileged --volume /dev:/dev autonomy/dianemo:{{ user `version` }} image -b /dev/xvdf -t /dev/xvda -f -p aws -u none"
+                "sudo docker run --privileged --volume /dev:/dev autonomy/dianemo:{{ user `version` }} image -b /dev/xvdf -f -p aws -u none"
             ]
         }
     ]

src/initramfs/cmd/init/pkg/constants/constants.go

@@ -1,10 +1,6 @@
 package constants
 
 const (
-	// KernelParamRoot is the kernel parameter name for specifying the root
-	// disk.
-	KernelParamRoot = "dianemo.autonomy.io/root"
-
 	// KernelParamUserData is the kernel parameter name for specifying the URL
 	// to the user data.
 	KernelParamUserData = "dianemo.autonomy.io/userdata"

src/initramfs/cmd/init/pkg/mount/blkid/blkid.go

@@ -16,6 +16,38 @@ import (
 	"unsafe"
 )
 
+// GetDevWithAttribute returns the dev name of a block device matching the ATTRIBUTE=VALUE
+// pair. Supported attributes are:
+//    TYPE: filesystem type
+//    UUID: filesystem uuid
+//    LABEL: filesystem label
+func GetDevWithAttribute(attribute, value string) (string, error) {
+	var cache C.blkid_cache
+
+	ret := C.blkid_get_cache(&cache, nil)
+	if ret != 0 {
+		return "", fmt.Errorf("failed to get blkid cache: %d", ret)
+	}
+
+	C.blkid_probe_all(cache)
+
+	cs_attribute := C.CString(attribute)
+	cs_value := C.CString(value)
+	defer C.free(unsafe.Pointer(cs_attribute))
+	defer C.free(unsafe.Pointer(cs_value))
+
+	devname := C.blkid_get_devname(cache, cs_attribute, cs_value)
+	defer C.free(unsafe.Pointer(devname))
+
+	// If you have called blkid_get_cache(), you should call blkid_put_cache()
+	// when you are done using the blkid library functions.  This will save the
+	// cache to the blkid.tab file, if you have write access to the file.  It
+	// will also free all associated devices and tags:
+	C.blkid_put_cache(cache)
+
+	return C.GoString(devname), nil
+}
+
 // NewProbeFromFilename executes lblkid blkid_new_probe_from_filename.
 func NewProbeFromFilename(s string) (C.blkid_probe, error) {
 	cs := C.CString(s)

src/initramfs/cmd/init/pkg/mount/mount.go

@@ -9,7 +9,6 @@ import (
 	"sync"
 
 	"github.com/autonomy/dianemo/src/initramfs/cmd/init/pkg/constants"
-	"github.com/autonomy/dianemo/src/initramfs/cmd/init/pkg/kernel"
 	"github.com/autonomy/dianemo/src/initramfs/cmd/init/pkg/mount/blkid"
 	"golang.org/x/sys/unix"
 )
@@ -206,54 +205,56 @@ func mountBlockDevices(s string) (err error) {
 func probe() (b []*BlockDevice, err error) {
 	b = []*BlockDevice{}
 
-	arguments, err := kernel.ParseProcCmdline()
-	if err != nil {
-		return
+	if err := appendBlockDeviceWithLabel(&b, constants.RootPartitionLabel); err != nil {
+		return nil, err
+	}
+	if err := appendBlockDeviceWithLabel(&b, constants.DataPartitionLabel); err != nil {
+		return nil, err
 	}
 
-	if root, ok := arguments[constants.KernelParamRoot]; ok {
-		if _, err := os.Stat(root); os.IsNotExist(err) {
-			return nil, fmt.Errorf("device does not exist: %s", root)
-		}
-		pr, err := blkid.NewProbeFromFilename(root)
-		defer blkid.FreeProbe(pr)
-		if err != nil {
-			return nil, fmt.Errorf("failed to probe %s: %s", root, err)
-		}
+	return b, nil
+}
 
-		ls := blkid.ProbeGetPartitions(pr)
-		nparts := blkid.ProbeGetPartitionsPartlistNumOfPartitions(ls)
+func appendBlockDeviceWithLabel(b *[]*BlockDevice, value string) error {
+	devname, err := blkid.GetDevWithAttribute("LABEL", value)
+	if err != nil {
+		return err
+	}
 
-		for i := 0; i < nparts; i++ {
-			dev := fmt.Sprintf("%s%d", root, i+1)
-			pr, err = blkid.NewProbeFromFilename(dev)
-			defer blkid.FreeProbe(pr)
-			if err != nil {
-				return nil, fmt.Errorf("failed to probe %s: %s", dev, err)
-			}
+	blockDevice, err := probeDevice(devname)
+	if err != nil {
+		return err
+	}
 
-			blkid.DoProbe(pr)
-			UUID, err := blkid.ProbeLookupValue(pr, "UUID", nil)
-			if err != nil {
-				return nil, err
-			}
-			TYPE, err := blkid.ProbeLookupValue(pr, "TYPE", nil)
-			if err != nil {
-				return nil, err
-			}
-			LABEL, err := blkid.ProbeLookupValue(pr, "LABEL", nil)
-			if err != nil {
-				return nil, err
-			}
+	*b = append(*b, blockDevice)
 
-			b = append(b, &BlockDevice{
-				dev:   dev,
-				UUID:  UUID,
-				TYPE:  TYPE,
-				LABEL: LABEL,
-			})
-		}
+	return nil
+}
+
+func probeDevice(devname string) (*BlockDevice, error) {
+	pr, err := blkid.NewProbeFromFilename(devname)
+	defer blkid.FreeProbe(pr)
+	if err != nil {
+		return nil, fmt.Errorf("failed to probe %s: %s", devname, err)
+	}
+	blkid.DoProbe(pr)
+	UUID, err := blkid.ProbeLookupValue(pr, "UUID", nil)
+	if err != nil {
+		return nil, err
+	}
+	TYPE, err := blkid.ProbeLookupValue(pr, "TYPE", nil)
+	if err != nil {
+		return nil, err
+	}
+	LABEL, err := blkid.ProbeLookupValue(pr, "LABEL", nil)
+	if err != nil {
+		return nil, err
 	}
 
-	return b, nil
+	return &BlockDevice{
+		dev:   devname,
+		UUID:  UUID,
+		TYPE:  TYPE,
+		LABEL: LABEL,
+	}, nil
 }