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openstack: fetch volume path from metadata service

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The OpenStack cloud provider retrieves mounted Cinder volume paths
by looking in /dev/disk/by-id, expecting the disk serial IDs (e.g.
SCSI ID) to include the volume ID.

The issue is that not all hypervisors are able to expose this.
For example, Hyper-V will just preserve the original Cinder volume
lun SCSI ID (without setting the volume id). For this reason,
disk path lookups will fail.

In order to be able to leverage Hyper-V based OpenStack providers,
as a fallback, we're querying the metadata service, searching for
disk device metadata. Note that starting with Nova Queens, the Hyper-V
driver always provides disk address information through the instance
metadata.
This commit is contained in:
Lucian Petrut
2017-11-06 16:14:28 +02:00
parent 35e9784196
commit 559f83a93d
4 changed files with 139 additions and 18 deletions
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48
pkg/cloudprovider/providers/openstack/metadata.go
View File

@@ -33,11 +33,12 @@ import (
)
const (
// metadataUrl is URL to OpenStack metadata server. It's hardcoded IPv4
// link-local address as documented in "OpenStack Cloud Administrator Guide",
// chapter Compute - Networking with nova-network.
// metadataUrlTemplate allows building an OpenStack Metadata service URL.
// It's a hardcoded IPv4 link-local address as documented in "OpenStack Cloud
// Administrator Guide", chapter Compute - Networking with nova-network.
// https://docs.openstack.org/admin-guide/compute-networking-nova.html#metadata-service
metadataUrl = "http://169.254.169.254/openstack/2012-08-10/meta_data.json"
defaultMetadataVersion = "2012-08-10"
metadataUrlTemplate = "http://169.254.169.254/openstack/%s/meta_data.json"
// metadataID is used as an identifier on the metadata search order configuration.
metadataID = "metadataService"
@@ -45,8 +46,8 @@ const (
// Config drive is defined as an iso9660 or vfat (deprecated) drive
// with the "config-2" label.
// http://docs.openstack.org/user-guide/cli-config-drive.html
configDriveLabel = "config-2"
configDrivePath = "openstack/2012-08-10/meta_data.json"
configDriveLabel = "config-2"
configDrivePathTemplate = "openstack/%s/meta_data.json"
// configDriveID is used as an identifier on the metadata search order configuration.
configDriveID = "configDrive"
@@ -54,12 +55,23 @@ const (
var ErrBadMetadata = errors.New("invalid OpenStack metadata, got empty uuid")
// There are multiple device types. To keep it simple, we're using a single structure
// for all device metadata types.
type DeviceMetadata struct {
Type string `json:"type"`
Bus string `json:"bus,omitempty"`
Serial string `json:"serial,omitempty"`
Address string `json:"address,omitempty"`
// .. and other fields.
}
// Assumes the "2012-08-10" meta_data.json format.
// See http://docs.openstack.org/user-guide/cli_config_drive.html
type Metadata struct {
Uuid string `json:"uuid"`
Name string `json:"name"`
AvailabilityZone string `json:"availability_zone"`
Uuid string `json:"uuid"`
Name string `json:"name"`
AvailabilityZone string `json:"availability_zone"`
Devices []DeviceMetadata `json:"devices,omitempty"`
// .. and other fields we don't care about. Expand as necessary.
}
@@ -79,7 +91,15 @@ func parseMetadata(r io.Reader) (*Metadata, error) {
return &metadata, nil
}
func getMetadataFromConfigDrive() (*Metadata, error) {
func getMetadataUrl(metadataVersion string) string {
return fmt.Sprintf(metadataUrlTemplate, metadataVersion)
}
func getConfigDrivePath(metadataVersion string) string {
return fmt.Sprintf(configDrivePathTemplate, metadataVersion)
}
func getMetadataFromConfigDrive(metadataVersion string) (*Metadata, error) {
// Try to read instance UUID from config drive.
dev := "/dev/disk/by-label/" + configDriveLabel
if _, err := os.Stat(dev); os.IsNotExist(err) {
@@ -114,6 +134,7 @@ func getMetadataFromConfigDrive() (*Metadata, error) {
glog.V(4).Infof("Configdrive mounted on %s", mntdir)
configDrivePath := getConfigDrivePath(metadataVersion)
f, err := os.Open(
filepath.Join(mntdir, configDrivePath))
if err != nil {
@@ -124,8 +145,9 @@ func getMetadataFromConfigDrive() (*Metadata, error) {
return parseMetadata(f)
}
func getMetadataFromMetadataService() (*Metadata, error) {
func getMetadataFromMetadataService(metadataVersion string) (*Metadata, error) {
// Try to get JSON from metadata server.
metadataUrl := getMetadataUrl(metadataVersion)
glog.V(4).Infof("Attempting to fetch metadata from %s", metadataUrl)
resp, err := http.Get(metadataUrl)
if err != nil {
@@ -154,9 +176,9 @@ func getMetadata(order string) (*Metadata, error) {
id = strings.TrimSpace(id)
switch id {
case configDriveID:
md, err = getMetadataFromConfigDrive()
md, err = getMetadataFromConfigDrive(defaultMetadataVersion)
case metadataID:
md, err = getMetadataFromMetadataService()
md, err = getMetadataFromMetadataService(defaultMetadataVersion)
default:
err = fmt.Errorf("%s is not a valid metadata search order option. Supported options are %s and %s", id, configDriveID, metadataID)
}