providers/azure: add support for azure gen2 VMs

Fixes coreos#1194
This change uses the same path for gen1 and gen2 VMs because
they can't easily be distinguished at runtime.

internal/providers/azure/azure.go

@@ -21,10 +21,8 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"time"
 
 	"github.com/coreos/ignition/v2/config/v3_4_experimental/types"
-	"github.com/coreos/ignition/v2/internal/distro"
 	execUtil "github.com/coreos/ignition/v2/internal/exec/util"
 	"github.com/coreos/ignition/v2/internal/log"
 	"github.com/coreos/ignition/v2/internal/providers/util"
@@ -35,8 +33,7 @@ import (
 )
 
 const (
-	configDeviceID = "ata-Virtual_CD"
-	configPath     = "/CustomData.bin"
+	configPath = "/CustomData.bin"
 )
 
 // These constants come from <cdrom.h>.
@@ -66,29 +63,43 @@ func FetchConfig(f *resource.Fetcher) (types.Config, report.Report, error) {
 // FetchFromOvfDevice has the return signature of platform.NewFetcher. It is
 // wrapped by this and AzureStack packages.
 func FetchFromOvfDevice(f *resource.Fetcher, ovfFsTypes []string) (types.Config, report.Report, error) {
-	devicePath := filepath.Join(distro.DiskByIDDir(), configDeviceID)
-
+	var rawConfig []byte
 	logger := f.Logger
-	logger.Debug("waiting for config DVD...")
-	waitForCdrom(logger, devicePath)
 
-	fsType, err := checkOvfFsType(logger, devicePath, ovfFsTypes)
-	if err != nil {
-		return types.Config{}, report.Report{}, err
+	for _, ovfFsType := range ovfFsTypes {
+		device, err := execUtil.GetBlockDevices(ovfFsType)
+		if err != nil {
+			return types.Config{}, report.Report{}, fmt.Errorf("failed to retrieve block devices with FSTYPE=UDF: %v", err)
+		} else if len(device) > 0 {
+			for i, dev := range device {
+				rawConfig, err = getRawConfig(f, dev)
+				if len(rawConfig) > 0 && isCdromPresent(logger, dev) {
+					break
+				} else if err != nil && i == len(device) {
+					return types.Config{}, report.Report{}, fmt.Errorf("failed to retrieve config: %v", err)
+				}
+			}
+		}
+
 	}
+	return util.ParseConfig(logger, rawConfig)
+}
 
+// getRawConfig returns the config by mounting the given block device
+func getRawConfig(f *resource.Fetcher, devicePath string) ([]byte, error) {
+	logger := f.Logger
 	mnt, err := ioutil.TempDir("", "ignition-azure")
 	if err != nil {
-		return types.Config{}, report.Report{}, fmt.Errorf("failed to create temp directory: %v", err)
+		return nil, fmt.Errorf("failed to create temp directory: %v", err)
 	}
 	defer os.Remove(mnt)
 
 	logger.Debug("mounting config device")
 	if err := logger.LogOp(
-		func() error { return unix.Mount(devicePath, mnt, fsType, unix.MS_RDONLY, "") },
+		func() error { return unix.Mount(devicePath, mnt, CDS_FSTYPE_UDF, unix.MS_RDONLY, "") },
 		"mounting %q at %q", devicePath, mnt,
 	); err != nil {
-		return types.Config{}, report.Report{}, fmt.Errorf("failed to mount device %q at %q: %v", devicePath, mnt, err)
+		return nil, fmt.Errorf("failed to mount device %q at %q: %v", devicePath, mnt, err)
 	}
 	defer func() {
 		_ = logger.LogOp(
@@ -97,19 +108,18 @@ func FetchFromOvfDevice(f *resource.Fetcher, ovfFsTypes []string) (types.Config,
 		)
 	}()
 
-	logger.Debug("reading config")
-	rawConfig, err := ioutil.ReadFile(filepath.Join(mnt, configPath))
+	logger.Debug("checking for config drive")
+	_, err = ioutil.ReadFile(filepath.Join(mnt, "ovf-env.xml"))
 	if err != nil && !os.IsNotExist(err) {
-		return types.Config{}, report.Report{}, fmt.Errorf("failed to read config: %v", err)
+		return nil, fmt.Errorf("failed to identify config drive: %v", err)
 	}
 
-	return util.ParseConfig(logger, rawConfig)
-}
-
-func waitForCdrom(logger *log.Logger, devicePath string) {
-	for !isCdromPresent(logger, devicePath) {
-		time.Sleep(time.Second)
+	logger.Debug("reading config")
+	rawConfig, err := ioutil.ReadFile(filepath.Join(mnt, configPath))
+	if err != nil && !os.IsNotExist(err) {
+		return nil, fmt.Errorf("failed to read config: %v", err)
 	}
+	return rawConfig, nil
 }
 
 func isCdromPresent(logger *log.Logger, devicePath string) bool {
@@ -146,16 +156,3 @@ func isCdromPresent(logger *log.Logger, devicePath string) bool {
 
 	return (status == CDS_DISC_OK)
 }
-
-func checkOvfFsType(logger *log.Logger, devicePath string, fsTypes []string) (string, error) {
-	fs, err := execUtil.GetFilesystemInfo(devicePath, false)
-	if err != nil {
-		return fs.Type, fmt.Errorf("failed to detect filesystem on ovf device %q: %v", devicePath, err)
-	}
-	for _, f := range fsTypes {
-		if f == fs.Type {
-			return fs.Type, nil
-		}
-	}
-	return fs.Type, fmt.Errorf("filesystem %q is not a supported ovf device", fs.Type)
-}