feat: read metadata from envvars with fallback

driver/helper/metadata.go

@@ -14,6 +14,29 @@ type deviceInfo struct {
 }
 
 func getDeviceInfo(metadataFile string) (*deviceInfo, error) {
+	// reading device info from envvars is the new approach,
+	// so try to use it and fallback if no envvar is defined
+	deviceInfo := getDeviceInfoFromEnv()
+	if deviceInfo.Metadata.LocalVMID == "" {
+		return getDeviceInfoFromFile(metadataFile)
+	}
+	return deviceInfo, nil
+}
+
+func getDeviceInfoFromEnv() *deviceInfo {
+	cloudID := os.Getenv("XELON_CLOUD_ID")
+	localVMID := os.Getenv("XELON_LOCAL_VM_ID")
+	hostname := os.Getenv("XELON_VM_HOSTNAME")
+
+	deviceInfoFromEnv := new(deviceInfo)
+	deviceInfoFromEnv.Metadata.CloudID = cloudID
+	deviceInfoFromEnv.Metadata.LocalVMID = localVMID
+	deviceInfoFromEnv.Metadata.Hostname = hostname
+
+	return deviceInfoFromEnv
+}
+
+func getDeviceInfoFromFile(metadataFile string) (*deviceInfo, error) {
 	f, err := os.Open(metadataFile)
 	if err != nil {
 		return nil, err

driver/helper/metadata_test.go

@@ -0,0 +1,61 @@
+package helper
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetDeviceInfoFromEnv(t *testing.T) {
+	setUpEnvVars()
+	_ = os.Setenv("XELON_CLOUD_ID", "5")
+	_ = os.Setenv("XELON_LOCAL_VM_ID", "abcd1234")
+	_ = os.Setenv("XELON_VM_HOSTNAME", "test.local")
+
+	deviceInfo := getDeviceInfoFromEnv()
+
+	assert.Equal(t, "5", deviceInfo.Metadata.CloudID)
+	assert.Equal(t, "abcd1234", deviceInfo.Metadata.LocalVMID)
+	assert.Equal(t, "test.local", deviceInfo.Metadata.Hostname)
+}
+
+func TestGetDeviceInfoFromFile_valid(t *testing.T) {
+	setUpEnvVars()
+	metadataFile := filepath.Join("testdata", "valid-metadata.json")
+
+	deviceInfo, err := getDeviceInfoFromFile(metadataFile)
+
+	assert.NoError(t, err)
+	assert.Equal(t, "1", deviceInfo.Metadata.CloudID)
+	assert.Equal(t, "abcd1234", deviceInfo.Metadata.LocalVMID)
+	assert.Equal(t, "test.local", deviceInfo.Metadata.Hostname)
+}
+
+func TestGetDeviceInfoFromFile_invalid(t *testing.T) {
+	setUpEnvVars()
+	metadataFile := filepath.Join("testdata", "invalid-metadata.json")
+
+	_, err := getDeviceInfoFromFile(metadataFile)
+
+	assert.Error(t, err)
+}
+
+func TestGetDeviceInfo(t *testing.T) {
+	setUpEnvVars()
+	// XELON_LOCAL_VM_ID is not defined, fallback to file values
+	_ = os.Setenv("XELON_CLOUD_ID", "5")
+	metadataFile := filepath.Join("testdata", "valid-metadata.json")
+
+	deviceInfo, err := getDeviceInfo(metadataFile)
+
+	assert.NoError(t, err)
+	assert.Equal(t, "1", deviceInfo.Metadata.CloudID)
+}
+
+func setUpEnvVars() {
+	_ = os.Unsetenv("XELON_CLOUD_ID")
+	_ = os.Unsetenv("XELON_LOCAL_VM_ID")
+	_ = os.Unsetenv("XELON_VM_HOSTNAME")
+}

driver/helper/testdata/invalid-metadata.json

@@ -0,0 +1,2 @@
+{
+	"invalid-json-format": "some-value"

driver/helper/testdata/valid-metadata.json

@@ -0,0 +1,7 @@
+{
+	"metadata": {
+		"cloudId": "1",
+		"local_id": "abcd1234",
+		"hostname": "test.local"
+	}
+}