fix: on demand plant id generation (#21873)

util/machine/machine.go

@@ -8,10 +8,15 @@ import (
 	"strings"
 
 	"github.com/denisbrodbeck/machineid"
+	"github.com/evcc-io/evcc/core/keys"
+	"github.com/evcc-io/evcc/server/db/settings"
 	"github.com/samber/lo"
 )
 
-var id string
+var (
+	id           string
+	getMachineID = machineid.ID
+)
 
 // CustomID sets the machine id to a custom value
 func CustomID(cid string) error {
@@ -37,28 +42,37 @@ func RandomID() string {
 }
 
 // ID returns the platform specific machine id of the current host OS.
-// If ID cannot be generated, a random value is suggested.
-func ID() (string, error) {
+// If ID cannot be generated, a random one from settings will be used (generated on demand)
+func ID() string {
 	if id == "" {
 		var err error
-		if id, err = machineid.ID(); err != nil {
-			rid := RandomID()
-			return "", fmt.Errorf("could not get %w; for manual configuration use plant: %s", err, rid)
+		if id, err = getMachineID(); err == nil && id != "" {
+			return id
 		}
+
+		// no machine id found, use is from settings
+		return getOrCreateIDFromSettings()
 	}
 
-	return id, nil
+	return id
+}
+
+// getOrCreateIDFromSettings return instance id from settings if exists, otherwise creates and stores a new one
+func getOrCreateIDFromSettings() string {
+	if id, err := settings.String(keys.Plant); err == nil && id != "" {
+		return id
+	}
+
+	id := RandomID()
+	settings.SetString(keys.Plant, id)
+
+	return id
 }
 
 // ProtectedID returns a hashed version of the machine id
 // using a fixed, application-specific key.
-func ProtectedID(key string) (string, error) {
-	id, err := ID()
-	if err != nil {
-		return id, err
-	}
-
-	return protect(key, id), nil
+func ProtectedID(key string) string {
+	return protect(key, ID())
 }
 
 // protect calculates HMAC-SHA256 of the id, keyed by key and returns a hex-encoded string

util/machine/machine_test.go

@@ -1,22 +1,65 @@
 package machine
 
 import (
+	"errors"
 	"testing"
 
 	"github.com/denisbrodbeck/machineid"
+	"github.com/evcc-io/evcc/core/keys"
+	"github.com/evcc-io/evcc/server/db/settings"
 )
 
 func TestProtectedMachineId(t *testing.T) {
 	const key = "foo"
 
 	if mid, err := machineid.ProtectedID(key); err == nil {
-		id, err := ProtectedID(key)
-		if err != nil {
-			t.Error(err)
-		}
+		id := ProtectedID(key)
 
 		if mid != id {
 			t.Errorf("machine id mismatch. expected %s, got %s", mid, id)
 		}
+	} else {
+		t.Skip("cannot get machineid, skipping test")
+	}
+}
+
+func TestIdFromSettings(t *testing.T) {
+	// reset machine id cache
+	id = ""
+
+	// reset settings
+	settings.Delete(keys.Plant)
+
+	// force machineid.ID() to fail
+	getMachineID = func() (string, error) {
+		return "", errors.New("dummy error")
+	}
+	t.Cleanup(func() {
+		getMachineID = machineid.ID
+	})
+
+	// generate new random id
+	generatedId := ID()
+	if len(generatedId) != 64 {
+		t.Errorf("expected 64 char id, got %d", len(generatedId))
+	}
+
+	// check that id is stored in settings
+	settingsId, _ := settings.String(keys.Plant)
+	if generatedId != settingsId {
+		t.Errorf("expected id %s, got %s from settings", generatedId, settingsId)
+	}
+
+	// check reproducability
+	idA1 := ProtectedID("A")
+	idA2 := ProtectedID("A")
+	idB := ProtectedID("B")
+
+	if idA1 != idA2 {
+		t.Errorf("expected same id, got %s and %s", idA1, idA2)
+	}
+
+	if idA1 == idB {
+		t.Errorf("expected different id, got %s and %s", idA1, idB)
 	}
 }