Read loading over bucket name from env var

internal/registry/types.bucket.go

@@ -259,6 +259,11 @@ func (b *Bucket) UpdateLabelsForBuild(componentType string, data map[string]stri
 
 // Load defaults from environment variables
 func (b *Bucket) LoadDefaultSettingsFromEnv() {
+	// Configure HCP Packer Registry destination
+	if b.Slug == "" {
+		b.Slug = os.Getenv(env.HCPPackerBucket)
+	}
+
 	// Set some iteration values. For Packer RunUUID should always be set.
 	// Creating an iteration differently? Let's not overwrite a UUID that might be set.
 	if b.Iteration.RunUUID == "" {