protect unlock api endpoint

controllers/unlock.go

@@ -24,6 +24,11 @@ func Unlock(c *gin.Context) {
 	}
 	log.Println("Unlock received JSON input")
 
+	if models.CheckKeyProvided() {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "secret key can only be provided once after service start"})
+		return
+	}
+
 	// check that the key is 32 bytes long
 	if len(input.SecretKey) != 32 {
 		c.JSON(http.StatusBadRequest, gin.H{"error": "secret key provided is invalid, must be exactly 32 bytes long"})