Use random_string resource for rds password.

[#153526683]

rds.tf

@@ -1,11 +1,16 @@
+resource "random_string" "rds_password" {
+  length  = 16
+  special = true
+}
+
 resource "aws_db_instance" "rds" {
   allocated_storage      = 100
   instance_class         = "${var.rds_instance_class}"
   engine                 = "mysql"
   engine_version         = "5.6.35"
   identifier             = "${var.env_name}"
   username               = "${var.rds_db_username}"
-  password               = "${md5(timestamp())}"
+  password               = "${random_string.rds_password.result}"
   db_subnet_group_name   = "${aws_db_subnet_group.rds_subnet_group.name}"
   publicly_accessible    = false
   vpc_security_group_ids = ["${aws_security_group.mysql_security_group.id}"]