Load Balancer Target Group

Hi AWS, I have a question i.e.

Does adding new target group with healthy instances and removing the old target group from the AWS load balancer in production makes any negative impacts?

Services involved: Launch template Load balancer Target groups Auto scaling group

This is the complete process:

Step1: We create stagging servers(which were spinned from the previous ami), push our jar, wars into the tomcat.

Step2: Creating images from that stagging servers. Attach it to the launch template. And set it as default version.

Step3: Now we drain one server from the target group, after successful draining we delete that server so new one spins. Until the new one becomes healthy we don't drain the second server.

Step4:

We remove second instance after checking the new spin instance become healthy and after successful draining of the second one we remove it and new will spin. Because of desired capacity is set to 2.

Having said that I want to automate this process as currently we are doing it manually and it is error prone and very time consuming. How can we effectively automate this process with the least cost possible in a more reliable and faster development mode.

Please help.