AWS database bug fixing

Systems were working perfectly. Then AWS sent this message - EC2 may schedule instances for retirement in cases where there is an unrecoverable issue with the underlying hardware. For more information about scheduled retirement events please see the EC2 user guide. [login to view URL] App and website stopped working. Showing error "502 Bad Gateway. nginx/1.10.3 (Ubuntu)". APIs stopped responding. Seems hardware issue from their side. I restarted the instance as suggested by AWS support team as it allocates the server to new working instance. Even after starting, the issue persists. I then further looked at the load balancer with prod Target Group name and noticed that this instance behind the target group was showing an unhealthy state with the reason specifying: “[login to view URL]” hence failing with 502 code. ResponseCodeMismatch mean that the health checks did not return an expected HTTP code. There are multiple possible causes of this HTTP 502 bad gateway error. Please kindly review the link below [1] for some of those possible causes and it also tell you on what you need to look at to try and troubleshoot this. After analyzing this and the ResponseCodeMismatch error on the target, I couldn’t find any obvious root cause for this behavior. Could you also please perform the below tests/configuration changes to troubleshoot this behavior? 1. Fix the response code at the backend so it matches the configuration on the health check: - Right now the health check on the ALB is configured to accept only HTTP 200 answers as valid answers, but the backend is returning a HTTP 502 response. - In order to avoid any issues, the first step would be making the backend healthy forcing a valid HTTP code on the health check path. - You'll need to check the backend application's behavior so it returns a valid response code and the configuration of the health check so it queries a valid path and accepts the proper response code [2]. - If a few minutes after fixing the health check the ALB is still returning HTTP 502 errors, the use of the Access Logs would allow you to see more details of these failing queries. [3] I need a experienced Devops guy at an affordable cost to resolve this minor issue. As far as the issue is concerned, according to AWS support team, database is not listening to server. Github repo of backend- [login to view URL] I need a smart Devops guy experienced in AWS who can resolve the issue fast.