Spring Boot Application deployed on Elastic Beanstalk Java environment returns 502

Nginx doesn't know on which port your spring boot applicaiton is running. Make application run on port 5000 that Nginx redirects to by default by adding "server.port=5000" to application.properties or other suggested ways in the last step:

https://pragmaticintegrator.wordpress.com/2016/07/12/run-your-spring-boot-application-on-aws-using-elastic-beanstalk/

From your question description and the security group settings you send me your only inbound Port 80 for your EC2 instance was open to world through firewall and you were using port 5000 for your application. So using the security rule that I gave you it opened the inbound port 5000 too for your EC2 instance so your application started working without above error.