Unable to access the API endpoints through load balancer address

All the server addresses and ports are dummy.

I'm working on a microservices based project. I have deployed it to EC2 and ECS. Lets assume it has 2 services:

• EC2_SERVER_IP:8080 for authentication service APIs
• EC2_SERVER_IP:8081 for user service APIs

Now, I have decided to add a load balancer to EC2 cluster. I created a load balancer and mapped it with domain, https://api.com; and enabled the SSL on it.

Load Balancer Details: I have added a listener with Protocol:Port = HTTPS:443

I have created 2 target groups, dev-auth-tg and dev-user-tg. (linked with EC2 instance (EC2_SERVER_IP)). On dev-auth-tg, I have registered a target by selecting EC2 instance( EC2_SERVER_IP) and port 8080 On dev-user-tg, I have registered a target by selecting EC2 instance( EC2_SERVER_IP) and port 8081

For each target group, Protocol:Port = HTTPS:443 and protocol version is HTTP1. After that, I checked the state of instance and target group. Instance is "running", target group is "healthy" (means these are hitting API to get health status. I have implemented an endpoint / in root of each microservice and configure target group to get health status from there)

I have added 3 rules, one for authentication service, one for user service, and third is default.

Rule # 1: Path Pattern is /auth* Forward to target group: dev-auth-tg

Rule # 2: Path Pattern is /user* Forward to target group: dev-user-tg

Rule # 3: If no other rule applies Actions (Then) Return fixed response Response code: 503 Response body: Default Action

When I hit the endpoint: https://api.com/ It is returning the response generated by default rule.

Now, lets assume I have an endpoint, /customers in user microservice to get data of customers. So, when I hit the endpoint: https://api.com/user/customers it gives 502: Bad Gateway

But when I add something else than auth and user in endpoint, it redirects to default rule. So, it means rules are being working correctly.

Still when I hit APIs using domain address, it gives 502: Bad Gateway error. Can anyone please assist me to troubleshoot this issue?

Note: EC2 instance is up, Target groups are healthy, Security groups are added for inbound and outbound and SSL has been enabled.