Chapter 3: webserver-cluster ALB unable to access

[myysophia]

1. terraform apply
   `
   ....
   Outputs:

alb_dns_name = "terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com"

2. Access the domain name http 504 dig terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com

; <<>> DiG 9.11.4-P2-RedHat-9.11.4-26.P2.el7_9.14 <<>> terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12977
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1024
;; QUESTION SECTION:
;terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com. IN A

;; ANSWER SECTION:
terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com. 60 IN A 13.59.44.32
terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com. 60 IN A 3.22.65.52
terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com. 60 IN A 3.137.118.81

;; Query time: 68 msec
;; SERVER: 10.0.2.3#53(10.0.2.3)
;; WHEN: Wed Jan 10 17:25:38 CST 2024
;; MSG SIZE rcvd: 137

curl -I http://terraform-asg-example-1820730563.us-east-2.elb.amazonaws.com/
HTTP/1.1 504 Gateway Time-out
Server: awselb/2.0
Date: Wed, 10 Jan 2024 09:25:58 GMT
Content-Type: text/html
Content-Length: 132
Connection: keep-alive
`

3.Check that the back-end status is ok

4. ref repo
   Any help would be appreciated,3q