Hi I have some question about AWS ELB EC2 RDS 3 tier archite

Question

Hi I have some question about AWS ELB EC2 RDS 3 tier architecture in VPC I m first at IaC not good at aws and my code should be refactored but I need some helps and comprehensions about why my ELB or VPC or Web Server is not working <https github com SeongIkKim pulumi aws 3 tier blob master main py> This is my code and my ALB is not successful for health check and routing for my EC2 servers When I get into ALB public dns I see 502 BadGateway Error I know that this question is quietly broad but I can t get it anyway In my suspicion there are some points 1 ec2 LB security group I don t know how to attach my LB sg to ec2 It was easy in console but 2 VPC subnet is not well structured so My ALB is pointing some useless route 3 EC2 user data simplehttp WAS setting is not made In 3rd however I can t get logs because pulumi provises the instance without keypair I ve tried to get in ec2 with bastion host but there is no public key in instance

brave-angle-33257 · Answer

if you are an Admin on the AWS account you can probably get into the host using ssm system manager sessions

brave-angle-33257 · Answer

assuming the host is running a newer ubuntu or amzlinux image

brave-angle-33257 · Answer

you might need to add a role to the ec2 but then at least you can get onto the machine and curl locally to see if the web server is working

brave-angle-33257 · Answer

brave-angle-33257 · Answer

looking at the target group s targets should tell you if they are healthy or not

brave-angle-33257 · Answer

if not then make sure webserver is online make sure locally you can curl it review your target group health check settings check the path and port

brave-angle-33257 · Answer

if they aren t passing then likely is an issue between ALB and EC2 networking or security group usually i make the ingress on ALB be 80 443 no restriction on outbound

brave-angle-33257 · Answer

another good thing is to create a self referencing security group and apply that to the ALB the EC2 and the RDS that allows them to all communicate with eachother allow all traffic start with that makes it easier I dont tend to restrict outbound traffic

brave-angle-33257 · Answer

also make sure your VPC allows NACL traffic at the subnet level

brave-angle-33257 · Answer

even though security group allows it doesnt mean subnet or vpc does

brave-angle-33257 · Answer

good luck

numerous-barista-36019 · Answer

< brave angle 33257> really THANKS for your comments I got the real cause of my problem ec2 user data script because ubuntu 20 04 supports only python3 http server not python SimpleHTTPServer white frowning face Now my load balancer is healthy and I got really a little more exact view for VPC ALB Ports It s bit annoying but interesting You re comment for ssm and ports really save me Thanks to you again

brave-angle-33257 · Answer

you re welcome