How to add SSL certificate and make website HTTPS in AWS cloud?

Question

I have installed wordpress site on just 1 EC2 instance which is running on 1AZ (means 1 public subnet). I have bought a domain as well using Route 53. Currently my site is HTTP only which I want to make it HTTPS. I have got SSL certificate from AWS Certificate Manager as well. Using Route 53, currently I have mapped A record IP V4 mapping with my EC2 instance public IP V4 address. I'm facing issue here in changing my site to HTTPS from current HTTP. Since my site is deployed on just 1 AZ (public subnet), I cannot add Elastic Load Balancer in front of my EC2 instance as it requires minimum 2 public subnets (this is what my understanding is). If my side was deployed on 2 AZs (2 public subnets) then easily I would have configured Application Load Balancer with these 2 subnets and would have used the SSL certificate which is stored in AWS certificate manager but in my case it is just 1 AZ/1subnet.

Question 1) Is it necessary to have 2 public subnets to configure elastic load balancer? Can't I configure load balancer with just 1 subnet like in my case? If yes then please advise how to do it?

Question 2) Is load balancer really necessary between Route 53 and EC2 instance to make the site HTTPS? Can I configure Route 53 and SSL certificate to listen to EC2 instance directly and make the site HTTPS?

Please assist here to make my site HTTPS. Thanks

Answer 1

• 1) Yes, an ELB requires two subnets - but you dont have to have a server running in both subnets (but obviously you dont get the benefit/cost of dual servers). Within AWS goto the VPC section and create a new subnet inside the correct VPC - you should then be able to create an ELB (it may complain about the 2nd subnet - but if there are no instances inside that subnet it doesnt really matter).

• 2) No, but if you want to use the free ACM certificate it must be installed at the Load Balencer or CloudFront distribution level. There's nothing stopping you installing your own certificate on your EC2, configuring apache to use it and then renewing it as required. Take a look at LetsEncrypt for free certificates, or buy a cert online.

Few things to bare in mind:

• "Best Practise" for TLS/HTTPS is constantly changing. AWS take the headache out of this by providing policies so updating to the latest standard is very simple and requires no changes to your ec2 (as its talking to the ELB via port 80)
• If you decide to manage your own certificate, take a look at the SSL Labs certificate tester (https://www.ssllabs.com/ssltest/) to help you ensure your configuration is correct.

Answer 2

Let me answer the questions inline.

Question 1) Is it necessary to have 2 public subnets to configure elastic load balancer? Can't I configure load balancer with just 1 subnet like in my case? If yes then please advise how to do it?

Yes. You must specify subnets from at least two Availability Zones to increase the availability of your load balancer. This is why you need at least two subnets (Minimum one subnet in each Availability Zone). When you run the EC2 instances, it is also recommended to run them in both Availability Zones (Given to the Load Balancer) with Auto Scaling for high availability and fault tolerance.

Question 2) Is load balancer really necessary between Route 53 and EC2 instance to make the site HTTPS? Can I configure Route 53 and SSL certificate to listen to EC2 instance directly and make the site HTTPS?

It is necessory if you are using Amazon Certificate Manager (ACM) Issued SSL certificates. Otherwise, if you use an externally purchased SSL certificate, you can configure the SSL certificate at your EC2 instance web server level.

Note: An alternative approach is to use AWS CloudFront as a proxy (Also for SSL termination using ACM certificate) and proxy the requests to the EC2 instance (If you don't want to pay for the Load Balancer where CloudFront costs are based on the number of requests unlike an hourly charge for Load Balancer).