How to deploy SSL certificates on Amazon Elastic Container Service?

Question

I have a proxy server (nginx) which has the following responsibilities:

1. proxies to different backends depending on resource requested
2. enforces rate limiting and IP blacklisting
3. handles rewrites and url transformations
4. does SSL termination, has multiple certs & keys

The problem is it's a single point of failure, that's why I'm looking into Amazon ECS to achieve high availability and scalability.

Here's my setup:

1. Amazon ECS - EC2 instances (not Fargate) using an ALB
   • ALB will be my main entry point, traffic would be HTTPS
   • Traffic will then be forwarded to the proxy server (running tasks) which will handle SSL termination
2. Amazon ECR - This will hold my proxy server image, updated on rule changes
   • so far, I've built a simple nginx service with self-signed certs for testing

So my question is:

What is a good approach to deploy the SSL certs & keys to the task containers?

I'm not very familiar with AWS services, but I'd prefer to use an existing AWS solution.