Unable to Connect .NET Web API to ElastiCache Redis Cluster with AWS App Runner

Question

I have to redeploy a .NET Web Api application since AWS ECS with Docker is now archived / deprecated.

Doing so I'm using AWS Copilot to deploy an App Runner service.

I used a test application to learn the workflow and had it deployed with no issue. But now with the real application I cannot connect to my ElastiCache Redis Cluster. Keep in mind I had to switch regions (to support App Runner) and create a new Redis Cluster (from ca-central-1 to us-west-2).

Despite various security group configurations, I consistently receive the following error:

Unhandled exception. StackExchange.Redis.RedisConnectionException: It was not possible to connect to the redis server(s). Error connecting right now. To allow this multiplexer to continue retrying until it's able to connect, use abortConnect=false in your connection string or AbortOnConnectFail=false; in your code.

I also tried using the /addon/template.yml file to create the Redis cluster, but the error persists.

I verified in the log files that my endpoint for the cluster is correct.

Currently the inbound rule for the security group that is attached to the cluster is:

• Type: Custom TCP
• Port Range: 6379
• Source: Custom sg-***** (Security group the the app runner environment)

I have tried rules where I let all traffic in with 0.0.0.0 as the source ip.

I don't think it's the code because it was working with the previous deployment.

I have also tried adding multiple security groups that are all within the VPC but still the same error.

Has anyone encountered a similar issue or have any suggestions on what might be wrong?

Thank you!