Docker EE UCP – How to resolve x509 error when deploying stack?

I have installed and configured UCP with 3 manager nodes behind an external load balancer. There are also 6 workder nodes. I can run the UCP Web UI, but when I try to deploy a stack, I get an error. Deploying a stack via the command line on a manager node also works fine.

Here is my setup screen:

Screenshot of Stack Deploy

docker-compse.yml

version: "3.5"
services:

  nginx:
    image: nginx:1-alpine
    ports:
    - 8000:80

And then I get the following error message within the Web UI “console” output:

error during connect: Get https://<myucp-load-balancer>:443/v1.39/info: x509: certificate signed by unknown authority

Screenshot of error message

I am running on RHEL7 and have trusted the self-signed cert/ca at the system level on ALL nodes in the cluster. Does docker or UCP have its own trust store?

Is there another way to tell UCP to trust the self-signed cert for its own load balancer?

Source: StackOverflow