Interesting Solved... so what ca_file wants is Full Chain Cert (which is not clear what they are asking for normal a CA file is JUST the CA) .. so IMHO OTEL should specific that it wants a full chain certificate or this is some sort of bug
I got it to work.
So what I did is use Chrome and downloaded the full cert then set it as the ca_file and it connected ... I am not sure this adds any additional security.
then I set the cert
tls:
insecure: false
ca_file: test.cer
and the collector connected without the error!