How to use external Prometheus as a provider?

[DomineCore]

My Prometheus monitoring service is located in a cluster external saas services, I want to use it as the provider of sli, what should I do?

[agardnerIT]

Do these instructions help?
https://github.com/keptn-contrib/prometheus-service#using-an-external-prometheus-instance

[JJena]

For external prometheus, the instructions say to start with creating a secret for the external promethus. Do we still need prometheus-service in such case? I assume Yes.

I did both steps but still getting error Unable to detect prometheus.

sudo keptn create secret prometheus-credentials-keptn-evaluation --scope="keptn-prometheus-service" --from-literal="PROMETHEUS_USER=" --from-literal="PROMETHEUS_PASSWORD=" --from-literal="PROMETHEUS_URL=http://10.7.12.37:9090"
Secret prometheus-credentials-keptn-evaluation created successfully
[jjena@lt-injector-4 ~]$ sudo helm upgrade --install -n keptn prometheus-service https://github.com/keptn-contrib/prometheus-service/releases/download/0.9.1/prometheus-service-0.9.1.tgz --reuse-values
Release "prometheus-service" does not exist. Installing it now.
Error: execution error at (prometheus-service/templates/serviceaccount.yaml:41:30): Unable to detect Prometheus in the kubernetes cluster!