How do you get prometheus metrics from postgresql? - postgresql

Question

I have installed prometheus into my Kubernetes v1.17 KOPS cluster following kube-prometheus, ensuring the --authentication-token-webhook=true and --authorization-mode=Webhook prerequisets are set and the kube-prometheus/kube-prometheus-kops.libsonnet configuration specified.
I have then installed Postgres using https://github.com/helm/charts/tree/master/stable/postgresql using the supplied values-production.yaml with the following set:
metrics:
enabled: true
# resources: {}
service:
type: ClusterIP
annotations:
prometheus.io/scrape: "true"
prometheus.io/port: "9187"
loadBalancerIP:
serviceMonitor:
enabled: true
namespace: monitoring
interval: 30s
scrapeTimeout: 10s
Both services are up and working, but prometheus doesn't discover any metrics from Postgres.
The logs on the metrics container on my postgres pods have no errors, and neither do any of the pods in the monitoring namespace.
What additional steps are required to have the Postgres metrics exporter reach Prometheus?

Answer 1

Try to update ClusterRole for Prometheus. By default, it hasn't permissions to retrieve a list of pods, services, and endpoints from non-monitoring namespace.
In my system the original ClusterRole was:
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: prometheus-k8s
rules:
- apiGroups:
- ""
resources:
- nodes/metrics
verbs:
- get
- nonResourceURLs:
- /metrics
verbs:
- get
I've changed it to:
apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
name: prometheus-k8s
rules:
- apiGroups:
- ""
resources:
- nodes/metrics
- services
- endpoints
- pods
verbs:
- get
- list
- watch
- nonResourceURLs:
- /metrics
verbs:
- get
After those changes, Postgres metrics will be available for Prometheus.