How to monitor an external none k8s system?

[TomHart]

I have my router configured to export Prometheus and wondered if it's possible to configure the kube-prometheus-stack to scrape it? Is there any docs/examples on how to scrape an external, none k8s system?

[mnlipp]

My question exactly. I need something like a ServiceMonitor/PodMonitor where the spec part simply defines a URL to scrape. Is this really not possible? (The fact that this has not been answered for such a long time does not give me much hope, though.) I'm afraid the (ridiculously complicated) solution is this: https://github.com/prometheus-operator/prometheus-operator/blob/main/Documentation/additional-scrape-config.md.

[oscgu]

For external systems I use something like the following + node_exporter as daemon:

apiVersion: v1
kind: Service
metadata:
  name: <name>
  namespace: <ns>
  labels:
    app: <name>
spec:
  ports:
  - name: metrics
    port: 9100
    protocol: TCP
    targetPort: 9100
---
kind: "Endpoints"
apiVersion: "v1"
metadata:
  name: <name>
  namespace: <ns>
subsets:
- addresses:
  - ip: <target-ip>
  ports:
  - name: metrics
    port: 9100
---
apiVersion: monitoring.coreos.com/v1
kind: ServiceMonitor
metadata:
  name: <name>
  namespace: <ns>
spec:
  endpoints:
  - port: metrics
  selector:
    matchLabels:
      app: <name>