docs: make Prometheus Operator a strict requirement

Signed-off-by: Sunil Thaha <[email protected]>

Author: Sunil Thaha

README.md

@@ -31,8 +31,9 @@ kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/
 # Wait for cert-manager to be ready
 kubectl wait --for=condition=available --timeout=120s deployment -n cert-manager --all
 
-# 2. Install monitoring stack (Prometheus + Grafana)
-# Skip if you already have Prometheus installed
+# 2. Install Prometheus Operator (required for ServiceMonitor support)
+# This installs prometheus-operator + Prometheus + Grafana
+# If you only need prometheus-operator, see the monitoring stack guide
 helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
 helm install prometheus prometheus-community/kube-prometheus-stack \
   --namespace monitoring \

docs/user/README.md

@@ -17,17 +17,17 @@ Choose your platform to begin:
 ### Installation Guides
 
 - **[Kubernetes Installation (Helm)](installation/kubernetes.md)** - Install on vanilla Kubernetes using Helm
-  - Includes prerequisites: cert-manager setup
-  - Optional: Prometheus and Grafana setup
+  - Includes prerequisites: cert-manager and prometheus-operator
+  - Optional: Prometheus and Grafana for metrics visualization
 - **[OpenShift Installation (OperatorHub)](installation/openshift.md)** - Install via OperatorHub/OLM
   - Uses OpenShift's built-in certificate management
   - Integrates with OpenShift monitoring stack
 
 ### Prerequisites
 
-- **[Setting up Monitoring Stack on Kubernetes](installation/monitoring-stack-kubernetes.md)** - Optional guide for Prometheus and Grafana setup
-  - Required only if you want metrics visualization
-  - Not needed for basic Kepler installation
+- **[Setting up Monitoring Stack on Kubernetes](installation/monitoring-stack-kubernetes.md)** - Guide for prometheus-operator, Prometheus, and Grafana
+  - prometheus-operator is **REQUIRED** (Kepler Operator creates ServiceMonitor resources)
+  - Prometheus and Grafana are optional (needed only for metrics visualization)
 
 ## Guides
 
@@ -62,15 +62,23 @@ If you want to contribute to Kepler Operator or understand its internals, see th
 ### Kubernetes Quick Start
 
 ```bash
-# Install cert-manager
+# 1. Install cert-manager (required)
 kubectl apply -f https://github.com/cert-manager/cert-manager/releases/download/v1.18.2/cert-manager.yaml
 
-# Install Kepler Operator via Helm
+# 2. Install prometheus-operator (required)
+# Using kube-prometheus-stack (includes Prometheus + Grafana)
+helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
+helm install prometheus prometheus-community/kube-prometheus-stack \
+  --namespace monitoring \
+  --create-namespace \
+  --set prometheus.prometheusSpec.serviceMonitorSelectorNilUsesHelmValues=false
+
+# 3. Install Kepler Operator via Helm
 helm install kepler-operator ./manifests/helm/kepler-operator \
   --namespace kepler-operator \
   --create-namespace
 
-# Create PowerMonitor
+# 4. Create PowerMonitor
 kubectl apply -f - <<EOF
 apiVersion: kepler.system.sustainable.computing.io/v1alpha1
 kind: PowerMonitor

docs/user/installation/monitoring-stack-kubernetes.md

@@ -4,24 +4,30 @@ This guide helps you set up Prometheus and Grafana on vanilla Kubernetes to visu
 
 ## Overview
 
-Kepler exports metrics in Prometheus format. To visualize these metrics with Grafana dashboards, you need:
+Kepler exports metrics in Prometheus format. To use Kepler Operator, you need:
 
-1. **Prometheus** - To collect and store Kepler metrics
-2. **prometheus-operator** - To enable ServiceMonitor-based discovery (optional but recommended)
-3. **Grafana** - To visualize metrics with dashboards
+1. **prometheus-operator** - **REQUIRED** for ServiceMonitor support (Kepler Operator creates ServiceMonitor resources)
+2. **Prometheus** - Optional, to collect and store Kepler metrics for visualization
+3. **Grafana** - Optional, to visualize metrics with dashboards
 
-**Note**: This is a prerequisite guide, not part of Kepler Operator itself. Kepler Operator assumes you already have a monitoring solution if you want metrics visualization.
+**Important**: Kepler Operator requires prometheus-operator to be installed because it creates ServiceMonitor custom resources. You can install just prometheus-operator without Prometheus/Grafana, but you won't be able to collect or visualize metrics.
 
-## When Do You Need This?
+## What Do You Need?
 
-You need a monitoring stack if you want to:
+### Required: prometheus-operator
+
+**You MUST install prometheus-operator** before installing Kepler Operator. The operator will fail to reconcile PowerMonitor resources without it.
+
+### Optional: Full Monitoring Stack
+
+You need a complete monitoring stack (Prometheus + Grafana) if you want to:
 
 - Visualize energy consumption metrics in Grafana dashboards
 - Query historical power consumption data
 - Set up alerts based on energy usage
 - Integrate with existing monitoring infrastructure
 
-You can install Kepler Operator without a monitoring stack, but you won't be able to visualize metrics.
+You can install only prometheus-operator without Prometheus/Grafana, but Kepler metrics won't be collected or visualized.
 
 ## Quick Start: kube-prometheus-stack (Recommended)