Add Prometheus auto service discovery instructions to

prometheus.md

- Updated prometheus.md with instructions for setting up Prometheus auto service discovery for Dapr and sidecar targets.

Signed-off-by: Maulin Desai <mdesai@bosleo.com>

daprdocs/content/en/operations/observability/metrics/prometheus.md

@@ -93,13 +93,108 @@ helm install dapr-prom prometheus-community/prometheus -n dapr-monitoring
  --set alertmanager.persistence.enabled=false --set pushgateway.persistentVolume.enabled=false --set server.persistentVolume.enabled=false
 ```
 
+For automatic discovery of Dapr targets (Service Discovery), use:
+
+```bash
+  helm install dapr-prom prometheus-community/prometheus -f values.yaml -n dapr-monitoring --create-namespace
+```
+
+### `values.yaml` File
+
+```yaml
+alertmanager:
+  persistence:
+    enabled: false
+pushgateway:
+  persistentVolume:
+    enabled: false
+server:
+  persistentVolume:
+    enabled: false
+
+# Adds additional scrape configurations to prometheus.yml
+# Uses service discovery to find Dapr and Dapr sidecar targets
+extraScrapeConfigs: |-
+  - job_name: dapr-sidecars
+    kubernetes_sd_configs:
+      - role: pod
+    relabel_configs:
+      - action: keep
+        regex: "true"
+        source_labels:
+          - __meta_kubernetes_pod_annotation_dapr_io_enabled
+      - action: keep
+        regex: "true"
+        source_labels:
+          - __meta_kubernetes_pod_annotation_dapr_io_enable_metrics
+      - action: replace
+        replacement: ${1}
+        source_labels:
+          - __meta_kubernetes_namespace
+        target_label: namespace
+      - action: replace
+        replacement: ${1}
+        source_labels:
+          - __meta_kubernetes_pod_name
+        target_label: pod
+      - action: replace
+        regex: (.*);daprd
+        replacement: ${1}-dapr
+        source_labels:
+          - __meta_kubernetes_pod_annotation_dapr_io_app_id
+          - __meta_kubernetes_pod_container_name
+        target_label: service
+      - action: replace
+        replacement: ${1}:9090
+        source_labels:
+          - __meta_kubernetes_pod_ip
+        target_label: __address__
+
+  - job_name: dapr
+    kubernetes_sd_configs:
+      - role: pod
+    relabel_configs:
+      - action: keep
+        regex: dapr
+        source_labels:
+          - __meta_kubernetes_pod_label_app_kubernetes_io_name
+      - action: keep
+        regex: dapr
+        source_labels:
+          - __meta_kubernetes_pod_label_app_kubernetes_io_part_of
+      - action: replace
+        replacement: ${1}
+        source_labels:
+          - __meta_kubernetes_pod_label_app
+        target_label: app
+      - action: replace
+        replacement: ${1}
+        source_labels:
+          - __meta_kubernetes_namespace
+        target_label: namespace
+      - action: replace
+        replacement: ${1}
+        source_labels:
+          - __meta_kubernetes_pod_name
+        target_label: pod
+      - action: replace
+        replacement: ${1}:9090
+        source_labels:
+          - __meta_kubernetes_pod_ip
+        target_label: __address__
+```
+
 3. Validation
 
 Ensure Prometheus is running in your cluster.
 
 ```bash
 kubectl get pods -n dapr-monitoring
+```
 
+Expected output:
+
+```bash
 NAME                                                READY   STATUS    RESTARTS   AGE
 dapr-prom-kube-state-metrics-9849d6cc6-t94p8        1/1     Running   0          4m58s
 dapr-prom-prometheus-alertmanager-749cc46f6-9b5t8   2/2     Running   0          4m58s
@@ -110,6 +205,22 @@ dapr-prom-prometheus-pushgateway-688665d597-h4xx2   1/1     Running   0
 dapr-prom-prometheus-server-694fd8d7c-q5d59         2/2     Running   0          4m58s
 ```
 
+### Access the Prometheus Dashboard
+
+To view the Prometheus dashboard and check service discovery:
+
+```bash
+kubectl port-forward svc/dapr-prom-prometheus-server 9090:80 -n dapr-monitoring
+```
+
+Open a browser and visit `http://localhost:9090`. Navigate to `Status -> Service Discovery` to verify that the Dapr targets are discovered correctly.
+
+<img src="/images/prometheus-web-ui.png" alt="Prometheus Web UI" width="1200">
+
+You can see the `job_name` and its discovered targets.
+
+<img src="/images/prometheus-service-discovery.png" alt="Prometheus Service Discovery" width="1200">
+
 ## Example
 
 <div class="embed-responsive embed-responsive-16by9">