Address CodeRabbit review comments on monitoring module

Author: HiranAdikari

modules/monitoring/README.md

@@ -34,7 +34,7 @@ module "monitoring" {
 
 ## Architecture
 
-```
+```text
 Prometheus (rancher-monitoring)
    │  evaluates PrometheusRule CRDs labelled release=rancher-monitoring
    ▼
@@ -253,7 +253,7 @@ A Google Chat card should appear within a few seconds.
 Each alert produces one card. The card structure is defined in a Go template
 stored in the `calert-config` Secret and rendered by calert at runtime.
 
-```
+```text
 ┌─────────────────────────────────────────────────────┐
 │ (WARNING) LonghornDiskUsageHigh | Firing             │  ← header
 ├─────────────────────────────────────────────────────┤
@@ -269,7 +269,7 @@ stored in the `calert-config` Secret and rendered by calert at runtime.
 
 **"View Alert" button** is only rendered when `alertmanager_url` is set. It
 links to:
-```
+```text
 <alertmanager_url>/#/alerts?filter={alertname="<name>"}
 ```
 

modules/monitoring/examples/basic/main.tf

@@ -28,10 +28,10 @@ provider "kubernetes" {
 }
 
 module "monitoring" {
-  source = "github.com/wso2-enterprise/open-cloud-datacenter//modules/monitoring?ref=v0.3.0"
+  source = "../../"
 
   # Identifiers
-  environment        = "lk"
+  environment        = var.environment
   kubeconfig_path    = var.kubeconfig_path
   kubeconfig_context = var.kubeconfig_context
 
@@ -61,6 +61,11 @@ output "monitoring_resources" {
   }
 }
 
+variable "environment" {
+  type        = string
+  description = "Short environment identifier used in resource names (e.g. \"lk\")."
+}
+
 variable "kubeconfig_path" {
   type    = string
   default = "~/.kube/harvester-lk.yaml"

modules/monitoring/main.tf

@@ -486,7 +486,7 @@ resource "kubernetes_manifest" "prometheus_rule_storage" {
             },
             {
               alert  = "LonghornEvictionWithDegradedVolumes"
-              expr   = "longhorn_disk_eviction_requested == 1"
+              expr   = "longhorn_disk_eviction_requested == 1 and on() count(longhorn_volume_robustness{robustness=\"degraded\"}) > 0"
               for    = "5m"
               labels = { severity = "critical" }
               annotations = {