[DPE-5659] Update COS alert rules (#519)

* Changed description field to literal style

Using `|` character for easier editing of multi-line strings in the description field. Each line break in the yaml represents a newline character.

* Apply suggestions from code review

Co-authored-by: Paulo Machado <[email protected]>

* Update metrics_alert_rules.yaml

* Update metrics_alert_rules.yaml

Updates from a review meeting with Mohamed.

* Adding 'K8s' to group name to match PostgreSQL

---------

Co-authored-by: Paulo Machado <[email protected]>

Author: a-velasco

src/prometheus_alert_rules/metrics_alert_rules.yaml

@@ -1,5 +1,5 @@
 groups:
-  - name: MySQLExporter
+  - name: MySQLExporterK8s
 
     rules:
       # 2.1.1
@@ -9,8 +9,9 @@ groups:
         labels:
           severity: critical
         annotations:
-          summary: MySQL Down (instance {{ $labels.instance }})
-          description: "MySQL instance is down\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
+          summary: MySQL instance {{ $labels.instance }} is down. 
+          description: |
+            LABELS = {{ $labels }}.
 
       # 2.1.2
       # customized: 80% -> 90%
@@ -20,18 +21,10 @@ groups:
         labels:
           severity: warning
         annotations:
-          summary: MySQL too many connections (> 90%) (instance {{ $labels.instance }})
-          description: "More than 90% of MySQL connections are in use on {{ $labels.instance }}\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
-
-      # 2.1.3
-      - alert: MySQLHighPreparedStatementsUtilization(>80%)
-        expr: max_over_time(mysql_global_status_prepared_stmt_count[1m]) / mysql_global_variables_max_prepared_stmt_count * 100 > 80
-        for: 2m
-        labels:
-          severity: warning
-        annotations:
-          summary: MySQL high prepared statements utilization (> 80%) (instance {{ $labels.instance }})
-          description: "High utilization of prepared statements (>80%) on {{ $labels.instance }}\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
+          summary: MySQL instance {{ $labels.instance }} is using > 90% of `max_connections`.
+          description: |
+            Consider checking the client application responsible for generating those additional connections.
+            LABELS = {{ $labels }}. 
 
       # 2.1.4
       # customized: 60% -> 80%
@@ -41,8 +34,22 @@ groups:
         labels:
           severity: warning
         annotations:
-          summary: MySQL high threads running (instance {{ $labels.instance }})
-          description: "More than 80% of MySQL connections are in running state on {{ $labels.instance }}\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
+          summary: MySQL instance {{ $labels.instance }} is actively using > 80% of `max_connections`.
+          description: |
+            Consider reviewing the value of the `max-connections` config parameter or allocate more resources to your database server. 
+            LABELS = {{ $labels }}. 
+            
+      # 2.1.3
+      - alert: MySQLHighPreparedStatementsUtilization(>80%)
+        expr: max_over_time(mysql_global_status_prepared_stmt_count[1m]) / mysql_global_variables_max_prepared_stmt_count * 100 > 80
+        for: 2m
+        labels:
+          severity: warning
+        annotations:
+          summary:  MySQL instance {{ $labels.instance }} is using > 80% of `max_prepared_stmt_count`.
+          description: |
+            Too many prepared statements might consume a lot of memory. 
+            LABELS = {{ $labels }}. 
 
       # 2.1.8
       # customized: warning -> info
@@ -52,8 +59,10 @@ groups:
         labels:
           severity: info
         annotations:
-          summary: MySQL slow queries (instance {{ $labels.instance }})
-          description: "MySQL server mysql has some new slow query.\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
+          summary: MySQL instance {{ $labels.instance }} has a slow query.
+          description: |
+            Consider optimizing the query by reviewing its execution plan, then rewrite the query and add any relevant indexes. 
+            LABELS = {{ $labels }}.
 
       # 2.1.9
       - alert: MySQLInnoDBLogWaits
@@ -62,8 +71,11 @@ groups:
         labels:
           severity: warning
         annotations:
-          summary: MySQL InnoDB log waits (instance {{ $labels.instance }})
-          description: "MySQL innodb log writes stalling\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
+          summary: MySQL instance {{ $labels.instance }} has long InnoDB log waits. 
+          description: |
+            MySQL InnoDB log writes might be stalling. 
+            Check I/O activity on your nodes to find the responsible process or query. Consider using iotop and the performance_schema. 
+            LABELS = {{ $labels }}.
 
       # 2.1.10
       - alert: MySQLRestarted
@@ -72,5 +84,8 @@ groups:
         labels:
           severity: info
         annotations:
-          summary: MySQL restarted (instance {{ $labels.instance }})
-          description: "MySQL has just been restarted, less than one minute ago on {{ $labels.instance }}.\n  VALUE = {{ $value }}\n  LABELS = {{ $labels }}"
+          summary: MySQL instance {{ $labels.instance }} restarted.
+          description: |
+            MySQL restarted less than one minute ago. 
+            If the restart was unplanned or frequent, check Loki logs (e.g. `error.log`). 
+            LABELS = {{ $labels }}.