# =============================================================================
# AWOOOI Database Alerts
# =============================================================================
# 負責人: DevOps Commander
# 版本: v1.0
# 日期: 2026-03-29
# ADR: ADR-037 Phase B (Database Exporters)
#
# 告警目標: PostgreSQL (192.168.0.188:5432) + Redis (192.168.0.188:6380)
# =============================================================================

apiVersion: monitoring.coreos.com/v1
kind: PrometheusRule
metadata:
  name: database-alerts
  namespace: monitoring
  labels:
    release: prometheus
    app: prometheus
spec:
  groups:
    # =========================================================================
    # PostgreSQL 告警
    # =========================================================================
    - name: postgresql
      rules:
        # -----------------------------------------------------------------
        # 連接池即將耗盡 (> 80%)
        # -----------------------------------------------------------------
        - alert: PostgreSQLConnectionPoolNearLimit
          expr: |
            sum(pg_stat_activity_count{state="active"}) by (datname) > 80
          for: 5m
          labels:
            severity: warning
            service: postgres
            team: infra
          annotations:
            summary: "PostgreSQL 活躍連接數過高"
            description: "Database {{ $labels.datname }} 活躍連接: {{ $value }}"
            runbook_url: "https://awoooi.internal/runbooks/postgres-connections"

        # -----------------------------------------------------------------
        # 連接池耗盡 (> 95%)
        # -----------------------------------------------------------------
        - alert: PostgreSQLConnectionPoolExhausted
          expr: |
            sum(pg_stat_activity_count{state="active"}) by (datname) > 95
          for: 2m
          labels:
            severity: critical
            service: postgres
            team: infra
          annotations:
            summary: "PostgreSQL 連接池即將耗盡"
            description: "Database {{ $labels.datname }} 活躍連接 > 95"

        # -----------------------------------------------------------------
        # 慢查詢過多
        # -----------------------------------------------------------------
        - alert: PostgreSQLSlowQueries
          expr: pg_slow_queries > 5
          for: 5m
          labels:
            severity: warning
            service: postgres
            team: backend
          annotations:
            summary: "PostgreSQL 慢查詢數量過多"
            description: "User {{ $labels.usename }} 有 {{ $value }} 個慢查詢 (> 1s)"

        # -----------------------------------------------------------------
        # 鎖等待過多
        # -----------------------------------------------------------------
        - alert: PostgreSQLLockWaiting
          expr: sum(pg_locks_waiting) > 10
          for: 2m
          labels:
            severity: warning
            service: postgres
            team: backend
          annotations:
            summary: "PostgreSQL 鎖等待過多"
            description: "{{ $value }} 個查詢正在等待鎖"

        # -----------------------------------------------------------------
        # 表膨脹 (Dead Tuple > 20%)
        # -----------------------------------------------------------------
        - alert: PostgreSQLTableBloat
          expr: pg_stat_user_tables_bloat_dead_tuple_ratio > 20
          for: 30m
          labels:
            severity: warning
            service: postgres
            team: infra
          annotations:
            summary: "PostgreSQL 表膨脹嚴重"
            description: "Table {{ $labels.relname }} dead tuple 比例: {{ $value }}%"

        # -----------------------------------------------------------------
        # 資料庫不可達
        # -----------------------------------------------------------------
        - alert: PostgreSQLDown
          expr: pg_up == 0
          for: 1m
          labels:
            severity: critical
            service: postgres
            team: infra
          annotations:
            summary: "PostgreSQL 無法連線"
            description: "PostgreSQL Exporter 無法連接到資料庫"

        # -----------------------------------------------------------------
        # 長時間執行查詢 (> 60s)
        # -----------------------------------------------------------------
        - alert: PostgreSQLLongRunningQuery
          expr: pg_longest_query_seconds > 60
          for: 1m
          labels:
            severity: warning
            service: postgres
            team: backend
          annotations:
            summary: "PostgreSQL 長時間執行查詢"
            description: "User {{ $labels.usename }} 查詢已執行 {{ $value | humanizeDuration }}"

        # -----------------------------------------------------------------
        # 高 Rollback 率 (> 5%)
        # -----------------------------------------------------------------
        - alert: PostgreSQLHighRollbackRate
          expr: pg_stat_database_transactions_rollback_ratio > 5
          for: 15m
          labels:
            severity: warning
            service: postgres
            team: backend
          annotations:
            summary: "PostgreSQL 事務回滾率過高"
            description: "Database {{ $labels.datname }} 回滾率: {{ $value }}%"

    # =========================================================================
    # Redis 告警
    # =========================================================================
    - name: redis
      rules:
        # -----------------------------------------------------------------
        # 記憶體使用過高 (> 85%)
        # -----------------------------------------------------------------
        - alert: RedisMemoryHigh
          expr: |
            redis_memory_max_bytes > 0 and redis_memory_used_bytes / redis_memory_max_bytes > 0.85
          for: 5m
          labels:
            severity: warning
            service: redis
            team: infra
          annotations:
            summary: "Redis 記憶體使用 > 85%"
            description: "Redis 記憶體使用: {{ $value | humanizePercentage }}"

        # -----------------------------------------------------------------
        # 記憶體即將耗盡 (> 95%)
        # -----------------------------------------------------------------
        - alert: RedisMemoryCritical
          expr: |
            redis_memory_used_bytes / redis_memory_max_bytes > 0.95
          for: 2m
          labels:
            severity: critical
            service: redis
            team: infra
          annotations:
            summary: "Redis 記憶體即將耗盡"
            description: "Redis 記憶體使用 > 95%"

        # -----------------------------------------------------------------
        # 快取命中率過低 (< 80%)
        # -----------------------------------------------------------------
        - alert: RedisCacheHitRateLow
          expr: |
            rate(redis_keyspace_hits_total[5m])
            /
            (rate(redis_keyspace_hits_total[5m]) + rate(redis_keyspace_misses_total[5m]))
            < 0.8
          for: 15m
          labels:
            severity: warning
            service: redis
            team: backend
          annotations:
            summary: "Redis 快取命中率過低"
            description: "命中率: {{ $value | humanizePercentage }}"

        # -----------------------------------------------------------------
        # 連接數過高
        # -----------------------------------------------------------------
        - alert: RedisConnectionsHigh
          expr: redis_connected_clients > 500
          for: 5m
          labels:
            severity: warning
            service: redis
            team: infra
          annotations:
            summary: "Redis 連接數過高"
            description: "連接數: {{ $value }}"

        # -----------------------------------------------------------------
        # Key 驅逐頻繁
        # -----------------------------------------------------------------
        - alert: RedisEvictedKeys
          expr: rate(redis_evicted_keys_total[5m]) > 100
          for: 5m
          labels:
            severity: warning
            service: redis
            team: backend
          annotations:
            summary: "Redis Key 驅逐頻繁"
            description: "每秒驅逐 {{ $value }} 個 key"

        # -----------------------------------------------------------------
        # Redis 不可達
        # -----------------------------------------------------------------
        - alert: RedisDown
          expr: redis_up == 0
          for: 1m
          labels:
            severity: critical
            service: redis
            team: infra
          annotations:
            summary: "Redis 無法連線"
            description: "Redis Exporter 無法連接到 Redis"

        # -----------------------------------------------------------------
        # 命令延遲過高
        # -----------------------------------------------------------------
        - alert: RedisLatencyHigh
          expr: |
            redis_commands_duration_seconds_total / redis_commands_processed_total > 0.01
          for: 5m
          labels:
            severity: warning
            service: redis
            team: backend
          annotations:
            summary: "Redis 命令延遲過高"
            description: "平均命令延遲 > 10ms"

        # -----------------------------------------------------------------
        # 阻塞客戶端
        # -----------------------------------------------------------------
        - alert: RedisBlockedClients
          expr: redis_blocked_clients > 10
          for: 5m
          labels:
            severity: warning
            service: redis
            team: backend
          annotations:
            summary: "Redis 有阻塞的客戶端"
            description: "{{ $value }} 個客戶端被阻塞 (BLPOP/BRPOP)"