多维指标监控体系搭建：Prometheus+Grafana的落地实践

一、从"服务活着吗"到"服务健康吗"

监控有三个层次：存活性监控（进程是否 alive）→技术指标监控（CPU/内存/QPS/延迟）→业务指标监控（评测成功率/用户留存/推荐点击率）。

多数团队停留在第一层，少部分到了第二层，极少数能把第三层落地。这套多维指标监控体系的目标是：同一套架构，覆盖三个层次，让每种角色都能在 Grafana 上找到自己需要的看板。

flowchart TB A[应用服务] -->|埋点 SDK| B[Metrics Exporter] A -->|健康探测| C[Health Prober] B --> D[Prometheus 拉取/推送] C --> D D --> E[AlertManager 告警规则] E --> F{告警类型} F -->|Critical| G[PagerDuty/电话] F -->|Warning| H[企业微信/钉钉] F -->|Info| I[记录到日志] D --> J[Grafana 可视化] J --> K[运维看板: 集群健康] J --> L[开发看板: 接口延迟] J --> M[产品看板: 业务指标] style D fill:#ccf style J fill:#cfc

二、四个黄金信号与指标设计

Google SRE 提出的四个黄金信号是监控的"最小可行指标"：

对于刷题系统，分级指标设计如下：

L1 存活性：up{job="judge-worker"}、process_resident_memory_bytes
L2 技术指标：http_request_duration_seconds、db_connection_active、gc_pause_seconds
L3 业务指标：judge_success_rate、recommend_click_rate、avg_solving_time_minutes

三、监控体系的核心实现

""" 监控指标埋点 SDK 实现 Prometheus 风格的 Counter/Gauge/Histogram """ import time import threading from typing import Dict, List, Optional, Callable from dataclasses import dataclass, field from collections import defaultdict class MetricType: COUNTER = "counter" GAUGE = "gauge" HISTOGRAM = "histogram" @dataclass class MetricLabel: """指标标签""" name: str value: str class Counter: """计数器：只增不减的累计值""" def __init__(self, name: str, help: str, labels: Optional[Dict[str, str]] = None): self.name = name self.help = help self.labels = labels or {} self._value: float = 0.0 self._lock = threading.Lock() def inc(self, amount: float = 1.0): """增加计数值""" with self._lock: self._value += amount def get(self) -> float: with self._lock: return self._value class Gauge: """仪表盘：可增可减的瞬时值""" def __init__(self, name: str, help: str, labels: Optional[Dict[str, str]] = None): self.name = name self.help = help self.labels = labels or {} self._value: float = 0.0 self._lock = threading.Lock() def set(self, value: float): """设置当前值""" with self._lock: self._value = value def inc(self, amount: float = 1.0): with self._lock: self._value += amount def dec(self, amount: float = 1.0): with self._lock: self._value -= amount def get(self) -> float: with self._lock: return self._value class Histogram: """直方图：记录值的分布""" def __init__(self, name: str, help: str, buckets: List[float], labels: Optional[Dict[str, str]] = None): self.name = name self.help = help self.buckets = sorted(buckets) self.labels = labels or {} self._bucket_counts: Dict[float, int] = defaultdict(int) self._sum: float = 0.0 self._count: int = 0 self._lock = threading.Lock() def observe(self, value: float): """观察一个值""" with self._lock: self._sum += value self._count += 1 for bound in self.buckets: if value <= bound: self._bucket_counts[bound] += 1 break def get_stats(self) -> Dict: """获取统计信息""" with self._lock: return { "count": self._count, "sum": self._sum, "buckets": dict(self._bucket_counts), } class MetricsRegistry: """指标注册中心（单例）""" _instance = None _lock = threading.Lock() def __new__(cls): if cls._instance is None: with cls._lock: if cls._instance is None: cls._instance = super().__new__(cls) cls._instance._metrics: Dict[str, object] = {} return cls._instance def register(self, metric): """注册指标""" self._metrics[metric.name] = metric def get(self, name: str): return self._metrics.get(name) def export_prometheus_format(self) -> str: """导出为 Prometheus 文本格式""" lines = [] for name, metric in self._metrics.items(): # HELP 和 TYPE 行 lines.append(f"# HELP {name} {getattr(metric, 'help', '')}") if isinstance(metric, Counter): lines.append(f"# TYPE {name} counter") lines.append(f"{name}{_format_labels(metric.labels)} " f"{metric.get()}") elif isinstance(metric, Gauge): lines.append(f"# TYPE {name} gauge") lines.append(f"{name}{_format_labels(metric.labels)} " f"{metric.get()}") elif isinstance(metric, Histogram): lines.append(f"# TYPE {name} histogram") stats = metric.get_stats() for bound, count in sorted(stats["buckets"].items()): lines.append( f'{name}_bucket{{le="{bound}"}}' f' {count}' ) lines.append(f"{name}_bucket{{le=\"+Inf\"}} " f"{stats['count']}") lines.append(f"{name}_sum {stats['sum']}") lines.append(f"{name}_count {stats['count']}") return "\n".join(lines) + "\n" def _format_labels(labels: Dict[str, str]) -> str: """格式化 Prometheus labels""" if not labels: return "" parts = [f'{k}="{v}"' for k, v in labels.items()] return "{" + ",".join(parts) + "}" # 全局注册中心 registry = MetricsRegistry() # 预定义指标 http_requests_total = Counter( "http_requests_total", "HTTP 请求总数", labels={"service": "api-gateway"}, ) registry.register(http_requests_total) active_db_connections = Gauge( "db_connections_active", "活跃数据库连接数", ) registry.register(active_db_connections) request_duration_seconds = Histogram( "http_request_duration_seconds", "HTTP 请求耗时分布", buckets=[0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1.0, 2.5, 5.0], ) registry.register(request_duration_seconds) judge_success_rate = Gauge( "judge_success_rate", "评测成功率", ) registry.register(judge_success_rate) # 常用的上下文管理器：自动记录请求耗时 class RequestTimer: """自动计时并记录到 Histogram""" def __init__(self, histogram: Histogram): self.histogram = histogram self._start = 0.0 def __enter__(self): self._start = time.time() return self def __exit__(self, *args): duration = time.time() - self._start self.histogram.observe(duration) # AlertManager 告警规则（YAML 格式示例） ALERT_RULES = """ groups: - name: api_alerts rules: - alert: HighErrorRate expr: rate(http_requests_total{status="500"}[5m]) > 0.05 for: 2m labels: severity: critical annotations: summary: "API 错误率超过 5%" - alert: HighLatency expr: histogram_quantile(0.99, rate(http_request_duration_seconds_bucket[5m])) > 1.0 for: 5m labels: severity: warning annotations: summary: "P99 延迟超过 1 秒" - alert: LowSuccessRate expr: judge_success_rate < 0.9 for: 5m labels: severity: critical annotations: summary: "评测成功率低于 90%" """ if __name__ == "__main__": with RequestTimer(request_duration_seconds): time.sleep(0.05) http_requests_total.inc() active_db_connections.set(8) judge_success_rate.set(0.95) print(registry.export_prometheus_format()) print(ALERT_RULES)

四、生产级监控的工程决策

指标基数控制：每个接口 × 每个状态码 × 每个服务 = 爆炸的指标数量。用relabel_config在 Prometheus 侧过滤低价值标签组合。

存储成本优化：30 天的高精度数据（15s 采集间隔）+ 1 年的聚合数据（5min 采集间隔）。用 Thanos/Cortex 做长期存储降采样。

告警收敛：同一个故障可能触发 10 条告警。设置告警分组规则（按服务/按时间窗口），避免告警风暴。

五、总结

1. 四个黄金信号是最小可行集：Latency/Traffic/Errors/Saturation，先覆盖这四个再扩展。
2. 分层次监控：L1 存活性、L2 技术指标、L3 业务指标，各层看板独立但数据互通。
3. Histogram 优于 Summary：Histogram 可以在 Prometheus 侧做任意分位计算，Summary 做不到。
4. 告警规则要审慎：告警太敏感→告警疲劳，太迟钝→故障发现延迟。

本文实现了一个 Prometheus 兼容的指标 SDK（Counter/Gauge/Histogram），包含 Prometheus 导出格式和 AlertManager 告警规则模板，可直接集成到后端服务中。