1. 为什么 Agent 需要专门的可观测性 传统微服务可观测性关注请求-响应链路。Agent 系统则复杂得多:
多步骤推理:一个用户请求可能触发 10-50 次 LLM 调用 不确定输出:相同输入可能产生不同输出,难以复现问题 工具调用链:Agent → tool1 → Agent → tool2 → … 形成深层调用链 成本高昂:每次 LLM 调用都有实际成本,需要精准归因 幻觉风险:输出质量难以量化监控 普通监控工具(Prometheus/Grafana)只覆盖指标,无法完整追踪 Agent 行为。需要专门的 Agent 可观测性方案。
2. 可观测性三大支柱 ┌─────────────────────────────────────────────────┐ │ Agent Observability │ ├────────────┬──────────────┬────────────────────┤ │ Traces │ Metrics │ Logs │ │ (追踪) │ (指标) │ (日志) │ │ │ │ │ │ ┌────────┐ │ ┌────────┐ │ ┌──────────────┐ │ │ │Span │ │ │Counter │ │ │ Struct- │ │ │ │Tree │ │ │Gauge │ │ │ ured Log │ │ │ │Timeline│ │ │Histog. │ │ │ Event Log │ │ │ └────────┘ │ └────────┘ │ └──────────────┘ │ │ │ │ │ │ "发生了 │ "发生了几次" │ "发生了什么" │ │ 什么" │ "耗时多久" │ "为什么失败" │ └────────────┴──────────────┴────────────────────┘ 统一关联:TraceID + SpanID + LogID 3. 分布式追踪设计 3.1 Agent Span 模型 from dataclasses import dataclass, field from datetime import datetime from enum import Enum from typing import Optional import uuid class SpanKind(str, Enum): LLM_CALL = "llm_call" TOOL_CALL = "tool_call" AGENT_STEP = "agent_step" RETRIEVAL = "retrieval" USER_INPUT = "user_input" SYSTEM = "system" @dataclass class SpanContext: trace_id: str span_id: str parent_span_id: Optional[str] = None @dataclass class SpanEvent: name: str timestamp: datetime attributes: dict = field(default_factory=dict) @dataclass class AgentSpan: """Agent 追踪 Span - 兼容 OpenTelemetry""" trace_id: str span_id: str parent_span_id: Optional[str] kind: SpanKind name: str agent_id: str session_id: str # 时间 start_time: datetime = field(default_factory=datetime.now) end_time: Optional[datetime] = None duration_ms: Optional[float] = None # 输入/输出 input: dict = field(default_factory=dict) output: dict = field(default_factory=dict) # 状态 status: str = "ok" # ok, error, timeout error_message: Optional[str] = None # 成本 & 性能 token_usage: dict = field(default_factory=dict) # {input: N, output: N} cost_usd: float = 0.0 model: Optional[str] = None # 扩展属性 attributes: dict = field(default_factory=dict) events: list[SpanEvent] = field(default_factory=list) child_spans: list[str] = field(default_factory=list) # child span_ids def finish(self, status: str = "ok"): self.end_time = datetime.now() self.duration_ms = (self.end_time - self.start_time).total_seconds() * 1000 self.status = status def add_event(self, name: str, attributes: dict = None): self.events.append(SpanEvent( name=name, timestamp=datetime.now(), attributes=attributes or {} )) 3.2 追踪器实现 class AgentTracer: """Agent 分布式追踪器""" def __init__(self, exporter: "TraceExporter"): self.exporter = exporter self._active_spans: dict[str, AgentSpan] = {} # span_id -> span self._trace_tree: dict[str, list[str]] = {} # trace_id -> [span_ids] def start_trace(self, session_id: str, agent_id: str, name: str = "agent_session") -> tuple[str, str]: """开始一次 Agent 会话追踪""" trace_id = str(uuid.uuid4()) root_span_id = self._new_span_id() span = AgentSpan( trace_id=trace_id, span_id=root_span_id, parent_span_id=None, kind=SpanKind.AGENT_STEP, name=name, agent_id=agent_id, session_id=session_id, ) self._active_spans[root_span_id] = span self._trace_tree[trace_id] = [root_span_id] return trace_id, root_span_id def start_span(self, trace_id: str, parent_span_id: str, kind: SpanKind, name: str, agent_id: str, session_id: str, input_data: dict = None) -> str: span_id = self._new_span_id() span = AgentSpan( trace_id=trace_id, span_id=span_id, parent_span_id=parent_span_id, kind=kind, name=name, agent_id=agent_id, session_id=session_id, input=input_data or {}, ) self._active_spans[span_id] = span self._trace_tree.setdefault(trace_id, []).append(span_id) # 更新父 span 的 child 列表 if parent_span_id in self._active_spans: self._active_spans[parent_span_id].child_spans.append(span_id) return span_id def finish_span(self, span_id: str, output_data: dict = None, status: str = "ok", error: str = None): if span_id not in self._active_spans: return span = self._active_spans[span_id] span.finish(status) if output_data: span.output = output_data if error: span.error_message = error # 异步导出 asyncio.create_task(self.exporter.export_span(span)) def get_trace(self, trace_id: str) -> list[AgentSpan]: span_ids = self._trace_tree.get(trace_id, []) return [self._active_spans[sid] for sid in span_ids if sid in self._active_spans] @staticmethod def _new_span_id() -> str: return str(uuid.uuid4())[:16] # 短 ID,便于展示 3.3 OpenTelemetry 集成 from opentelemetry import trace from opentelemetry.sdk.trace import TracerProvider from opentelemetry.sdk.trace.export import BatchSpanProcessor from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import OTLPSpanExporter class OTelIntegration: """将 Agent Span 桥接到 OpenTelemetry""" def __init__(self, endpoint: str = "localhost:4317"): self.provider = TracerProvider() self.exporter = OTLPSpanExporter(endpoint=endpoint) self.processor = BatchSpanProcessor(self.exporter) self.provider.add_span_processor(self.processor) trace.set_tracer_provider(self.provider) self.tracer = trace.get_tracer("agent-system") def to_otel_span(self, agent_span: AgentSpan): """将 AgentSpan 转换为 OTel Span""" with self.tracer.start_as_current_span( agent_span.name, context=self._make_context(agent_span), kind=self._map_kind(agent_span.kind), ) as otel_span: # 设置属性 otel_span.set_attribute("agent.id", agent_span.agent_id) otel_span.set_attribute("session.id", agent_span.session_id) otel_span.set_attribute("llm.model", agent_span.model or "") otel_span.set_attribute("cost.usd", agent_span.cost_usd) for k, v in agent_span.token_usage.items(): otel_span.set_attribute(f"token.{k}", v) # 设置状态 if agent_span.status == "error": otel_span.set_status(trace.Status(trace.StatusCode.ERROR, agent_span.error_message)) # 添加事件 for evt in agent_span.events: otel_span.add_event(evt.name, evt.attributes) def _map_kind(self, kind: SpanKind): mapping = { SpanKind.LLM_CALL: trace.SpanKind.CLIENT, SpanKind.TOOL_CALL: trace.SpanKind.INTERNAL, SpanKind.AGENT_STEP: trace.SpanKind.INTERNAL, SpanKind.RETRIEVAL: trace.SpanKind.CLIENT, } return mapping.get(kind, trace.SpanKind.INTERNAL) 4. 指标采集 4.1 关键指标定义 from prometheus_client import Counter, Histogram, Gauge, Summary import time class AgentMetrics: """Agent 系统关键指标""" def __init__(self, namespace: str = "agent"): # LLM 调用指标 self.llm_requests = Counter( f"{namespace}_llm_requests_total", "Total LLM requests", ["model", "agent_id", "status"] ) self.llm_latency = Histogram( f"{namespace}_llm_latency_seconds", "LLM request latency", ["model", "agent_id"], buckets=[0.1, 0.5, 1.0, 2.0, 5.0, 10.0, 30.0, 60.0] ) self.llm_tokens = Counter( f"{namespace}_llm_tokens_total", "Total tokens consumed", ["model", "direction"] # direction: input/output ) self.llm_cost = Counter( f"{namespace}_llm_cost_usd_total", "Total LLM cost in USD", ["model", "agent_id"] ) # Agent 行为指标 self.agent_steps = Counter( f"{namespace}_agent_steps_total", "Total agent reasoning steps", ["agent_id", "step_type"] ) self.agent_session_duration = Histogram( f"{namespace}_agent_session_duration_seconds", "Agent session duration", ["agent_id", "outcome"] # outcome: success/failure/timeout ) self.agent_tool_calls = Counter( f"{namespace}_agent_tool_calls_total", "Total tool calls", ["agent_id", "tool_name", "status"] ) # 系统指标 self.active_sessions = Gauge( f"{namespace}_active_sessions", "Current active sessions", ["agent_id"] ) self.queue_depth = Gauge( f"{namespace}_queue_depth", "Current queue depth", ["queue_name"] ) self.error_rate = Summary( f"{namespace}_error_rate", "Error rate over 5m window", ["agent_id", "error_type"] ) def record_llm_call(self, model: str, agent_id: str, duration: float, input_tokens: int, output_tokens: int, cost: float, status: str): self.llm_requests.labels(model=model, agent_id=agent_id, status=status).inc() self.llm_latency.labels(model=model, agent_id=agent_id).observe(duration) self.llm_tokens.labels(model=model, direction="input").inc(input_tokens) self.llm_tokens.labels(model=model, direction="output").inc(output_tokens) self.llm_cost.labels(model=model, agent_id=agent_id).inc(cost) def record_agent_step(self, agent_id: str, step_type: str): self.agent_steps.labels(agent_id=agent_id, step_type=step_type).inc() def record_tool_call(self, agent_id: str, tool_name: str, status: str): self.agent_tool_calls.labels(agent_id=agent_id, tool_name=tool_name, status=status).inc() 4.2 成本归因指标 from collections import defaultdict class CostAttribution: """成本归因:按用户/会话/功能分解成本""" def __init__(self, redis_client): self.redis = redis_client async def record_cost(self, trace_id: str, user_id: str, feature: str, model: str, cost: float, tokens: int): pipe = self.redis.pipeline() # 按用户聚合 pipe.incrbyfloat(f"cost:user:{user_id}:total", cost) pipe.incrby(f"cost:user:{user_id}:tokens", tokens) # 按功能聚合 pipe.incrbyfloat(f"cost:feature:{feature}:total", cost) # 按模型聚合 pipe.incrbyfloat(f"cost:model:{model}:total", cost) # 按 trace 明细 pipe.hset(f"cost:trace:{trace_id}", mapping={ "user_id": user_id, "feature": feature, "model": model, "cost": str(cost), "tokens": str(tokens), "timestamp": str(time.time()) }) await pipe.execute() async def get_user_cost_report(self, user_id: str, days: int = 7) -> dict: return { "total_cost_usd": float(await self.redis.get(f"cost:user:{user_id}:total") or 0), "total_tokens": int(await self.redis.get(f"cost:user:{user_id}:tokens") or 0), "by_feature": await self._get_by_dimension(f"cost:feature", user_id, days), "by_model": await self._get_by_dimension(f"cost:model", user_id, days), } 5. 结构化日志 5.1 日志格式规范 import json import logging import sys from datetime import datetime from typing import Any class StructuredLogger: """结构化日志:JSON 格式,便于 ELK/Loki 检索""" def __init__(self, service_name: str, level: str = "INFO"): self.service = service_name self.logger = logging.getLogger(service_name) self.logger.setLevel(getattr(logging, level)) handler = logging.StreamHandler(sys.stdout) handler.setFormatter(self) self.logger.addHandler(handler) def format(self, record: logging.LogRecord) -> str: log_entry = { "timestamp": datetime.utcnow().isoformat() + "Z", "level": record.levelname, "service": self.service, "message": record.getMessage(), "trace_id": getattr(record, "trace_id", None), "span_id": getattr(record, "span_id", None), "session_id": getattr(record, "session_id", None), "agent_id": getattr(record, "agent_id", None), "user_id": getattr(record, "user_id", None), } # 添加额外字段 if hasattr(record, "extra_fields"): log_entry.update(record.extra_fields) return json.dumps(log_entry, ensure_ascii=False) def bind(self, **kwargs) -> "BoundLogger": return BoundLogger(self, kwargs) class BoundLogger: """绑定上下文的 Logger""" def __init__(self, logger: StructuredLogger, bound: dict): self._logger = logger self._bound = bound def _log(self, level: str, msg: str, **kwargs): extra = {**self._bound, **kwargs} record = self._logger.logger.makeRecord( self._logger.logger.name, getattr(logging, level), "(unknown)", 0, msg, [], None ) record.extra_fields = extra for k, v in extra.items(): setattr(record, k, v) self._logger.logger.handle(record) def info(self, msg: str, **kwargs): self._log("INFO", msg, **kwargs) def warning(self, msg: str, **kwargs): self._log("WARNING", msg, **kwargs) def error(self, msg: str, **kwargs): self._log("ERROR", msg, **kwargs) def debug(self, msg: str, **kwargs): self._log("DEBUG", msg, **kwargs) 5.2 日志事件类型 class AgentLogEvents: """Agent 关键生命周期事件""" @staticmethod def session_started(logger: BoundLogger, session_id: str, user_id: str): logger.info("agent.session.started", session_id=session_id, user_id=user_id, event_type="session_lifecycle") @staticmethod def llm_call_started(logger: BoundLogger, model: str, prompt_length: int): logger.info("llm.call.started", model=model, prompt_length=prompt_length, event_type="llm_call") @staticmethod def llm_call_completed(logger: BoundLogger, model: str, latency_ms: float, input_tokens: int, output_tokens: int, cost: float): logger.info("llm.call.completed", model=model, latency_ms=latency_ms, input_tokens=input_tokens, output_tokens=output_tokens, cost_usd=cost, event_type="llm_call") @staticmethod def tool_call_started(logger: BoundLogger, tool_name: str, args: dict): logger.info("tool.call.started", tool_name=tool_name, tool_args=args, event_type="tool_call") @staticmethod def tool_call_completed(logger: BoundLogger, tool_name: str, success: bool, result_summary: str): logger.info("tool.call.completed", tool_name=tool_name, success=success, result_summary=result_summary[:200], event_type="tool_call") @staticmethod def hallucination_detected(logger: BoundLogger, claim: str, confidence: float): logger.warning("agent.hallucination.detected", claim=claim[:100], confidence=confidence, event_type="quality") @staticmethod def session_completed(logger: BoundLogger, session_id: str, total_steps: int, total_cost: float, outcome: str): logger.info("agent.session.completed", session_id=session_id, total_steps=total_steps, total_cost_usd=total_cost, outcome=outcome, event_type="session_lifecycle") 6. 完整可观测性集成 class ObservableAgent: """集成可观测性的 Agent 基类""" def __init__(self, agent_id: str, tracer: AgentTracer, metrics: AgentMetrics, logger: StructuredLogger): self.agent_id = agent_id self.tracer = tracer self.metrics = metrics self.logger = logger.bind(agent_id=agent_id) self._current_trace_id: str | None = None self._current_span_id: str | None = None async def run(self, user_query: str, user_id: str, session_id: str) -> str: # 开始追踪 trace_id, root_span_id = self.tracer.start_trace(session_id, self.agent_id) self._current_trace_id = trace_id self._current_span_id = root_span_id # 绑定 trace 上下文到日志 self.logger = self.logger.bind(trace_id=trace_id, session_id=session_id, user_id=user_id) session_start = time.time() try: self.logger.info("agent.session.started", query=user_query[:100]) self.metrics.active_sessions.labels(agent_id=self.agent_id).inc() # 执行 Agent 逻辑(带追踪) result = await self._execute_with_tracing(user_query) duration = time.time() - session_start self.metrics.agent_session_duration.labels( agent_id=self.agent_id, outcome="success" ).observe(duration) self.logger.info("agent.session.completed", duration_seconds=duration, outcome="success") self.tracer.finish_span(root_span_id, {"result": result}, "ok") return result except Exception as e: duration = time.time() - session_start self.metrics.agent_session_duration.labels( agent_id=self.agent_id, outcome="failure" ).observe(duration) self.logger.error("agent.session.failed", error=str(e), exc_info=True) self.tracer.finish_span(root_span_id, status="error", error=str(e)) raise finally: self.metrics.active_sessions.labels(agent_id=self.agent_id).dec() async def _execute_with_tracing(self, query: str) -> str: # LLM 调用 llm_span_id = self.tracer.start_span( self._current_trace_id, self._current_span_id, SpanKind.LLM_CALL, "llm_chat", self.agent_id, self._get_session_id(), {"query": query} ) llm_start = time.time() try: self.logger.info("llm.call.started") response = await self._call_llm(query) latency = time.time() - llm_start self.metrics.record_llm_call( model="gpt-4o", agent_id=self.agent_id, duration=latency, input_tokens=100, output_tokens=50, cost=0.003, status="ok" ) self.tracer.finish_span(llm_span_id, {"response": response}, "ok") return response except Exception as e: self.tracer.finish_span(llm_span_id, status="error", error=str(e)) raise def _get_session_id(self) -> str: return self.logger._bound.get("session_id", "") 7. 可观测性数据流水线 Agent 运行时 │ ├── Traces ──→ OTel Collector ──→ Jaeger/Tempo ──→ Grafana │ ├── Metrics ──→ Prometheus ──────────────────────→ Grafana │ └── Logs ────→ Loki/ELK ───────────────────────→ Grafana │ └──→ 告警规则 → AlertManager → Slack/PagerDuty 7.1 OpenTelemetry Collector 配置 # otel-collector-config.yaml receivers: otlp: protocols: grpc: endpoint: 0.0.0.0:4317 http: endpoint: 0.0.0.0:4318 processors: batch: timeout: 5s send_batch_size: 100 memory_limiter: check_interval: 5s limit_mib: 1000 attributes: actions: - key: agent.id action: insert value: "unknown" resource: attributes: - key: deployment.environment value: "production" action: insert exporters: otlp/jaeger: endpoint: jaeger:4317 tls: insecure: true prometheus: endpoint: 0.0.0.0:8889 loki: endpoint: http://loki:3100/loki/api/v1/push service: pipelines: traces: receivers: [otlp] processors: [batch, memory_limiter, attributes] exporters: [otlp/jaeger] metrics: receivers: [otlp] processors: [batch, memory_limiter] exporters: [prometheus] logs: receivers: [otlp] processors: [batch, memory_limiter] exporters: [loki] 8. 告警规则 # prometheus-alerts.yaml groups: - name: agent_alerts rules: - alert: AgentHighErrorRate expr: | sum(rate(agent_agent_steps_total{status="error"}[5m])) by (agent_id) / sum(rate(agent_agent_steps_total[5m])) by (agent_id) > 0.05 for: 2m labels: severity: warning annotations: summary: "Agent {{ $labels.agent_id }} 错误率超过 5%" - alert: AgentHighLatency expr: | histogram_quantile(0.95, sum(rate(agent_llm_latency_seconds_bucket[5m])) by (le, agent_id) ) > 5 for: 2m labels: severity: warning annotations: summary: "Agent {{ $labels.agent_id }} P95 延迟超过 5 秒" - alert: AgentHighCost expr: | rate(agent_llm_cost_usd_total[1h]) > 10 for: 5m labels: severity: critical annotations: summary: "Agent 每小时成本超过 $10" - alert: AgentHallucinationDetected expr: | increase(agent_quality_hallucination_total[10m]) > 5 labels: severity: warning annotations: summary: "检测到 {{ $value }} 次幻觉" 9. 总结 Agent 可观测性的核心在于全链路关联:
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