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How to Mock OpenTelemetry Tracer Setup in Python
Set up a mock OpenTelemetry tracer with an in-memory span exporter to capture spans for testing and debugging.
from opentelemetry import trace
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import SimpleSpanProcessor
from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter
def setup_tracer():
provider = TracerProvider()
exporter = InMemorySpanExpo…How to Add a Correlation ID Tracing Header in Python
A mock middleware generates or preserves a correlation ID header and logs structured JSON messages with it for API request tracing.
import uuid
import json
from dataclasses import dataclass, field
from typing import Optional
@dataclass
class Request:
headers: dict = field(default_factory=dict)
def get(self, key, default=None):
return self.headers.get(key, default)
class CorrelationIdMiddleware:
def __init__(self, header_name…How to Propagate X-Request-ID in Python
Generate a unique request ID when one is missing and pass it through API calls for distributed tracing.
import uuid
def generate_request_id() -> str:
"""Generate a unique request ID similar to X-Request-ID header."""
return str(uuid.uuid4())
def propagate_request_id(request_id: str | None) -> str:
"""Return the request ID for propagation, generating one if missing."""
if request_id:
return re…How to Add Metadata Attributes to a Span in Python
Create a lightweight dataclass-based Span mock that stores key-value metadata attributes for tracing or event logging.
from dataclasses import dataclass, field
from typing import Dict, Any
@dataclass
class Span:
name: str
attributes: Dict[str, Any] = field(default_factory=dict)
def set_attribute(self, key: str, value: Any) -> None:
self.attributes[key] = value
def get_attribute(self, key: str) -> Any…How to Generate and Propagate W3C Trace Context Headers in Python
Generate and propagate W3C traceparent and tracestate headers for distributed tracing in Python, with mock service headers.
import uuid
def generate_w3c_traceparent(trace_id=None, parent_id=None, flags="01"):
if trace_id is None:
trace_id = uuid.uuid4().hex[:32]
if parent_id is None:
parent_id = uuid.uuid4().hex[:16]
return f"00-{trace_id}-{parent_id}-{flags}"
def create_mock_headers(service_name, trace_id=N…How to Mock a Baggage Context (Key-Value Store) in Python
This code implements an in-memory key-value mock of a baggage context, letting you set, get, check, and delete keys for tracing-style metadata.
class BaggageContext:
def __init__(self):
self._store = {}
def set(self, key, value):
self._store[key] = value
return value
def get(self, key, default=None):
return self._store.get(key, default)
def has(self, key):
return key in self._store
def delete(sel…How to Mock an OTLP HTTP Endpoint in Python
This code implements a lightweight HTTP server that accepts OTLP/HTTP trace exports, stores spans by trace ID, and exposes them via a simple GET endpoint for debugging.
import json
from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
from collections import defaultdict
class TraceHandler(BaseHTTPRequestHandler):
traces = defaultdict(list)
def do_POST(self):
if self.path == "/v1/traces":
length = int(self.headers.get("Content-Length", 0))
…How to Model Span Events in Python
Define a Span class with timestamped milestone events and a completion marker to track operation lifecycle.
import time
from dataclasses import dataclass, field
from enum import Enum
from typing import List
class SpanStatus(Enum):
STARTED = "started"
COMPLETED = "completed"
@dataclass
class SpanEvent:
name: str
timestamp: float = field(default_factory=time.time)
attributes: dict = field(default_facto…How to Simulate Trace Sampling Head in Python
Simulate head-based probabilistic trace sampling on mock trace data with a configurable sample rate and optional seed for reproducibility.
import random
def trace_sampling_head(mock_traces, sample_rate=0.5, seed=None):
"""Simulate probabilistic trace sampling (head-based) on mock data.
Args:
mock_traces: list of trace dictionaries with a unique 'trace_id'
sample_rate: float 0.0-1.0, probability of keeping a trace
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