Instrumenting HTTPX somehow breaks CORS in pyodide

[samuelcolvin]

Description

See https://pydantic.run/store/2394806888132a13

Code is

# /// script
# dependencies = ['logfire[httpx]', 'httpx']
# ///
import logfire
import httpx

logfire.configure(send_to_logfire=False)
logfire.instrument_httpx(capture_all=True)

r = httpx.get('https://global-power-plants.datasettes.com/global-power-plants.db')
r.raise_for_status()
print('datasize:', len(r.content))

If I comment out logfire.instrument_httpx(capture_all=True) it works fine.

Python, Logfire & OS Versions, related packages (not required)

logfire="3.4.0"
platform="Emscripten-3.1.58-wasm32-32bit"
python="3.12.7 (main, Jan 23 2025, 22:14:53) [Clang 19.0.0git (https:/github.com/llvm/llvm-project 0a8cd1ed1f4f35905df318015b"
[related_packages]
requests="2.31.0"
protobuf="5.29.2"
rich="13.7.1"
executing="2.0.1"
opentelemetry-api="1.29.0"
opentelemetry-exporter-otlp-proto-common="1.29.0"
opentelemetry-exporter-otlp-proto-http="1.29.0"
opentelemetry-instrumentation="0.50b0"
opentelemetry-instrumentation-httpx="0.50b0"
opentelemetry-proto="1.29.0"
opentelemetry-sdk="1.29.0"
opentelemetry-semantic-conventions="0.50b0"
opentelemetry-util-http="0.50b0"

[alexmojaki]

Access to XMLHttpRequest at 'https://global-power-plants.datasettes.com/global-power-plants.db' from origin 'https://pydantic.run' has been blocked by CORS policy: Request header field traceparent is not allowed by Access-Control-Allow-Headers in preflight response.

So we need to prevent context propagation in HTTP clients under pyodide.