ModuleNotFoundError: No module named opentelemetry w/ manual tracing

[agardnerIT]

Hi all,

Running python -m pytest --export-traces (without any OTEL code in my app.py) works perfectly.

After I add manual tracing code to my app.py, python -m pytest --export-traces fails with the error:

stderr='Traceback (most recent call las...", line 2, in <module>\n    from opentelemetry import trace\nModuleNotFoundError: No module named \'opentelemetry\'\n'

OS

Win11

Python Version

python --version
Python 3.11.3

requirements.txt

pytest==7.4.0
pytest-opentelemetry==0.6.2
opentelemetry-api==1.19.0
opentelemetry-sdk==1.19.0

The Code app.py

import argparse
import time
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
from opentelemetry.sdk.resources import SERVICE_NAME, Resource

parser = argparse.ArgumentParser()
parser.add_argument('-f', '--first', required=True, default="")
parser.add_argument('-s', '--second', required=True, default="")

def concat_strings(first, second):

    if first == "":
        return None
    if second == "":
        return None
    
    return first + " " + second

if __name__ == "__main__":

    # OpenTelemetry Boilerplate
    # Service name is required for most backends
    resource = Resource(attributes={
        SERVICE_NAME: "pytest-otel-demo"
    })

    provider = TracerProvider(resource=resource)
    processor = BatchSpanProcessor(OTLPSpanExporter(endpoint="localhost:4317", insecure=True))
    provider.add_span_processor(processor)
    trace.set_tracer_provider(provider)

    # Creates a tracer from the global tracer provider
    tracer = trace.get_tracer("my.tracer.name")

    with tracer.start_as_current_span("app.py"):
        with tracer.start_as_current_span("parse-args") as span:
            args = parser.parse_args()
            first = args.first
            second = args.second
            time.sleep(0.100) # sleep for 100ms
        
        with tracer.start_as_current_span(name="concat_strings") as concat_strings_span:
        
            concat_strings_span.set_attribute("first-string", first)
            concat_strings_span.set_attribute("second-string", second)
            
            result = concat_strings(first, second)

            concat_strings_span.set_attribute("result", result)

            time.sleep(0.200) # sleep for 200ms

app_test.py

import subprocess

def run_program(first="", second=""):
    output = subprocess.run(f"python3 app.py -f {first} -s {second}" , capture_output=True, shell=True, text=True)
    return output

# Run program with no input params
# Should error and so check error is present
def test_run_no_params():
    output = run_program()
    assert output.returncode != 0
    assert output.stderr != ""

# Run program with one input
# Should error so check
def test_run_with_only_first_param():
    output = run_program(first="foo")
    assert output.returncode != 0
    assert output.stderr != ""

# Run program as it should
# with two valid parameters
def test_run_with_both_valid_params(first="foo", second="bar"):
    output = run_program(first="foo", second="bar")
    assert output.returncode == 0
    assert output.stderr == ""
    assert "Result is: foo bar" in output.stdout

[The-Compiler]

This seems entirely unrelated to pytest itself - pytest knows nothing about opentelemetry or --export-traces.

Thus converting to a discussion. If I had to guess, your subprocess.run(f"python3 app.py ...") probably runs a different Python environment than what you have your dependencies installed in.