tracer.add_attribute_to_current_span from wsgi Middleware

[ctaggart]

Is it possible to tracer.add_attribute_to_current_span within a Flask middleware?

I set up a basic middleware:

from werkzeug.wrappers import Request
from opencensus.trace import execution_context

class IDMiddleware:
    def __init__(self, app):
        self.app = app
    def __call__(self, environ, start_response):
        request = Request(environ)
        tracer = execution_context.get_opencensus_tracer()
        tracer.add_attribute_to_current_span("id", 551212)
        return self.app(environ, start_response)

I registered both the FlaskMiddleware and this middleware:

middleware = FlaskMiddleware(app, sampler=sampler, exporter=exporter)
app.wsgi_app = IDMiddleware(app.wsgi_app)

But it errors with:

  File "/home/cameron/.local/share/virtualenvs/sark-o0ke7yP6/lib/python3.7/site-packages/opencensus/trace/tracer.py", line 132, in add_attribute_to_current_span
    attribute_key, attribute_value)
  File "/home/cameron/.local/share/virtualenvs/sark-o0ke7yP6/lib/python3.7/site-packages/opencensus/trace/tracers/context_tracer.py", line 147, in add_attribute_to_current_span
    current_span.add_attribute(attribute_key, attribute_value)
AttributeError: 'NoneType' object has no attribute 'add_attribute'

I'm guessing it is because the FlaskMiddleware isn't wsgi middleware and instead registered with these three callbacks: https://github.com/census-instrumentation/opencensus-python/blob/22c1a285d8234d3ac5414c1e7be6901b772681aa/contrib/opencensus-ext-flask/opencensus/ext/flask/flask_middleware.py#L122-L125

I couldn't figure out how to to control the order of middleware by turning it into wsgi middleware or registering another set of callbacks. Looks like #368 is related.

[tomas223]

Hi. I'm having the same issue. Is there any solution workaround for this?

[allanlw]

I think this package is dead, and you need to switch to open telemetry.

On Thu, Jun 3, 2021, at 7:41 AM, Tomas Hornak wrote:

Hi. I'm having the same issue. Is there any solution workaround for this?

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[tomas223]

@allanlw thank you for response. That is unfortunate, because Azure, where I'm using it still recommends Opencensus :/