Remove customDimensions items from Application Insights when using opencensus-python

Question

In the documentation on how to use opencensus-python to submit traces to Azure Application Insights, it's spelled out how to add additional information to the customDimensions field. That is,

import logging

from opencensus.ext.azure.log_exporter import AzureLogHandler

logger = logging.getLogger(__name__)
logger.addHandler(AzureLogHandler(
    connection_string='InstrumentationKey=00000000-0000-0000-0000-000000000000')
)

logger.error('blooh')
logger.error('blooh2', extra={'custom_dimensions': {'woot': 42}})

becomes

in the Application Insights UI.

That's all well and good, but what is the intended way to remove the items from customDimensions that are included by default; i.e. things like fileName and process?

Answer 1

By inspection of the source code, the properties do seem rather hard to avoid to create, but it is possible to remove them by post-processing the envelope:

import logging

from opencensus.ext.azure.log_exporter import AzureLogHandler

custom_dimensions = {'foo': 'bar'}

def remove_items(envelope):
    envelope.data.baseData.properties = custom_dimensions
    return True

logger = logging.getLogger(__name__)
handler = AzureLogHandler(connection_string='InstrumentationKey=00000000-0000-0000-0000-000000000000')
handler.add_telemetry_processor(remove_items)
logger.addHandler(handler)
logger.error('blooh')

This is tested and works in opencensus-ext-azure version 1.0.5.

Notice also that with this approarch, it is no longer necessary to specify the extra when logging.