sdk: a bytes attribute crashes the console span exporter

[mauriciovasquezbernal]

The current logic to check attributes' types admits the bytes in, it creates problem in the exporters that don't perform type check.

Reproducer:

from opentelemetry import trace
from opentelemetry.sdk.trace import TracerProvider
from opentelemetry.sdk.trace.export import (
    SimpleExportSpanProcessor,
    ConsoleSpanExporter,
)

trace.set_tracer_provider(TracerProvider())
trace.get_tracer_provider().add_span_processor(
  SimpleExportSpanProcessor(ConsoleSpanExporter())
)

tracer = trace.get_tracer(__name__)

with tracer.start_as_current_span("foo") as foo:
  foo.set_attribute("willcrash", b"hi")
  print("Hello world from OpenTelemetry Python!")

I did a quick look and it happens because bytes is a Sequence, and each element inside is an integer.

I don't know if the we should update the logic to reject that kind of attributes or update the exporters to be able to accept them.

[sethmaxwl]

I can take this

[codeboten]

Thanks! Assigned.

[sethmaxwl]

Would decoding anything of the type bytes before setting the attribute be an acceptable fix here?

[aabmass]

Linking my comment from the PR here: #775 (comment)

FWIW the OTLP proto doesn't include any bytes type: https://github.com/open-telemetry/opentelemetry-proto/blob/b54688569186e0b862bf7462a983ccf2c50c0547/opentelemetry/proto/common/v1/common.proto#L26-L48

[codeboten]

fixed by #775