Semantic conventions for exceptions

Existing instrumentations that record exceptions as span events:

• SHOULD introduce an environment variable OTEL_SEMCONV_EXCEPTION_SIGNAL_OPT_IN supporting the following values:
  • logs - emit exceptions as logs only.
  • logs/dup - emit both span events and logs, allowing for a phased rollout.
  • The default behavior (in the absence of one of these values) is to continue emitting exceptions as span events (existing behavior).
• SHOULD maintain (security patching at a minimum) their existing major version for at least six months after it starts emitting both sets of conventions.
• MAY drop the environment variable in their next major version and emit exceptions as logs only.

Even after instrumentations start emitting exceptions only as logs, users will still have the option to route those to span events at the SDK layer.