Describe your environment

OS: macOS / Linux
Python version: 3.10 / 3.11 / 3.12
SDK version: main
API version: main

What happened?

According to the OpenTelemetry Metrics Specification - View (https://opentelemetry.io/docs/specs/otel/metrics/sdk/#view):

"If name is provided, the View MUST match at most one instrument. If instrument_name contains wildcard characters (*, ?, [seq], [!seq]), name MUST NOT be provided."

In opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/view.py, View.__init__ checks for wildcard characters when a custom name is provided:

if name is not None and instrument_name is not None and ("*" in instrument_name or "?" in instrument_name):
raise Exception(f"View {name} declared with wildcard characters in instrument_name")

However, instrument matching is performed using fnmatch.fnmatchcase() (line 153), which supports character sequence wildcards such as [seq] and [!seq] (e.g. http_[0-9]).

Because View.__init__ only checks for * and ?, passing a wildcard pattern containing [ or ] (e.g. instrument_name="http_[0-9]") alongside a custom name (e.g. name="custom_name") fails to raise an Exception. This allows a single renamed View stream to match multiple instruments, violating the specification constraint.

Steps to Reproduce

from opentelemetry.sdk.metrics.view import View

Should raise Exception because 'http_[0-9]' contains fnmatch wildcard '[', but currently succeeds:

v = View(name="custom_name", instrument_name="http_[0-9]")

Expected Result

View(name="custom_name", instrument_name="http_[0-9]") should raise an Exception during initialization, matching the behavior when '*' or '?' is used.

Actual Result

View initializes without error and matches multiple instruments (e.g., http_1, http_2), renaming all of them to custom_name.

Additional context

Suggested fix in opentelemetry-sdk/src/opentelemetry/sdk/metrics/_internal/view.py:

if name is not None and instrument_name is not None and any(c in instrument_name for c in "*?["):
raise Exception(f"View {name} declared with wildcard characters in instrument_name")

Would you like to implement a fix?

Yes