Use APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE env var in _is_attach_enabled

[jeremydvoss]

Update _is_attach_enabled() to check the new
APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE environment variable set by the RP integration agent (sitecustomize.py). When the env var is present, attach is only considered enabled if it is set to IntegratedAuto AND the existing per-RP logic (Functions, App Service, AKS) is satisfied. When the env var is absent, the function falls back to legacy detection (path-based for App Service, env-var-based for Functions/AKS).

This resolves false positives where the agent path exists but auto-instrumentation backed off or failed to attach.

Description

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[Copilot]

Pull request overview

This PR updates attach detection in azure-monitor-opentelemetry-exporter by introducing support for the APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE environment variable, aiming to reduce false positives from legacy attach heuristics.

Changes:

• Added _APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE constant and updated _is_attach_enabled() to consult it before legacy detection.
• Added unit tests covering attach-type scenarios across App Service, Functions, and AKS.
• Documented the change in the package changelog.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_utils.py	Adds attach-type env-var check to _is_attach_enabled(), before falling back to legacy heuristics.
sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_constants.py	Introduces constant for APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE.
sdk/monitor/azure-monitor-opentelemetry-exporter/tests/test_utils.py	Adds tests for attach enablement behavior when APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE is set and when it is absent.
sdk/monitor/azure-monitor-opentelemetry-exporter/CHANGELOG.md	Adds changelog entry describing the new attach detection behavior.

Comments suppressed due to low confidence (1)

sdk/monitor/azure-monitor-opentelemetry-exporter/azure/monitor/opentelemetry/exporter/_utils.py:86

• _is_attach_enabled short-circuits to True when APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE == "IntegratedAuto", but the in-code comment (and PR description) says it should also satisfy the existing per-RP attach checks (Functions/App Service/AKS). As written, it bypasses checks like Functions PYTHON_APPLICATIONINSIGHTS_ENABLE_TELEMETRY, App Service agent path, and AKS AKS_ARM_NAMESPACE_ID, which can reintroduce false positives. Either apply the per-RP logic before returning True (when attach_type is IntegratedAuto) or update the comment/contract to match the intended authoritative behavior.

def _is_attach_enabled():
    attach_type = environ.get(_APPLICATIONINSIGHTS_PYTHON_ATTACHTYPE)
    if attach_type is not None:
        # If the env var is set, attach is only enabled if the value is
        # "IntegratedAuto" AND the existing per-RP logic is satisfied.
        if attach_type == "IntegratedAuto":
            return True
        return False
    # Fallback to legacy logic when the env var is not set
    if _is_on_functions():
        return environ.get(_PYTHON_APPLICATIONINSIGHTS_ENABLE_TELEMETRY) == "true"
    if _is_on_app_service():
        return isdir("/agents/python/")
    if _is_on_aks():
        return _AKS_ARM_NAMESPACE_ID in environ
    return False

[rads-1996]

LGTM