INNER CODE UNIT · Python

ResponseHeaderLabel

stephenhillier/starlette_exporter · starlette_exporter/labels.py:7

class ResponseHeaderLabel:
    """ResponseHeaderLabel is a special class that allows populating a label
    value based on response headers. starlette_exporter will recognize that this
    should not be called until response headers are written."""

    def __init__(
        self, key: str, allowed_values: Optional[Iterable] = None, default: str = ""
    ) -> None:
        self.key = key.lower()
        self.default = default
        self.allowed_values = allowed_values

    def __call__(self, headers: Dict) -> Any:
        v = headers.get(self.key, self.default)
        if self.allowed_values is not None and v not in self.allowed_values:
            return self.default
        return v

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