[carriers] add env carrier

opentelemetry-api/src/opentelemetry/propagators/envcarrier.py

@@ -0,0 +1,60 @@
+import os
+import typing
+from opentelemetry.propagators.textmap import Getter, Setter
+
+class EnvironmentGetter(Getter[dict]):
+    """This class decorates Getter to enable extracting from context and baggage
+    from environment variables.
+    """
+
+    KEY_MAPPING = {
+        "TRACEPARENT": "traceparent",
+        "TRACESTATE": "tracestate",
+        "BAGGAGE": "baggage"
+    }
+
+    def __init__(self):
+        self.env_copy = dict(os.environ)
+        self.carrier = {}
+
+        for env_key, env_value in self.env_copy.items():
+            if env_key in self.KEY_MAPPING:
+                self.carrier[self.KEY_MAPPING[env_key]] = env_value
+            else:
+                self.carrier[env_key] = env_value
+
+    def get(self, carrier: dict, key: str) -> typing.Optional[typing.List[str]]:
+        """Get a value from the carrier for the given key"""
+        val = self.carrier.get(key, None)
+        if val is None:
+            return None
+        if isinstance(val, typing.Iterable) and not isinstance(val, str):
+            return list(val)
+        return [val]
+
+    def keys(self, carrier: dict) -> typing.List[str]:
+        """Get all keys from the carrier"""
+        return list(self.carrier.keys())
+
+class EnvironmentSetter(Setter[dict]):
+    """This class decorates Setter to enable setting context and baggage
+    to environment variables.
+    """
+
+    KEY_MAPPING = {
+        "TRACEPARENT": "traceparent",
+        "TRACESTATE": "tracestate",
+        "BAGGAGE": "baggage"
+    }
+
+    def set(self, carrier: typing.Optional[dict], key: str, value: str) -> None:
+        """Set a value in the environment for the given key.
+
+        Args:
+            carrier: Not used for environment setter, but kept for interface compatibility
+            key: The key to set
+            value: The value to set
+        """
+        env_key = self.KEY_MAPPING.get(key, key.upper())
+
+        os.environ[env_key] = value