[core] add deprecation warning for DATADOG_ environment variables

Author: Emanuele Palazzetti

ddtrace/utils/formats.py

@@ -1,5 +1,7 @@
 import os
 
+from .deprecation import deprecation
+
 
 def get_env(integration, variable, default=None):
     """Retrieves environment variables value for the given integration. It must be used
@@ -15,9 +17,12 @@ def get_env(integration, variable, default=None):
     legacy_env = 'DATADOG_{}'.format(key)
     env = 'DD_{}'.format(key)
 
-    # [Backward compatibility]: `DATADOG_` variables should be supported;
-    # add a deprecation warning later if it's used, so that we can drop the key
-    # in newer releases.
+    # [Backward compatibility]: `DATADOG_` variables are deprecated
+    deprecation(
+        name='DATADOG_',
+        message='Use `DD_` prefix instead',
+        version='1.0.0',
+    )
     value = os.getenv(env) or os.getenv(legacy_env)
     return value if value else default
 

tests/test_utils.py

@@ -37,10 +37,15 @@ def test_get_env_found(self):
 
     def test_get_env_found_legacy(self):
         # ensure `get_env` returns a value if legacy environment variables
-        # are used
-        os.environ['DATADOG_REQUESTS_DISTRIBUTED_TRACING'] = '1'
-        value = get_env('requests', 'distributed_tracing')
-        eq_(value, '1')
+        # are used, raising a Deprecation warning
+        with warnings.catch_warnings(record=True) as w:
+            warnings.simplefilter('always')
+            os.environ['DATADOG_REQUESTS_DISTRIBUTED_TRACING'] = '1'
+            value = get_env('requests', 'distributed_tracing')
+            eq_(value, '1')
+            ok_(len(w) == 1)
+            ok_(issubclass(w[-1].category, DeprecationWarning))
+            ok_('Use `DD_` prefix instead' in str(w[-1].message))
 
     def test_get_env_key_priority(self):
         # ensure `get_env` use `DD_` with highest priority