[Utility] add env_float utility into ray._private.ray_constants (r…

…ay-project#47117)

The current codebase includes `env_bool` and `env_integer` functions
that directly convert environment variable strings into their respective
types. To extend this functionality, we also need an `env_float`
function to safely convert strings representing floating-point numbers
into the `float` type."

Signed-off-by: Hongpeng Guo <hpguo@anyscale.com>

python/ray/_private/ray_constants.py

@@ -23,6 +23,21 @@ def env_integer(key, default):
     return default
 
 
+def env_float(key, default):
+    if key in os.environ:
+        value = os.environ[key]
+        try:
+            return float(value)
+        except ValueError:
+            logger.debug(
+                f"Found {key} in environment, but value must "
+                f"be a float. Got: {value}. Returning "
+                f"provided default {default}."
+            )
+            return default
+    return default
+
+
 def env_bool(key, default):
     if key in os.environ:
         return (