Fix xarray earthkit attribute size

Author: sandorkertesz

src/earthkit/data/field/grib/metadata.py

@@ -193,14 +193,16 @@ def step_timedelta(self):
             v = self.get("step", None)
         return to_timedelta(v)
 
-    def message(self):
+    def message(self, deflate=False):
         r"""Return a buffer containing the encoded message.
 
         Returns
         -------
         bytes
         """
-        return self.handle.get_buffer()
+        if deflate:
+            return self._handle.deflate().get_buffer()
+        return self._handle.get_buffer()
 
     def as_namespace(self, namespace):
         return self.handle.as_namespace(namespace)

src/earthkit/data/xr_engine/builder.py

@@ -86,7 +86,7 @@ def build(self, add_earthkit_attrs=True):
         if add_earthkit_attrs:
             f = self.tensor.source[0]
             try:
-                md = f.message()
+                md = f._get_grib().message(deflate=True)
             except Exception:
                 md = ""