From 04ffa6c4ba7fec3ec1c11e0a0b6a51e0a9b15545 Mon Sep 17 00:00:00 2001
From: dcherian <deepak@cherian.net>
Date: Wed, 6 May 2020 13:36:15 -0600
Subject: [PATCH] Propagate attributes for index variables.

---
 xarray/core/parallel.py   | 3 +++
 xarray/tests/test_dask.py | 4 ++++
 2 files changed, 7 insertions(+)

diff --git a/xarray/core/parallel.py b/xarray/core/parallel.py
index c2b09c119ad..7ae5c624ea2 100644
--- a/xarray/core/parallel.py
+++ b/xarray/core/parallel.py
@@ -541,6 +541,9 @@ def map_blocks(
         hlg.layers[gname_l] = layer
 
     result = Dataset(coords=indexes, attrs=template.attrs)
+    for index in result.indexes:
+        result[index].attrs = template[index].attrs
+
     for name, gname_l in var_key_map.items():
         dims = template[name].dims
         var_chunks = []
diff --git a/xarray/tests/test_dask.py b/xarray/tests/test_dask.py
index 63234a5319e..ba51c034296 100644
--- a/xarray/tests/test_dask.py
+++ b/xarray/tests/test_dask.py
@@ -972,6 +972,7 @@ def make_da():
         coords={"x": np.arange(10), "y": np.arange(100, 120)},
         name="a",
     ).chunk({"x": 4, "y": 5})
+    da.x.attrs["long_name"] = "x"
     da.attrs["test"] = "test"
     da.coords["c2"] = 0.5
     da.coords["ndcoord"] = da.x * 2
@@ -995,6 +996,9 @@ def make_ds():
     map_ds.attrs["test"] = "test"
     map_ds.coords["xx"] = map_ds["a"] * map_ds.y
 
+    map_ds.x.attrs["long_name"] = "x"
+    map_ds.y.attrs["long_name"] = "y"
+
     return map_ds