[tune] horovod trainable (#10304)

doc/source/conf.py

@@ -36,6 +36,8 @@ MOCK_MODULES = [
     "blist",
     "gym",
     "gym.spaces",
+    "horovod",
+    "horovod.ray",
     "kubernetes",
     "psutil",
     "ray._raylet",

doc/source/tune/api_docs/integration.rst

@@ -43,6 +43,14 @@ Torch (tune.integration.torch)
 
 .. autofunction:: ray.tune.integration.torch.is_distributed_trainable
 
+
+.. _tune-integration-horovod:
+
+Horovod (tune.integration.horovod)
+----------------------------------
+
+.. autofunction:: ray.tune.integration.horovod.DistributedTrainableCreator
+
 .. _tune-integration-wandb:
 
 Weights and Biases (tune.integration.wandb)

doc/source/tune/examples/horovod_simple.rst

@@ -0,0 +1,6 @@
+:orphan:
+
+horovod_simple
+~~~~~~~~~~~~~~
+
+.. literalinclude:: /../../python/ray/tune/examples/horovod_simple.py

doc/source/tune/examples/index.rst

@@ -35,6 +35,10 @@ Tensorflow/Keras Examples
 - :doc:`/tune/examples/pbt_memnn_example`: Example of training a Memory NN on bAbI with Keras using PBT.
 - :doc:`/tune/examples/tf_mnist_example`: Converts the Advanced TF2.0 MNIST example to use Tune with the Trainable. This uses `tf.function`. Original code from tensorflow: https://www.tensorflow.org/tutorials/quickstart/advanced
 
+Horovod Example
+~~~~~~~~~~~~~~~
+- :doc:`/tune/examples/horovod_simple`: Leverages the :ref:`Horovod-Tune <tune-integration-horovod>` integration to launch a distributed training + tuning job.
+
 
 PyTorch Examples
 ~~~~~~~~~~~~~~~~