HDDS-1090. Add a recipe to the ozone docs about using Spark, OzoneFS, and K8s.

Contributed by Elek, Marton.

hadoop-hdds/docs/content/SparkOzoneFSK8S.md

@@ -0,0 +1,184 @@
+---
+title: Spark in Kubernetes with OzoneFS
+menu:
+   main:
+      parent: Recipes
+---
+<!---
+  Licensed to the Apache Software Foundation (ASF) under one or more
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+  The ASF licenses this file to You under the Apache License, Version 2.0
+  (the "License"); you may not use this file except in compliance with
+  the License.  You may obtain a copy of the License at
+
+      http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+-->
+
+Using Ozone from Apache Spark
+===
+
+This recipe shows how Ozone object store can be used from Spark using:
+
+ - OzoneFS (Hadoop compatible file system)
+ - Hadoop 2.7 (included in the Spark distribution)
+ - Kubernetes Spark scheduler
+ - Local spark client
+
+
+## Requirements
+
+Download latest Spark and Ozone distribution and extract them. This method is 
+tested with the `spark-2.4.0-bin-hadoop2.7` distribution.
+
+You also need the following:
+
+ * A container repository to push and pull the spark+ozone images. (In this recipe we will use the dockerhub)
+ * A repo/name for the custom containers (in this recipe _myrepo/ozone-spark_)
+ * A dedicated namespace in kubernetes (we use _yournamespace_ in this recipe)
+
+## Create the docker image for drivers
+
+### Create the base Spark driver/executor image
+
+First of all create a docker image with the Spark image creator. 
+Execute the following from the Spark distribution
+
+```
+./bin/docker-image-tool.sh -r myrepo -t 2.4.0 build
+```
+
+_Note_: if you use Minikube add the `-m` flag to use the docker daemon of the Minikube image:
+
+```
+./bin/docker-image-tool.sh -m -r myrepo -t 2.4.0 build
+```
+
+`./bin/docker-image-tool.sh` is an official Spark tool to create container images and this step will create multiple Spark container images with the name _myrepo/spark_. The first container will be used as a base container in the following steps.
+
+### Customize the docker image
+
+Create a new directory for customizing the created docker image.
+
+Copy the `ozone-site.xml` from the cluster:
+
+```
+kubectl cp om-0:/opt/hadoop/etc/hadoop/ozone-site.xml .
+```
+
+And create a custom `core-site.xml`:
+
+```
+<configuration>
+    <property>
+        <name>fs.o3fs.impl</name>
+        <value>org.apache.hadoop.fs.ozone.OzoneFileSystem</value>
+    </property>
+</configuration>
+```
+
+Copy the `ozonefs.jar` file from an ozone distribution (__use the legacy version!__)
+
+```
+kubectl cp om-0:/opt/hadoop/share/ozone/lib/hadoop-ozone-filesystem-lib-legacy-0.4.0-SNAPSHOT.jar .
+```
+
+
+Create a new Dockerfile and build the image:
+```
+FROM myrepo/spark:2.4.0
+ADD core-site.xml /opt/hadoop/conf/core-site.xml
+ADD ozone-site.xml /opt/hadoop/conf/ozone-site.xml
+ENV HADOOP_CONF_DIR=/opt/hadoop/conf
+ENV SPARK_EXTRA_CLASSPATH=/opt/hadoop/conf
+ADD hadoop-ozone-filesystem-lib-legacy-0.4.0-SNAPSHOT.jar /opt/hadoop-ozone-filesystem-lib-legacy.jar
+```
+
+```
+docker build -t myrepo/spark-ozone
+```
+
+For remote kubernetes cluster you may need to push it:
+
+```
+docker push myrepo/spark-ozone
+```
+
+## Create a bucket and identify the ozonefs path
+
+Download any text file and put it to the `/tmp/alice.txt` first.
+
+```
+kubectl port-forward s3g-0 9878:9878
+aws s3api --endpoint http://localhost:9878 create-bucket --bucket=test
+aws s3api --endpoint http://localhost:9878 put-object --bucket test --key alice.txt --body /tmp/alice.txt
+kubectl exec -it scm-0 ozone sh bucket path test
+```
+
+The output of the last command is something like this:
+
+```
+Volume name for S3Bucket is : s3asdlkjqiskjdsks
+Ozone FileSystem Uri is : o3fs://test.s3asdlkjqiskjdsks
+```
+
+Write down the ozone filesystem uri as it should be used with the spark-submit command.
+
+## Create service account to use
+
+```
+kubectl create serviceaccount spark -n yournamespace
+kubectl create clusterrolebinding spark-role --clusterrole=edit --serviceaccount=poc:yournamespace --namespace=yournamespace
+```
+## Execute the job
+
+Execute the following spar-submit command, but change at least the following values:
+
+ * the kubernetes master url (you can check your ~/.kube/config to find the actual value)
+ * the kubernetes namespace (yournamespace in this example)
+ * serviceAccountName (you can use the _spark_ value if you folllowed the previous steps)
+ * container.image (in this example this is myrepo/spark-ozone. This is pushed to the registry in the previous steps)
+ * location of the input file (o3fs://...), use the string which is identified earlier with the `ozone sh bucket path` command
+
+```
+bin/spark-submit \
+    --master k8s://https://kubernetes:6443 \
+    --deploy-mode cluster \
+    --name spark-word-count \
+    --class org.apache.spark.examples.JavaWordCount \
+    --conf spark.executor.instances=1 \
+    --conf spark.kubernetes.namespace=yournamespace \
+    --conf spark.kubernetes.authenticate.driver.serviceAccountName=spark \
+    --conf spark.kubernetes.container.image=myrepo/spark-ozone \
+    --conf spark.kubernetes.container.image.pullPolicy=Always \
+    --jars /opt/hadoop-ozone-filesystem-lib-legacy.jar \
+    local:///opt/spark/examples/jars/spark-examples_2.11-2.4.0.jar \
+    o3fs://bucket.volume/alice.txt
+```
+
+Check the available `spark-word-count-...` pods with `kubectl get pod`
+
+Check the output of the calculation with `kubectl logs spark-word-count-1549973913699-driver`
+
+You should see the output of the wordcount job. For example:
+
+```
+...
+name: 8
+William: 3
+this,': 1
+SOUP!': 1
+`Silence: 1
+`Mine: 1
+ordered.: 1
+considering: 3
+muttering: 3
+candle: 2
+...
+```