261 lines
9.8 KiB
Markdown
261 lines
9.8 KiB
Markdown
---
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id: tutorial-batch-hadoop
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title: "Tutorial: Load batch data using Apache Hadoop"
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sidebar_label: "Load from Apache Hadoop"
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---
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<!--
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~ Licensed to the Apache Software Foundation (ASF) under one
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~ or more contributor license agreements. See the NOTICE file
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~ "License"); you may not use this file except in compliance
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~ under the License.
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This tutorial shows you how to load data files into Apache Druid using a remote Hadoop cluster.
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For this tutorial, we'll assume that you've already completed the previous
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[batch ingestion tutorial](tutorial-batch.html) using Druid's native batch ingestion system and are using the
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`micro-quickstart` single-machine configuration as described in the [quickstart](index.html).
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## Install Docker
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This tutorial requires [Docker](https://docs.docker.com/install/) to be installed on the tutorial machine.
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Once the Docker install is complete, please proceed to the next steps in the tutorial.
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## Build the Hadoop docker image
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For this tutorial, we've provided a Dockerfile for a Hadoop 2.8.5 cluster, which we'll use to run the batch indexing task.
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This Dockerfile and related files are located at `quickstart/tutorial/hadoop/docker`.
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From the apache-druid-apache-druid-0.21.1 package root, run the following commands to build a Docker image named "druid-hadoop-demo" with version tag "2.8.5":
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```bash
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cd quickstart/tutorial/hadoop/docker
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docker build -t druid-hadoop-demo:2.8.5 .
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```
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This will start building the Hadoop image. Once the image build is done, you should see the message `Successfully tagged druid-hadoop-demo:2.8.5` printed to the console.
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## Setup the Hadoop docker cluster
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### Create temporary shared directory
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We'll need a shared folder between the host and the Hadoop container for transferring some files.
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Let's create some folders under `/tmp`, we will use these later when starting the Hadoop container:
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```bash
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mkdir -p /tmp/shared
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mkdir -p /tmp/shared/hadoop_xml
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```
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### Configure /etc/hosts
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On the host machine, add the following entry to `/etc/hosts`:
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```
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127.0.0.1 druid-hadoop-demo
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```
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### Start the Hadoop container
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Once the `/tmp/shared` folder has been created and the `etc/hosts` entry has been added, run the following command to start the Hadoop container.
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```bash
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docker run -it -h druid-hadoop-demo --name druid-hadoop-demo -p 2049:2049 -p 2122:2122 -p 8020:8020 -p 8021:8021 -p 8030:8030 -p 8031:8031 -p 8032:8032 -p 8033:8033 -p 8040:8040 -p 8042:8042 -p 8088:8088 -p 8443:8443 -p 9000:9000 -p 10020:10020 -p 19888:19888 -p 34455:34455 -p 49707:49707 -p 50010:50010 -p 50020:50020 -p 50030:50030 -p 50060:50060 -p 50070:50070 -p 50075:50075 -p 50090:50090 -p 51111:51111 -v /tmp/shared:/shared druid-hadoop-demo:2.8.5 /etc/bootstrap.sh -bash
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```
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Once the container is started, your terminal will attach to a bash shell running inside the container:
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```bash
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Starting sshd: [ OK ]
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18/07/26 17:27:15 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
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Starting namenodes on [druid-hadoop-demo]
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druid-hadoop-demo: starting namenode, logging to /usr/local/hadoop/logs/hadoop-root-namenode-druid-hadoop-demo.out
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localhost: starting datanode, logging to /usr/local/hadoop/logs/hadoop-root-datanode-druid-hadoop-demo.out
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Starting secondary namenodes [0.0.0.0]
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0.0.0.0: starting secondarynamenode, logging to /usr/local/hadoop/logs/hadoop-root-secondarynamenode-druid-hadoop-demo.out
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18/07/26 17:27:31 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
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starting yarn daemons
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starting resourcemanager, logging to /usr/local/hadoop/logs/yarn--resourcemanager-druid-hadoop-demo.out
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localhost: starting nodemanager, logging to /usr/local/hadoop/logs/yarn-root-nodemanager-druid-hadoop-demo.out
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starting historyserver, logging to /usr/local/hadoop/logs/mapred--historyserver-druid-hadoop-demo.out
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bash-4.1#
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```
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The `Unable to load native-hadoop library for your platform... using builtin-java classes where applicable` warning messages can be safely ignored.
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#### Accessing the Hadoop container shell
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To open another shell to the Hadoop container, run the following command:
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```
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docker exec -it druid-hadoop-demo bash
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```
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### Copy input data to the Hadoop container
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From the apache-druid-apache-druid-0.21.1 package root on the host, copy the `quickstart/tutorial/wikiticker-2015-09-12-sampled.json.gz` sample data to the shared folder:
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```bash
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cp quickstart/tutorial/wikiticker-2015-09-12-sampled.json.gz /tmp/shared/wikiticker-2015-09-12-sampled.json.gz
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```
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### Setup HDFS directories
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In the Hadoop container's shell, run the following commands to setup the HDFS directories needed by this tutorial and copy the input data to HDFS.
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```bash
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cd /usr/local/hadoop/bin
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./hdfs dfs -mkdir /druid
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./hdfs dfs -mkdir /druid/segments
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./hdfs dfs -mkdir /quickstart
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./hdfs dfs -chmod 777 /druid
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./hdfs dfs -chmod 777 /druid/segments
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./hdfs dfs -chmod 777 /quickstart
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./hdfs dfs -chmod -R 777 /tmp
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./hdfs dfs -chmod -R 777 /user
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./hdfs dfs -put /shared/wikiticker-2015-09-12-sampled.json.gz /quickstart/wikiticker-2015-09-12-sampled.json.gz
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```
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If you encounter namenode errors when running this command, the Hadoop container may not be finished initializing. When this occurs, wait a couple of minutes and retry the commands.
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## Configure Druid to use Hadoop
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Some additional steps are needed to configure the Druid cluster for Hadoop batch indexing.
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### Copy Hadoop configuration to Druid classpath
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From the Hadoop container's shell, run the following command to copy the Hadoop .xml configuration files to the shared folder:
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```bash
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cp /usr/local/hadoop/etc/hadoop/*.xml /shared/hadoop_xml
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```
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From the host machine, run the following, where {PATH_TO_DRUID} is replaced by the path to the Druid package.
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```bash
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mkdir -p {PATH_TO_DRUID}/conf/druid/single-server/micro-quickstart/_common/hadoop-xml
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cp /tmp/shared/hadoop_xml/*.xml {PATH_TO_DRUID}/conf/druid/single-server/micro-quickstart/_common/hadoop-xml/
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```
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### Update Druid segment and log storage
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In your favorite text editor, open `conf/druid/single-server/micro-quickstart/_common/common.runtime.properties`, and make the following edits:
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#### Disable local deep storage and enable HDFS deep storage
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```
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#
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# Deep storage
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#
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# For local disk (only viable in a cluster if this is a network mount):
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#druid.storage.type=local
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#druid.storage.storageDirectory=var/druid/segments
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# For HDFS:
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druid.storage.type=hdfs
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druid.storage.storageDirectory=/druid/segments
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```
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#### Disable local log storage and enable HDFS log storage
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```
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#
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# Indexing service logs
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#
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# For local disk (only viable in a cluster if this is a network mount):
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#druid.indexer.logs.type=file
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#druid.indexer.logs.directory=var/druid/indexing-logs
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# For HDFS:
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druid.indexer.logs.type=hdfs
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druid.indexer.logs.directory=/druid/indexing-logs
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```
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### Restart Druid cluster
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Once the Hadoop .xml files have been copied to the Druid cluster and the segment/log storage configuration has been updated to use HDFS, the Druid cluster needs to be restarted for the new configurations to take effect.
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If the cluster is still running, CTRL-C to terminate the `bin/start-micro-quickstart` script, and re-run it to bring the Druid services back up.
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## Load batch data
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We've included a sample of Wikipedia edits from September 12, 2015 to get you started.
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To load this data into Druid, you can submit an *ingestion task* pointing to the file. We've included
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a task that loads the `wikiticker-2015-09-12-sampled.json.gz` file included in the archive.
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Let's submit the `wikipedia-index-hadoop-.json` task:
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```bash
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bin/post-index-task --file quickstart/tutorial/wikipedia-index-hadoop.json --url http://localhost:8081
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```
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## Querying your data
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After the data load is complete, please follow the [query tutorial](../tutorials/tutorial-query.md) to run some example queries on the newly loaded data.
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## Cleanup
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This tutorial is only meant to be used together with the [query tutorial](../tutorials/tutorial-query.md).
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If you wish to go through any of the other tutorials, you will need to:
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* Shut down the cluster and reset the cluster state by removing the contents of the `var` directory under the druid package.
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* Revert the deep storage and task storage config back to local types in `conf/druid/single-server/micro-quickstart/_common/common.runtime.properties`
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* Restart the cluster
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This is necessary because the other ingestion tutorials will write to the same "wikipedia" datasource, and later tutorials expect the cluster to use local deep storage.
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Example reverted config:
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```
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#
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# Deep storage
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#
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# For local disk (only viable in a cluster if this is a network mount):
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druid.storage.type=local
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druid.storage.storageDirectory=var/druid/segments
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# For HDFS:
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#druid.storage.type=hdfs
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#druid.storage.storageDirectory=/druid/segments
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#
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# Indexing service logs
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#
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# For local disk (only viable in a cluster if this is a network mount):
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druid.indexer.logs.type=file
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druid.indexer.logs.directory=var/druid/indexing-logs
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# For HDFS:
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#druid.indexer.logs.type=hdfs
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#druid.indexer.logs.directory=/druid/indexing-logs
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```
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## Further reading
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For more information on loading batch data with Hadoop, please see [the Hadoop batch ingestion documentation](../ingestion/hadoop.md).
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