druid/docs/content/Booting-a-production-cluster.md

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Booting a Druid Cluster

Loading Your Data and All About Queries contain recipes to boot a small druid cluster on localhost. However, when it's time to run a more realistic setup—for production or just for testing production—you'll want to find a way to start the cluster on multiple hosts. This document describes two different ways to do this: manually, or as a cloud service via Apache Whirr.

Manually Booting a Druid Cluster

You can provision individual servers, loading Druid onto each machine (or building it) and setting the required configuration for each type of node. You'll also have to set up required external dependencies. Then you'll have to start each node. This process is outlined in Tutorial: The Druid Cluster.

Apache Whirr

Apache Whirr is a set of libraries for launching cloud services. For Druid, Whirr serves as an easy way to launch a cluster in Amazon AWS by using simple commands and configuration files (called recipes).

NOTE: Whirr will install Druid 0.5.x. At this time Whirr can launch Druid 0.5.x only, but in the near future will support Druid 0.6.x. You can download and install your own copy of Druid 0.5.x here.

You'll need an AWS account, and an EC2 key pair from that account so that Whirr can connect to the cloud via the EC2 API. If you haven't generated a key pair, see the AWS documentation or see this Whirr FAQ.

Installing Whirr

You must use a version of Whirr that includes and supports a Druid recipe. You can do it so in one of two ways:

Build the Following Version of Whirr

Clone the code from https://github.com/rjurney/whirr/tree/trunk and build Whirr:

git clone git@github.com:rjurney/whirr.git
cd whirr
git checkout trunk
mvn clean install -Dmaven.test.failure.ignore=true

Build the Latest Version of Whirr

Clone the code from the Whirr repository:

git clone git://git.apache.org/whirr.git

Then run mvn install from the root directory.

Configure Whirr

The Whirr recipe for Druid is the configuration file $WHIRR_HOME/recipies/druid.properties. You can edit this file to suit your needs -- it is annotated and self-explanatory. Here are some hints about that file:

• Set whirr.location-id to a specific AWS region (e.g., us-east-1) if desired, else one will be chosen for you.
• You can choose the hardware used with whirr.hardware-id to a specific AWS region (e.g., m1.large). If you don't choose an image via whirr.image-id (image must be compatible with hardware), you'll get plain vanilla Linux.
• SSH keys (not password protected) must exist for the local user. If they are in the default locations, ${sys:user.home}/.ssh/id_rsa and ${sys:user.home}/.ssh/id_rsa.pub, Whirr will find them. Otherwise, you'll have to specify them with whirr.private-key-file and whirr.public-key-file.
• Be sure to specify the absolute path of the Druid realtime spec file realtime.spec in whirr.druid.realtime.spec.path.
• Two Druid cluster templates (see whirr.instance-templates) are provided: a small cluster running on a single EC2 instance, and a larger cluster running on multiple instances. The first is a good test case to start with.

The following AWS information must be set in druid.properties, as environment variables, or in the file $WHIRR_HOME/conf/credentials:

PROVIDER=aws-ec2
IDENTITY=<aws-id-key>
CREDENTIAL=<aws-private-key>

How to get the IDENTITY and CREDENTIAL keys is discussed above.

Start a Test Cluster With Whirr

Run the following command:

% $WHIRR_HOME/bin/whirr launch-cluster --config $WHIRR_HOME/recipes/druid.properties

If Whirr starts without an errors, you should see the following message:

Running on provider aws-ec2 using identity <your-aws-id-here>

You can then use the EC2 dashboard to locate the instance and confirm that it has started up.

If both the instance and the Druid cluster launch successfully, a few minutes later other messages to STDOUT should follow with information returned from EC2, including the instance ID:

Started cluster of 1 instances
Cluster{instances=[Instance{roles=[zookeeper, druid-mysql, druid-coordinator, druid-broker, druid-historical, druid-realtime], publicIp= ...

The final message will contain login information for the instance.

Note that the Whirr will return an exception if any of the nodes fail to launch, and the cluster will be destroyed. To destroy the cluster manually, run the following command:

% $WHIRR_HOME/bin/whirr destroy-cluster --config $WHIRR_HOME/recipes/druid.properties