Whirr™ Frequently Asked Questions

How do I find my cloud credentials?

On EC2:

  1. Go to http://aws-portal.amazon.com/gp/aws/developer/account/index.html?action=access-key
  2. Log in, if prompted
  3. Find your Access Key ID and Secret Access Key in the "Access Credentials" section, under the "Access Keys" tab. You will have to click "Show" to see the text of your secret access key.

Another good resource is Understanding Access Credentials for AWS/EC2 by Eric Hammond.

Can I specify my own private key?

Yes, by setting whirr.private-key-file (or --private-key-file on the command line). You should also set whirr.public-key-file ( --public-key-file ) at the same time.

Private keys must not have a passphrase associated with them. You can check this with:

grep ENCRYPTED ~/.ssh/id_rsa

If there is no passphrase then there will be no match.

How do I access my cluster from a different network?

By default, access to clusters is restricted to the single IP address of the machine starting the cluster, as determined by Amazon's check IP service . However, some networks report multiple origin IP addresses (e.g. they round-robin between them by connection), which may cause problems if the address used for later connections is different to the one reported at the time of the first connection.

A related problem is when you wish to access the cluster from a different network to the one it was launched from.

In these cases you can specify the IP addresses of the machines that may connect to the cluster by setting the client-cidrs property to a comma-separated list of CIDR blocks.

For example, 208.128.0.0/16,38.102.147.107/32 would allow access from the 208.128.0.0 class B network, and the (single) IP address 38.102.147.107.

How can I start a cluster in a particular location?

By default clusters are started in an arbitrary location (e.g. region or data center). You can control the location by setting location-id (see the configuration guide for details).

For example, in EC2, setting location-id to us-east-1 would start the cluster in the US-East region, while setting it to us-east-1a (note the final a ) would start the cluster in that particular availability zone ( us-east-1a ) in the US-East region.

How can I use a custom image? How can I control the cloud hardware used?

The default image used is dependent on the Cloud provider, the hardware, and the service. Whirr tries to find an image with Ubuntu Server and at least 1024 MB of RAM.

Use image-id to specify the image used, and hardware-id to specify the hardware. Both are cloud-specific.

You can specify the amount of RAM in a cloud agnostic way by setting a value for hardware-min-ram .

In addition, on EC2 you need to set jclouds.ec2.ami-owners to include the AMI owner if it is not Amazon, Alestic, Canonical, or RightScale.

How do I log in to a node in the cluster?

On EC2, if you know the node's address you can do:

ssh -i ~/.ssh/id_rsa <whirr.cluster-user>@host

This assumes that you use the default private key; if this is not the case then specify the one you used at cluster launch.

whirr.cluster-user defaults to the name of the local user running Whirr.

How can I modify the instance installation and configuration scripts?

The scripts to install and configure cloud instances are searched for on the classpath.

(Note that in versions prior to 0.4.0 scripts were downloaded from S3 by default, and could be overridden by setting run-url-base . This property no longer has any effect, so you should instead use the approach explained below.)

If you want to change the scripts then you can place a modified copy of the scripts in a functionsdirectory in Whirr's installation directory. The original versions of the scripts can be found in functionsdirectories in the source trees.

For example, to override the Hadoop scripts, do the following:

cd $WHIRR_HOME 
mkdir functions 
cp services/hadoop/src/main/resources/functions/* functions

Then make your changes to the copies in functions.

The first port of call for debugging the scripts that run on on a cloud instance is the whirr.login the directory from which you launched the whirrCLI.

The script output in this log file may be truncated, but you can see the complete output by logging into the node on which the script ran (see "How do I log in to a node in the cluster?" above) and looking in the /tmp/bootstrapor directories for the script itself, and the standard output and standard error logs.

How do I specify the service version and other service properties?

Some services have a property to control the version number of the software to be installed. This is typically achieved by setting the property whirr.<service-name>.tarball.url . Similarly, some services can have arbitrary service properties set.

See the samples in the recipesdirectory for details for a particular service.

In cases where neither of these configuration controls are supported, you may modify the scripts to install a particular version of the service, or to change the service properties from the defaults. See "How to modify the instance installation and configuration scripts" above for details on how to override the scripts.

How can I install custom packages?

You can install extra software by modifying the scripts that run on the cloud instances. See "How to modify the instance installation and configuration scripts" above.

How do I run Cloudera's Distribution for Hadoop?

You can run CDH rather than Apache Hadoop by running the Hadoop service and setting the whirr.hadoop.install-function and whirr.hadoop.configure-function properties. See the recipesdirectory in the distribution for samples.

How do I run a Cassandra/HBase/ZooKeeper cluster?

See the recipesdirectory in the distribution for samples.

How do I automatically tear down a cluster after a fixed time?

It's often convenient to terminate a cluster a fixed time after launch. This is the case for test clusters, for example. You can achieve this by scheduling the destroy command using the at command from your local machine.

WARNING: The machine from which you issued the at command must be running (and able to contact the cloud provider) at the time it runs.

% echo 'bin/whirr destroy-cluster --config hadoop.properties' | at 'now + 50 min'

Note that issuing a shutdown command on an instance may simply stop the instance, which is not sufficient to fully terminate the instance, in which case you would continue to be charged for it. This is the case for EBS boot instances, for example.

You can read more about this technique on Eric Hammond's blog .

Also, Mac OS X users might find this thread a useful reference for the at command.

How do I start a machine without having a cluster role?

Sometimes you need to provision machines in the same cluster without having a specific role. For this you can use "noop" as a role name when specifying the instance templates.

whirr.instance-templates=3 zookeeper,1 noop 
# will start three machines with zookeeper and one machine just with the OS