This is a special post as it remarks my first contribution to a small open-source project and also to my ex-colleagues during my brief time at SICS.
This project is called Karamel. Karamel is a tool that simplifies big data deployments on a selection of cloud providers like AWS and Google Cloud Engine, in addition to baremetal cluster setups. It is quite easy to get started, you simply need to define your cluster in a file, submit it to the application and do one click!
With this tool you can easily have al big data cluster up and running in a few clicks which will have preinstalled hadoop , Apache Flink or even Apache Spark. In addition, it is the preferred tool for testing out a new hadoop distribution named Hops which try to address the challenges and issues you could face when you work with very large scale hadoop clusters (for example, how to achieve high availability of the namenode)
Deploying Clusters with Karamel
In the rest of this article, I will describe the process of creating a simple cluster running apache Flink in order to make a deployment using Karamel towards an Openstack environment. We will also go over how you can write a cluster file to be deployed using this tool and how you need to configure the Karamel in order to communicate with your cluster.
Before we start
In order to deploy our Hadoop cluster on Openstack, first we will need to get a copy of the latest version of Karamel, you can do it here. Here you will find guidelines to get started with other providers like AWS. You may download one of the available versions that have support for Openstack (version 0.2.0 onwards should do it) or download the source code and build the application with maven.
Working with Karamel
Getting started with Karamel is quite easy, before launching our cluster, we will need to define the configuration of a cluster. In a cluster definition file, we can identify 4 core elements to describe you cluster: Provider, Cookbooks, Attributes and Groups.
In order to understand the role of each core component, we will go through a simple example cluster, let’s imagine that I want to deploy a simple Hadoop cluster with Apache Flink running a namenode and 20 datanodes using an Openstack Infrastructure.
So how can I express this information in Karamel? In addition, if we want to deploy a wordcount job when the cluster is ready, how can we achieve this? How can Karamel allow us to express this business needs? This is how you would do it, as shown on the following file:
In this cluster, we can see 3 different code blocks gathering all the information we need for Karamel to satisfy our cluster needs.
The first segment of the file contains the provider specific information, for Openstack; we make use of the keyword nova in order to tell Karamel that this is an Openstack cluster and we are going to make use of the Openstack Nova Controller.
After the keyword nova, it follows key parameters that Openstack will make use to deplou the necessary resources to run our software on.
Flavor: This corresponds to a specific hardware configuration for the VM, this is similar to Amazon’s EC2 instance descriptors. Openstack refers to them as flavors and each one specifies a configuration (CPU, RAM) and are not the same for everyone, as these are configured by the needs of the organization. To simplify this, Karamel makes use of the flavor id attached to your VM configuration.
Image: This corresponds to the VM image you want to launch stored in your Openstack system. In this case, we make use of the generated ID when you store your image in your Openstack project.
The following code block, gathers the software that we will want to install on our nodes. For this purpose, Karamel makes use of Chef Cookbooks that get will be processed on the nodes by running Chef Solo. To simplify the transfer of the Cookbooks, they should be accessible by the application through Git so it can clone them and execute the recipes on the nodes.
For this example, we want to install Apache Hadoop and Apache Flink so we indicate this Karamel by the keyword Cookbook and specifying the repositories where our Cookbooks are stored plus the branch we want to checkout.
Under the groups sections, we define the cluster structure around groups of components and services. Here, we specify the number of nodes and the recipes that will install the services to run on those nodes.
In this, blog post we went over roughly how Karamel now has support to deploy clusters in Openstack based infrastructures. This gives you the opportunity to play with hadoop, flink or spark directly in your private cloud reducing the time you need to configure a whole cluster.