Although, most of this book will concentrate on examples of Apache Spark installed on physically server-based clusters (with the exception of https://databricks.com/), I wanted to make the point that there are multiple cloud-based options out there. There are cloud-based systems that use Apache Spark as an integrated component, and cloud-based systems that offer Spark as a service. Even though this book cannot cover all of them in depth, I thought that it would be useful to mention some of them:
Databricks is covered in two chapters in this book. It offers a Spark cloud-based service, currently using AWS EC2. There are plans to extend the service to other cloud suppliers (https://databricks.com/).
At the time of writing (July 2015) this book, Microsoft Azure has been extended to offer Spark support.
Apache Spark and Hadoop can be installed on Google Cloud.
The Oryx system has been built at the top of Spark and Kafka for real-time, large-scale machine learning (http://oryx.io/).