As relying on cloud computing is becoming a disadvantage due to privacy, security, and reliability concerns, there interest for open-source cloud-computing tools is rising as the source code of the cloud is freely available. These resources could help companies to build and customize their own computing clouds to work alongside more powerful commercial solutions. Here are the Cloud Computing environments out there and are open source.

1. Enomaly Elastic Computing

Enomaly’s Elastic Computing Platform (ECP) is the answer for carriers and hosting providers, and their customers, who want to benefit from the power, flexibility, and economies of cloud computing. Over 15,000 companies use ECP to operate cloud computing platforms, deliver infrastructure-on-demand services to their customers and users, enjoy dynamic provisioning and scaling for their computing workloads, and experience the benefits of cloud computing for the enterprise

2. Nebula

Nebula is a Cloud Computing pilot under development at NASA Ames Research Center. It integrates a set of open-source components into a seamless, self-service platform, providing high-capacity computing, storage and network connectivity using a virtualized, scalable approach to achieve cost and energy efficiencies. Nebula is currently being used for education and public outreach, for collaboration and public input, and also for mission support.

3. Nimbus

Nimbus is a set of open source tools that together provide an "Infrastructure-as-a-Service" (IaaS) cloud computing solution.Nimbus allows a client to lease remote resources by deploying virtual machines (VMs) on those resources and configuring them to represent an environment desired by the user.

4. OpenNebula

OpenNebula is an open-source toolkit to easily build any type of cloud: private, public and hybrid. OpenNebula has been designed to be integrated with any networking and storage solution and so to fit into any existing data center.

With OpenNebula you can transform your data center into a flexible and agile virtual infrastructure which dynamically adapts to the changing demands of the service workload.

5. Eucalyptus

Eucalyptus is an open-source infrastructure for the implementation of cloud computing on computer clusters. Its name is an acronym for "Elastic Utility Computing Architecture for Linking Your Programs To Useful Systems". Eucalyptus provides an  interface that is compatible with Amazon Web Services cloud computing interface. Eucalyptus is available as a source package, RPM, and a Rocks disk image.

6. Cloud computing with Red Hat

Cloud computing with Red Hat enterprise software is a web-scale virtual computing environment powered by Amazon Web Services. It provides everything needed to develop and host applications: compute capacity, bandwidth, storage, and the leading open source operating system platform, Red Hat Enterprise Linux.

7. Cloudera

Cloudera’s Distribution for Hadoop (CDH) packages the popular open-source software for easy installation and deployment. Users of CDH can take advantage of Cloudera Desktop for data import and export, cluster monitoring and administration, and job creation and collaboration. Together these products make it easy to install, configure, run and use a Hadoop cluster for critical business data management tasks