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The following image is particularly indicative of OpenStack's purposes: it shows how the framework of the platform consists of three large functionalities (compute, network and storage), managed overall by a data center and ready to interact with the user through dashboards (a panel accessible via browser) or appropriate programming APIs. On the official website of the project (https://www.openstack.org/software/) you can find a considerably more detailed version, which shows the complexity of the platform.
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The most important modules of Openstack are:
- Nova (Compute): is the main module, which controls the entire platform. It is used to manage instances of virtual machines and internal communication systems. Its tasks are carried out through various specialized services, coordinated to collaborate. Among these, nova-schedule stands out, which deals with allocating instances on physical machines and, nova-compute, which communicates with the hypervisor installed on the physical machine to manage the various phases of an instance, from startup to shutdown;
- Neutron (Network): is the module specialized in network communication;
- Swift (Object Storage): is a distributed storage system designed for high reliability and scalability. Ideal for managing very large storage spaces to be dedicated to online storage or backup;
- Keystone (Identity): centralizes all the authentication and authorization problems for the various OpenStack modules;
- Glance (Image Service): this is the virtual image management service. It consists of three main parts: a database (typically MySQL), a cataloging service for virtual images and a large set of APIs for interaction;
- Horizon (Dashboard): it is the Web interface with which the user communicates;
- Cinder (Block Storage): is the module that manages block volumes for saving data;
- Octavia (Load Balancing): a scalable load balancer service.
The present guide is structured in the following sections:
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