To say it clear, this diagram is incomplete and at some points probably no fully true. The idea is just to make the getting started simpler by providing a use case and showing the by this.
![overview] (https://raw.githubusercontent.com/michaelgruczel/openstack-cheat-sheet/master/openStackCheatSheet.png)
all components are more or less independent and have rest APIs. Each component potentially interacts with several other components. Die diagram show one virtual use case from a logical point but not from the perspective of real technical interaction
offers and manages virtual machines, compute nodes, it's like AWS EC2
not replicated block storage for attaching and detaching external hard drives to your operating system. The block storage can be used as normal disk storage (e.g. database), for your operating system files. Its like EBS (Elastic Block Store)
replicated, scalabale Object Storage. Storing multimedia content like videos, images, virtual machine images, backups, email storage, archives etc. Can be used for storing static large data like backups, archives etc. It can be accessed with its own API, and is replicated cross datacenter. HTTP based APIs. Swift can be compared to AWS S3
Networking, provide IP address both private and public
This is used for maintaining a catalog for images and is kind of a repository for images, like AMI (Amazon Machine Images). Stores and retrieve virtual machine disk images.
This component is responsible for managing authentication services for all components. Like credentials and authorization, and authentication for users
OpenStack Telemetry Service, statistics regarding the usage, billings
This component manages multiple Cloud applications through an OpenStack-native REST API and a CloudFormation-compatible Query API.
Database as a Service. Trove is Database as a Service for OpenStack. It's designed to run entirely on OpenStack, with the goal of allowing users to quickly and easily utilize the features of a relational database without the burden of handling complex administrative tasks. Cloud users and database administrators can provision and manage multiple database instances as needed. Initially, the service will focus on providing resource isolation at high performance while automating complex administrative tasks including deployment, configuration, patching, backups, restores, and monitoring.
Messaging as a Service. Marconi is a cloud messaging and notification service for developers building applications on top of OpenStack. The service features a web-friendly HTTP API, which developers can use to send messages between the various components of their SaaS and mobile applications, using a variety of communication patterns. Underlying the API is an efficient messaging engine designed with scalability and security in mind.
web-based portal to interact with all the underlying OpenStack services, such as NOVA, Neutron, etc.
Let's assume we want to create a virtual machine by the Web-UI. So we will login into Horizon. Then we want to create a virtual machine, which means the nova module is called for that. But we do not want to create a blank machine, instead we want to have an OS on it. The images are stored in Glance. Maybe the disk size is not big enough, so we will add a disk by using Cinder. After the machine is created it should get an ip, there the neutron module comes in place. The UI is doing all of them in one dialog, so we do not need do request the modules ourselves. After the machine is created we will deploy a software. This software needs maybe a database or a broker. The modules Trove and Marconi can make your live easier (think about problems like vendor login here). Maybe your application stores data which should be available in another datacenter. Normally you have probably a database which runs shared on boot datacenters, but stuff like videos or archives should not be in a database. Here you can use Swift for scalable and reliable Object storeage by APIs.
openstack offer rest api, but there are command line tools as well, see
http://docs.rackspace.com/servers/api/v2/cs-gettingstarted/content/section_gs_install_nova.html
For an easy usage I prepared a vagrant box.
vagrant up
vagrant ssh
Log in by vagrant ssh and then setup of environment
export OS_AUTH_URL=...
export OS_TENANT_ID=...
export OS_TENANT_NAME=...
export OS_PROJECT_NAME=...
export OS_REGION_NAME=...
export OS_USERNAME=...
export OS_PASSWORD=...
create and delete a server
# show images
nova image-list
# show flavors
nova flavor-list
# show running servers
nova list
#start a server (take image hash from image-list call)
nova boot ...
# check server with the id (see boot result) e.g.
nova show ....
# delete server again
nova delete ...
see https://github.com/michaelgruczel/vagrant-nova-client for more details