Cinder is the block storage service of the OpenStack cloud computing platform. Its main job is to manage and provide access to block storage devices to other services in the OpenStack environment. Essentially, Cinder is responsible for handling persistent storage for virtual machines running in an OpenStack cloud.

The block storage devices that Cinder manages can be attached to compute instances (virtual machines) and accessed by the guest operating system in the same way that a physical server accesses a physical hard drive. This provides a way for users to handle larger amounts of data than would fit on a typical server. It can also be used for scenarios where data should survive beyond the life of a single compute instance.

Cinder's architecture consists of several key components, including:

• Cinder API Service (c-api): Provides the API endpoints for all Cinder services and is the primary interface for users and services to interact with Cinder.
• Cinder Scheduler Service (c-sch): Handles requests from the API service, deciding where to fulfill these requests based on the current state of the system.
• Cinder Volume Service (c-vol): Manages the actual block storage devices, carrying out instructions such as creating, attaching, or deleting block storage devices.
• Cinder Backup Service (c-bak): Handles backups of the block storage devices.

Cinder supports a wide variety of storage backends, both from open-source projects (like Ceph and LVM) and from proprietary vendors (like NetApp, EMC, etc.), which makes it a flexible choice for diverse storage requirements in an OpenStack cloud.

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Using the Cinder Repository

In order to run unit tests and PEP8 checks from the Cinder repository, you will need to setup your Python environment first. Here is a general guide:

🚀 Clone the Cinder repository: If you haven't already, clone the Cinder repository from OpenStack's Git. You can do this using the following command:

🚀 Setup a virtual environment: It's a good practice to create a virtual environment to keep the project and its dependencies isolated from your other Python projects. You can do this using venv module which is included in standard Python3.

Install the required packages: Install the packages required for development, including the ones required for testing.

Once your environment is set up, you can run unit tests and PEP8 checks.

You may need to install tox if it's not already installed:

🚀 Note: These commands need to be run from the root directory of your local Cinder repository. If you face any issues, it's always a good idea to check the official OpenStack documentation, or reach out on the OpenStack development mailing list for advice.

🚀 Run Unit Tests: You can run the unit tests using the following command:

This will run all the Python3 unit tests in the Cinder repository.

🚀 Run PEP8 Checks: PEP8 checks can be run with the following command:

This will run the PEP8 compliance tests on the Cinder codebase.
 

🚀 Tox is a great tool because it lets you automate and standardize testing in Python, and it's used throughout the OpenStack project. The -e option is used to specify the environment.