Keystone

Keystone: The Identity Management Service in OpenStack

Keystone is the OpenStack service that provides identity, token, catalog, and policy services. It is responsible for authenticating and authorizing users and services, ensuring secure access to the OpenStack environment.

How Keystone Works

Keystone operates through several key components and processes:

Identity: Manages user credentials and authentication. Users provide their credentials (e.g., username and password) to Keystone, which validates them and issues an authentication token.
Token: Issues and manages tokens that are used for authenticating subsequent requests. Tokens have a limited lifespan and must be renewed periodically.
Catalog: Provides a service catalog that lists all available OpenStack services and their endpoints. This allows users to discover and interact with the services.
Policy: Manages access control policies that define what actions users and services can perform. Policies are based on roles assigned to users and groups.
Domain: Organizes projects, users, and groups into administrative boundaries, allowing for multi-tenancy and resource isolation.

Practical Analogy

Think of Keystone as the security and reception desk in a large office building:

Identity: The reception desk where visitors check in and provide their identification (credentials). The receptionist verifies their identity and issues a visitor badge (authentication token).
Token: The visitor badge that allows access to certain areas of the building for a limited time. Visitors must renew their badge if they stay longer.
Catalog: The directory at the reception desk that lists all the offices (services) in the building and their locations (endpoints).
Policy: The security policies that determine which areas visitors can access based on their badge type (roles).
Domain: Different floors or sections of the building, each managed separately, representing different companies or departments (projects).

Practical Use-Cases

Multi-Tenant Cloud Environments: Keystone enables cloud providers to manage multiple tenants, each with its own set of users, projects, and resources. This ensures isolation and security between tenants.
Role-Based Access Control (RBAC): Keystone allows administrators to define roles and assign them to users and groups. This ensures that users have the appropriate permissions to perform their tasks without over-privileging.
Service Discovery: The service catalog provided by Keystone helps users discover available OpenStack services and their endpoints, facilitating interaction with the cloud environment.
Federated Identity Management: Keystone supports federated identity, allowing users to authenticate using external identity providers (e.g., LDAP, SAML). This enables single sign-on (SSO) across multiple cloud environments.
Compliance and Auditing: Keystone’s policy management and logging capabilities help organizations comply with security and regulatory requirements by providing detailed audit trails of user activities.