Multi-Tenancy & Architecture¶

SkyCMS is designed as a multi-tenant platform from the ground up. A single deployment can serve multiple independent websites, each with its own content, users, storage, database, and configuration — while sharing the same application infrastructure.

Audiences: Developers, Administrators, Evaluators

Jump to:

Multi-Tenancy Model
Tenant Isolation
Multi-Database Support (FlexDb)
Configuration System
Application Architecture
Publisher Architecture
Entity Framework Integration

1. Multi-Tenancy Model¶

Documentation: Multi-Tenancy Configuration · Multi-Tenancy Deep Dive (Developers)

Single Instance, Multiple Sites¶

One deployed application serves all tenants
Each tenant is an independent website with its own domain
Tenants share application code but have isolated data
No per-tenant deployment required — add tenants via configuration

Tenant Resolution¶

Tenants are identified on every HTTP request via domain headers:

x-origin-hostname header (highest priority) — used when behind a CDN or reverse proxy
Host header (fallback) — standard HTTP host detection

Resolution happens early in the middleware pipeline via DomainMiddleware, before any controller code executes.

Tenant Context¶

IDynamicConfigurationProvider (singleton) resolves the current tenant
Per-request scoped services receive tenant context automatically
TenantContext holds the resolved tenant for the current request
All data access is automatically filtered to the current tenant

2. Tenant Isolation¶

Documentation: Tenant Isolation Reference · Multi-Tenancy Deep Dive

Data Isolation¶

Layer	Isolation Mechanism
Content	Pages, articles, media scoped to tenant via `IApplicationDbContext`
Settings	Settings queries filtered by tenant domain
Users	Per-tenant user stores and roles
Files	Per-tenant cloud storage paths
Cache	Cache key prefixing by tenant domain
Cookies	`CookieDomain` claim controls session scope (Sky.Editor)
CDN	Publish and cache purge affect only the tenant's assets
Configuration	Per-tenant configuration records in `DynamicConfigDbContext`

Cookie domain controlled via CookieDomain claim in the user's identity
Prevents session leakage between tenants sharing the same application
Automatically scoped per HttpContext

Anti-Forgery Isolation¶

Anti-forgery tokens are automatically scoped per HttpContext
Each tenant gets its own token validation scope

3. Multi-Database Support (FlexDb)¶

Documentation: FlexDb (Developers) · Database Overview · Cosmos DB · SQL Server · MySQL · SQLite · Database Configuration Reference

AspNetCore.Identity.FlexDb¶

SkyCMS identity storage uses a flexible database provider system that auto-selects the database engine from the connection string — no code changes needed.

Supported Database Providers¶

Provider	Priority	Best For
Azure Cosmos DB	10 (highest)	Global scale, NoSQL, multi-region replication
SQL Server / Azure SQL	20	Enterprise ACID compliance, complex queries
MySQL	30	Open-source relational database
SQLite	40 (lowest)	Local development, single-server deployments, demos

Provider Selection¶

Automatic — Provider detected from connection string format at runtime
Strategy pattern — Each provider implements a detection strategy with priority ordering
Zero code changes — Switch databases by changing the connection string only
Multi-environment — Use different providers per environment (e.g., SQLite in dev, Cosmos in production)

Provider Features¶

Thread-safe concurrent operations across all providers
Personal data protection (encryption) for sensitive user fields
Backward compatibility with legacy Cosmos DB configurations
Database schema auto-initialization on first startup

4. Configuration System¶

Documentation: Configuration Overview · Multi-Tenancy Configuration · Proxy Settings

Dynamic Configuration Provider¶

Runtime configuration resolution without app restart
Per-tenant configuration records stored in DynamicConfigDbContext
Domain-to-tenant mapping
Configuration cached with 10-second TTL for performance
Domain name validation API (ValidateDomainName())
Metrics collection per tenant (usage tracking)

Configuration Precedence¶

Settings are resolved in order (highest priority first):

Environment variables and secret stores
Environment-specific appsettings.{Environment}.json
Base appsettings.json defaults
Dynamic configuration records (per-tenant overrides)

Configurable Categories¶

Database connection strings
Cloud storage connection strings
CDN provider settings
Email provider settings
Multi-tenancy domain mappings
Proxy settings (for reverse proxies and CDNs)
AI provider endpoint settings

5. Application Architecture¶

Documentation: Architecture (Developers) · Middleware Pipeline

CQRS + Mediator Pattern¶

Content operations use a vertical-slice architecture with MediatR:

Commands — Create, Save, Delete, Publish, Trash, Restore, Clone, Import, Promote
Queries — Get, GetList, GetEditable, GetSettings
Handlers — Each command/query has a dedicated handler
Results — Standardized result objects with IsSuccess and error messages

Feature slices organized by domain:

Features/Articles/ — Article CRUD, versioning, publishing
Features/Blogs/ — Blog stream and post management
Features/Layouts/ — Layout creation, import, promotion
Features/Templates/ — Template CRUD, publishing, metadata
Features/Copilot/ — legacy-named AI proxy configuration feature area
Features/Shared/ — Multi-tenant mediator wrapper

Multi-Tenant Mediator¶

MultiTenantMediator wraps MediatR to inject tenant context into every command/query
Ensures all operations are automatically tenant-scoped

Real-Time Communication (SignalR)¶

Three SignalR hubs for real-time features:

Hub	Purpose	Authorization
ChatHub	Editor chat, article locking, save notifications, typing indicators	Authenticated users
LiveEditorHub	Multi-user editing groups, live content updates, editor presence	Authenticated users
PublishingProgressHub	Bulk publish progress streaming	Editors, Administrators

Middleware Pipeline¶

Key middleware in execution order:

DomainMiddleware — Tenant resolution (earliest)
TenantSetupMiddleware — Redirect to setup if tenant not initialized
SetupCompletionFilter — Endpoint filter for setup verification
Standard ASP.NET Core middleware (auth, CORS, rate limiting, anti-forgery)
Controller dispatch

Boot Modules¶

Two boot paths depending on deployment mode:

SingleTenant.Configure() — DI registration and schema initialization for single-tenant deployments
MultiTenant.Configure() — DI registration, schema initialization, and dynamic config wiring for multi-tenant deployments

6. Publisher Architecture¶

Documentation: Publisher Architecture · Publishing Workflow

The Publisher (public-facing site) operates in two modes:

Dynamic Publisher Mode¶

Full server-side HTML rendering from database
Real-time content from ApplicationDbContext
Authentication support (OAuth, Azure B2C)
SEO-optimized meta tags and structured data

Static Website Proxy Mode¶

Pre-rendered HTML files served from cloud storage
Minimal server overhead — pages served from CDN edge
SPA fallback routing for single-page applications
Maximum performance for high-traffic sites

Publisher Services¶

Service	Purpose
`ViewRenderingService`	Render Razor views to HTML strings
`IPublishingService`	Orchestrate publish operations
`IPublishingProgressReporter`	Track and report publish progress
`ICdnServiceFactory`	CDN provider factory (Azure, Cloudflare, CloudFront, Sucuri)
`AzureWebAppPublisher`	Azure App Service deployment
`GraphIntegrationService`	Microsoft Graph for AD group authorization
`RequestContextProvider`	Resolve request context for content delivery

7. Entity Framework Integration¶

Documentation: EF Cross-Provider Compatibility Guide · FlexDb · Database Overview

Cross-Provider Compatibility¶

All EF Core queries are designed to work across all four supported database providers:

No cross-container joins (Cosmos DB limitation)
No inline casts in expression trees (Cosmos DB limitation)
Sequential queries with client-side correlation instead of joins
Pre-computed values for enum conversions before LINQ predicates

Database Contexts¶

Context	Purpose
`ApplicationDbContext`	Main content storage (articles, templates, layouts, blogs, contacts)
`DynamicConfigDbContext`	Tenant configuration and domain mappings
`CosmosIdentityDbContext`	ASP.NET Core Identity storage (users, roles, claims)