Multi-Tenancy — Overview

Granit.MultiTenancy provides a complete multi-tenancy stack for SaaS applications. A pipeline of pluggable resolvers extracts the tenant from HTTP requests, sets an AsyncLocal context for the entire request, and downstream modules — persistence, caching, messaging — automatically scope their operations to the active tenant.

Why Granit multi-tenancy

Zero manual WHERE clauses — EF Core query filters handle tenant isolation transparently
Four built-in resolvers — subdomain, header, JWT claim, query string
Three isolation strategies — shared database, schema-per-tenant, database-per-tenant — switchable per tenant at runtime
Cache key isolation — automatic TenantId prefix on all FusionCache keys
Host/tenant schema separation — configurable via appsettings.json
Message propagation — Wolverine automatically carries tenant context across async boundaries
Automatic provisioning — new tenants get schema creation, EF Core migrations, and data seeding out of the box

Package structure

Granit.MultiTenancy — Resolvers, CurrentTenant, middleware
Granit.MultiTenancy.EntityFrameworkCore — Tenant store, EF Core persistence
Granit.MultiTenancy.Endpoints — Tenant admin API endpoints
Granit.Persistence.EntityFrameworkCore — Isolation strategies, GranitDbDefaults, SchemaEnsurer
Granit.MultiTenancy.Provisioning — Automatic tenant provisioning handler
Granit.Caching — TenantAwareFusionCache decorator

Package	Role
`Granit.MultiTenancy`	Resolvers, `CurrentTenant`, middleware, options
`Granit.MultiTenancy.EntityFrameworkCore`	`ITenantReader`/`ITenantWriter`, tenant aggregate, EF persistence
`Granit.Persistence.EntityFrameworkCore`	`GranitDbDefaults`, `SchemaEnsurer`, isolation strategy factories
`Granit.MultiTenancy.Provisioning`	`TenantProvisioningHandler` — automatic tenant provisioning on creation
`Granit.Persistence.EntityFrameworkCore.Hosting`	`ITenantProvisioner`, `AutoTenantProvisioner` — schema + migration + seeding
`Granit.Caching`	`TenantAwareFusionCache` — automatic cache key isolation

Architecture

flowchart TB
    subgraph HTTP["HTTP Pipeline"]
        REQ[Request] --> RES[Resolver Pipeline]
        RES --> CTX["ICurrentTenant (AsyncLocal)"]
    end

    subgraph DATA["Data Layer"]
        CTX --> EF["EF Core Query Filters"]
        CTX --> CACHE["TenantAwareFusionCache"]
        CTX --> WV["Wolverine Context Propagation"]
    end

    subgraph ISOLATION["Isolation Strategy"]
        EF --> SD[SharedDatabase<br/>WHERE TenantId = @id]
        EF --> SPT[SchemaPerTenant<br/>SET search_path]
        EF --> DPT[DatabasePerTenant<br/>per-tenant connection]
    end

Quick start

[DependsOn(typeof(GranitMultiTenancyModule))]
public class AppModule : GranitModule { }

{
  "MultiTenancy": {
    "IsEnabled": true,
    "DomainTemplate": "{0}.myapp.com"
  },
  "TenantIsolation": {
    "Strategy": "SchemaPerTenant",
    "HostSchema": "host"
  }
}

app.UseAuthentication();
app.UseGranitMultiTenancy();   // After auth, before authorization
app.UseAuthorization();

Section contents

This section covers multi-tenancy in depth:

Tenant Resolvers — the four built-in resolvers and how to add custom ones
Isolation Strategies — shared database, schema-per-tenant, database-per-tenant, and the hybrid model
Host vs Tenant — how to separate host infrastructure from tenant data using GranitDbDefaults
Cache Isolation — automatic tenant-scoped cache keys with TenantAwareFusionCache
Automatic Provisioning — zero-config schema creation, migrations, and seeding for new tenants