abp-multitenancy

ABP Framework — Multi-Tenancy

ABP Framework v10.4 multi-tenancy (SaaS) implementation guide. Tenant resolver, IMultiTenant, ICurrentTenant, database isolation.

Trigger

• "ABP multi-tenancy"
• "ABP tenant"
• "ABP SaaS"
• "ABP IMultiTenant"
• "ABP ICurrentTenant"
• "ABP tenant resolver"
• "ABP subdomain tenant"
• "ABP database per tenant"

Terminology

• Tenant: A customer of the SaaS application
• Host: The company that manages the application
• Multi-Tenancy: A single instance, multiple customers

Configuration

Configure<AbpMultiTenancyOptions>(options =>
{
    options.IsEnabled = true;
});

In the startup templates this is controlled from a single point via the MultiTenancyConsts class.

Database Architectures

Approach	Description
Single Database	All tenants in the same DB, separated by TenantId
Database per Tenant	Each tenant has its own DB
Hybrid	Some tenants share a DB, others have a separate DB

IMultiTenant Interface

public class Product : AggregateRoot<Guid>, IMultiTenant
{
    public Guid? TenantId { get; set; }  // From the IMultiTenant interface
    public string Name { get; set; }
    public float Price { get; set; }
}

Important:

• TenantId is nullable — if null, the entity belongs to the Host
• ABP automatically applies data filtering for the current tenant
• TenantId is set automatically (from ICurrentTenant.Id)

ICurrentTenant

// Properties
CurrentTenant.Id        // Guid? — Current tenant ID
CurrentTenant.Name      // string — Current tenant name
CurrentTenant.IsAvailable  // bool — true if ID is not null

// Changing the tenant (scoped)
using (CurrentTenant.Change(tenantId))
{
    // Within this scope, operations are performed on behalf of the specified tenant
    var count = await _productRepository.GetCountAsync();
}

// Switch to the host context
using (CurrentTenant.Change(null))
{
    // Operation in the host context
}

Data Filtering — Disabling the Multi-Tenancy Filter

public class ProductManager : DomainService
{
    private readonly IRepository<Product, Guid> _productRepository;
    private readonly IDataFilter _dataFilter;

    public ProductManager(IRepository<Product, Guid> productRepository, IDataFilter dataFilter)
    {
        _productRepository = productRepository;
        _dataFilter = dataFilter;
    }

    public async Task<long> GetAllProductCountAsync()
    {
        using (_dataFilter.Disable<IMultiTenant>())
        {
            return await _productRepository.GetCountAsync();
        }
    }
}

Tenant Resolvers

Default Resolvers (In Order)

1. CurrentUserTenantResolveContributor — From user claims (must always be first)
2. QueryStringTenantResolveContributor — ?__tenant=xxx
3. RouteTenantResolveContributor — From the URL path
4. HeaderTenantResolveContributor — From the HTTP header (__tenant)
5. CookieTenantResolveContributor — From the cookie (__tenant)

Changing the Tenant Key

Configure<AbpAspNetCoreMultiTenancyOptions>(options =>
{
    options.TenantKey = "MyTenantKey";
});

Subdomain/Domain Tenant Resolver

// Subdomain: mytenant.mydomain.com
Configure<AbpTenantResolveOptions>(options =>
{
    options.AddDomainTenantResolver("{0}.mydomain.com");
});

// OpenIddict wildcard domain (if a separate Auth Server is used)
PreConfigure<AbpOpenIddictWildcardDomainOptions>(options =>
{
    options.EnableWildcardDomainSupport = true;
    options.WildcardDomainsFormat.Add("https://{0}.mydomain.com");
});

Custom Tenant Resolver

public class MyCustomTenantResolveContributor : TenantResolveContributorBase
{
    public override string Name => "Custom";

    public override Task ResolveAsync(ITenantResolveContext context)
    {
        // Set context.TenantIdOrName
        // Use DI via context.ServiceProvider
        return Task.CompletedTask;
    }
}

// Registration
Configure<AbpTenantResolveOptions>(options =>
{
    options.TenantResolvers.Add(new MyCustomTenantResolveContributor());
});

Fallback Tenant

Configure<AbpTenantResolveOptions>(options =>
{
    options.FallbackTenant = "acme";  // Used when no tenant is found
});

Multi-Tenancy Middleware

app.UseAuthentication();
app.UseMultiTenancy();  // Immediately after authentication

Already configured in the startup templates.

Tenant Store

Tenant Management Module (Recommended)

Included in the startup templates. The ITenantStore implementation fetches tenant information from the DB.

Configuration Data Store (Alternative)

// appsettings.json
"Tenants": [
    {
        "Id": "446a5211-3d72-4339-9adc-845151f8ada0",
        "Name": "tenant1",
        "NormalizedName": "TENANT1"
    },
    {
        "Id": "25388015-ef1c-4355-9c18-f6b6ddbaf89d",
        "Name": "tenant2",
        "NormalizedName": "TENANT2",
        "ConnectionStrings": {
            "Default": "...tenant2's connection string..."
        }
    }
]

Host vs Tenant DbContext

[IgnoreMultiTenancy]  // Always uses the host DB
public class TenantManagementDbContext : AbpDbContext<TenantManagementDbContext> { }

Other Multi-Tenancy Infrastructure

In ABP, the following services are designed to be multi-tenancy-aware:

• BLOB Storing
• Caching
• Data Filtering
• Data Seeding
• Authorization
• Settings

Best Practices

1. Always implement IMultiTenant — For tenant-specific entities
2. Use CurrentTenant.Change with using — The previous value is restored outside the scope
3. Tenant resolver order matters — CurrentUserTenantResolveContributor must always be first
4. Use CurrentTenant.Change(null) for host-side operations
5. Use the Tenant Management module — The appsettings.json approach is only for simple scenarios
6. In the separate DB approach, cross-tenant queries must be implemented yourself

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Related

• EF Core — tenant connection string, IgnoreMultiTenancy
• MongoDB — tenant isolation with MongoDB
• Authorization — permissions with MultiTenancySides
• Settings & Features — tenant-based feature/setting
• ABP Docs: https://abp.io/docs/latest/framework/architecture/multi-tenancy