Multi-Tenancy

PolarSharp.MultiTenant wraps Finbuckle.MultiTenant to give each tenant their own isolated PolarClient with its own access token, circuit breaker, connection pool, and rate limiter.

Installation

dotnet add package PolarSharp.MultiTenant

Configuration

{
  "PolarSharp": {
    "MultiTenant": {
      "Strategy": "Header",
      "Header": { "Name": "X-Tenant-ID" },
      "Tenants": [
        {
          "Id": "acme",
          "Identifier": "acme",
          "Name": "Acme Corp",
          "PolarAccessToken": "tok_live_acme",
          "Server": "Production"
        },
        {
          "Id": "beta",
          "Identifier": "beta",
          "Name": "Beta Inc",
          "PolarAccessToken": "tok_sandbox_beta",
          "Server": "Sandbox"
        }
      ]
    }
  }
}

Registration

builder.Services
    .AddPolarInfrastructure(builder.Configuration)
    .AddPolarMultiTenant();

// ...

app.UsePolarInfrastructure();   // calls app.UseMultiTenant() automatically

Tenant resolution strategies

Strategy	How tenant is identified	Config key
Header (default)	HTTP request header	PolarSharp:MultiTenant:Header:Name (default: X-Tenant-ID)
Route	Route parameter	PolarSharp:MultiTenant:Route:Parameter (default: tenantId)
Hostname	Subdomain / hostname	PolarSharp:MultiTenant:Hostname:Template (default: __tenant__.*)
Claim	JWT claim value	PolarSharp:MultiTenant:Claim:Type (default: tid)

Using the per-tenant client

Inject IMultiTenantPolarClientFactory — it resolves the correct PolarClient for the current request's tenant automatically:

app.MapGet("/orders", async (IMultiTenantPolarClientFactory factory, CancellationToken ct) =>
{
    var polar = factory.GetClientForCurrentTenant();
    var result = await polar.Orders.EmptyPathSegment.GetAsync(cancellationToken: ct);
    return Results.Ok(result);
});

Bulkhead isolation

Each tenant gets independent infrastructure:

• Connection pool — one SocketsHttpHandler per tenant; one tenant's high throughput doesn't starve others
• Circuit breaker — Tenant A's repeated failures open Tenant A's breaker only; Tenant B is unaffected
• Rate limiter — per-tenant concurrency cap

This means a single misbehaving tenant cannot cascade failures to other tenants.

Programmatic tenant registration

For tenants that aren't known at startup:

builder.Services
    .AddPolarInfrastructure(builder.Configuration)
    .AddPolarMultiTenant(opts =>
    {
        opts.Strategy = TenantStrategy.Claim;
        opts.Claim.Type = "polar_tenant_id";
        opts.Tenants.Add(new PolarTenantInfo
        {
            Id = "enterprise-a",
            Identifier = "enterprise-a",
            Name = "Enterprise A",
            PolarAccessToken = "tok_live_ea",
        });
    });