Multi-tenant application

[GioviQ]

Hi, I have a multi-tenant application where every user has its own db, so the connection string is created runtime. Is it possible to use Aspire with this kind of multy tenancy? Thank you

Now in my dbcontext I use something like

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer($"Data Source=.\\SQLEXPRESS;Initial Catalog=DinDini-{_userSession.UserId.ToCompressedString()};Trusted_Connection=True;MultipleActiveResultSets=true;Encrypt=False;");
        }

[davidfowl]

How do you want to use aspire in this situation?

[GioviQ]

I would like every db per user to be created inside one db server container.

I only watched some recent videos about Aspire, I have to decide if I can embrace Aspire or not for this scenario.

[davidfowl]

You can't create a database server after the apphost has started. I don't know if that affects your planned usage but you can determine if it's useful for your scenario based on that.

[GioviQ]

I don't need to create a database server after the apphost has started, this can be create one time as soon as possible as usual, I need to create databases after apphost has started. In the snippet above I use a dynamic connection string to create a database per user in the same database server. So it is impossible to create runtime connection string in Aspire?

[davidfowl]

Because I was interested, I build you a small sample.

This is the apphost:

var builder = DistributedApplication.CreateBuilder(args);

var pg = builder.AddPostgres("pg").WithPgAdmin();

builder.AddProject<Projects.WebApplication1>("api")
       .WithReference(pg);

builder.Build().Run();

App:

using Microsoft.EntityFrameworkCore;
using Npgsql;

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddDbContext<AppDbContext>();
builder.EnrichNpgsqlDbContext<AppDbContext>();

// Register the TenantContext as scoped so we can set it in the request pipeline
builder.Services.AddScoped<TenantContext>();

var app = builder.Build();

app.Use((context, next) =>
{
    var tenantId = (string?)context.Request.Query["tenantId"] ?? "default";

    // Set the tenantId in the TenantContext based on the query string
    context.RequestServices.GetRequiredService<TenantContext>().TenantId = tenantId;
    return next();
});

app.MapGet("/", async (AppDbContext context) =>
{
    await context.Database.EnsureCreatedAsync();

    // Random product
    var product = new Product
    {
        Name = "Product " + Guid.NewGuid().ToString()[..5],
        Price = Random.Shared.Next(100, 1000)
    };

    await context.Products.AddAsync(product);
    await context.SaveChangesAsync();

    return await context.Products.ToListAsync();
});

app.Run();

class AppDbContext(IConfiguration configuration, 
                   TenantContext tenantContext,
                   DbContextOptions<AppDbContext> options) : DbContext(options)
{
    public DbSet<Product> Products { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
    {
        // Read the connection string from the configuration and set the database based on the tenantId
        var builder = new NpgsqlConnectionStringBuilder(configuration.GetConnectionString("pg"))
        {
            // Set the database based on the tenantId
            Database = tenantContext.TenantId
        };

        options.UseNpgsql(builder.ConnectionString);
    }
}


class Product
{
    public int Id { get; set; }
    public required string Name { get; set; }
    public decimal Price { get; set; }
}

class TenantContext
{
    public required string TenantId { get; set; }
}

[GioviQ]

Thank you, this is exactly what I meant!