Mellon-MultiTenant-Azure 1.0.21

Mellon.MultiTenant by @PubDev

Package	Version	Alpha
Mellon-MultiTenant
Mellon-MultiTenant-ConfigServer
Mellon-MultiTenant-Azure

Why Mellon, mellon is the Sindarin (and Noldorin) word for "friend", yes I'm a big fan of LoR, so let's be friends?

About The Project

This library was created to supply a set of tools to enable the creation of multi-tenant applications using .net.

Built With

• net6
• steeltoe
• Azure App Configuration
• Spring Cloud Config
• The most important, Love ❤️

Getting Started

Installation

With package Manager:

Install-Package Mellon-MultiTenant

With .NET CLI:

dotnet add package Mellon-MultiTenant

Configurations

There are two ways to configure the settings, via config and through the api

Settings

"MultiTenant": {
    "ApplicationName": "customer-api",
    "HttpHeaderKey": "x-tenant-name",
    "CookieKey": "tenant-name",
    "QueryStringKey": "tenant-name",
    "TenantSource": "Settings",
    "Tenants": [
      "client-a",
      "client-b",
      "client-c"
    ]
}

When TenantSource is set to EnvironmentVariables it will get the tenant list from the environment variable MULTITENANT_TENANTS, this environment variable must contain the list of possible tenants in a single string, separating the tenants using , for example:

$Env:MULTITENANT_TENANTS = 'client-a,client-b,client-c'

Using the API

You can also set the settings using these options while you are adding the services

builder.Services
        .AddMultiTenant(options =>
            options
                .WithApplicationName("customer-api")
                .WithHttpHeader("x-tenant-name")
                .WithCookie("tenant-name")
                .WithQueryString("tenant-name")
                .WithDefaultTenant("client-a")
                .LoadFromAppSettings()
        );

WithApplicationName(string)

• Set the application name

WithHttpHeader(string)

• Set the HTTP Header key, where the tenant name will be passed

WithCookie(string)

• Set the HTTP Cookie key, where the tenant name will be passed

WithQueryString(string)

• Set the HTTP Query String key, where the tenant name will be passed

WithDefaultTenant(string)

• Set for when the tenant is not defined by the caller the lib will set the tenant as the tenant defined within this property, use it just when needed 😉👍

LoadFromSettings

• Set for when the tenant list will be loaded from the settings MultiTenant:Tenants

LoadFromEnvironmentVariable

• Set for when the tenant list will be loaded from the environment variable MULTITENANT_TENANTS

WithHttpContextLoad(Func<HttpContext, string> func)

• When all the possibilities above do not meet your need you can create a custom "Middleware" to identify the tenant based on a HttpContext

WithCustomTenantConfigurationSource<T>()

• T must be an implementation of the interface ITenantConfigurationSource use it to define new a source of configurations for the tenants, for example, if the tenant settings are stored on XML files you could create something like this:

public class LocalXmlTenantSource : ITenantConfigurationSource
{
    private readonly IHostEnvironment _hostEnvironment;

    public LocalTenantSource(
        IHostEnvironment hostEnvironment)
    {
        _hostEnvironment = hostEnvironment;
    }

    public IConfigurationBuilder AddSource(
        string tenant,
        IConfigurationBuilder builder)
    {
        builder.AddXmlFile($"appsettings.{tenant}.xml", true);
        builder.AddXmlFile($"appsettings.{tenant}.{_hostEnvironment.EnvironmentName}.xml", true);

        return builder;
    }
}

Local

This is the default source of settings for the tenants, there is no need to enable it, it will search for the settings on the application following this pattern:

• appsettings.{tenant}.json
• appsettings.{_hostEnvironment.EnvironmentName}.json

It is also worth mentioning that the configurations will also contain:

• appsettings.json
• appsettings.[environment].json
• environment variables

Spring Cloud Config

You can also load the settings from a Spring Cloud Config Server!

To enable the usage you need to install an extra package:

With package Manager:

Install-Package Mellon-MultiTenant-ConfigServer

With .NET CLI:

dotnet add package Mellon-MultiTenant-ConfigServer

Once the package is installed you need to configure its services

builder.Services
        .AddMultiTenant()
        .AddMultiTenantSpringCloudConfig();

To setup Spring Cloud Config on your environment check this reporitory DotNet-ConfigServer

The application name for spring cloud config will be based on the settings MultiTenant.ApplicationName and the label will be tenant name.

Example: customer-api-client-a.yaml

being:

• customer-api the application name
• client-a the tenant name

Moreover, it is worth mentioning that the settings for each customer will also have the settings of the current files:

• appsettings.json
• appsettings.[environment].json
• environment variables

Azure App Configuration

You can also use it as a source of configuration the Azure App Configuration

With package Manager:

Install-Package Mellon-MultiTenant-Azure

With .NET CLI:

dotnet add package Mellon-MultiTenant-Azure

Once the package is installed you need to configure its services

builder.Services
        .AddMultiTenant()
        .AddMultiTenantAzureAppConfiguration();

AddMultiTenantAzureAppConfiguration(Action<AzureMultiTenantOptions> action = null)

if the action is not passed, the connection string used to connect on azure will be loaded from AzureAppConfigurationConnectionString

if you want to elaborate more, on how you are going to connect on Azure, you can use the AzureMultiTenantOptions, there is a property, which is a Func<IServiceProvider, string, Action<AzureAppConfigurationOptions>>, where the first parameter is the ServiceProvider, where you can extract the services; a string, being the tenant name; and the return of this Func must be an Action<AzureAppConfigurationOptions>. For example:

builder.Services
        .AddMultiTenant()
        .AddMultiTenantAzureAppConfiguration(options =>
            options.AzureAppConfigurationOptions = (serviceProvider, tenant) =>
            {
                var configuration = serviceProvider.GetRequiredService<IConfiguration>();

                return azureOptions => azureOptions
                    .Connect(configuration["AzureAppConfigurationConnectionString"])
                    .Select("*", tenant);
            }
        );

Usage / Samples

You can find some examples of how to use this library in the folder /samples

Web API

To enable it on your api you first need to add the services:

builder.Services.AddMultiTenant();

then you need also to register the middleware used to identify the tenant based on the HttpContext

app.UseMultiTenant();

Once that is done you will be able to use the interface IMultiTenantConfiguration, this interface will behave the same as the IConfiguration interface, but contain only the current tenant settings:

Example:

app.MapGet("/", (IMultiTenantConfiguration configuration) =>
{
    return new
    {
        Tenant = configuration.Tenant,
        Message = configuration["Message"],
    };
});

EF Core Migrations:

To use it with EF Core is quite simple, you need to use the interface IMultiTenantConfiguration as mentioned above to setup your EF Context

Setup

builder.Services.AddDbContext<DataBaseContext>(
    (IServiceProvider serviceProvider, DbContextOptionsBuilder options) =>
    {
        var configuration = serviceProvider.GetRequiredService<IMultiTenantConfiguration>();

        options.UseSqlServer(configuration?["ConnectionStrings:DefaultConnection"]);
    });

Migrations

To apply the migrations, you only need to do this:

var tenants = app.Services.GetRequiredService<MultiTenantSettings>();

foreach (var tenant in tenants.Tenants)
{
    using (var scope = app.Services.CreateScope())
    {
        var tenantSettings = scope.ServiceProvider.GetRequiredService<TenantSettings>();

        tenantSettings.SetCurrentTenant(tenant);

        var db = scope.ServiceProvider.GetRequiredService<DataBaseContext>();

        await db.Database.MigrateAsync();
    }
}

app.Run();

Extras

We know that settings can be changed all the time, but to get our applications running on with the latest settings we need to restart the application, it caused downtime and it's not very practical. Keeping that in mind, we added also an endpoint that when called will refresh all the settings for all the tenants or a specific tenant:

• /refresh-settings
• /refresh-settings/{tenantName}

PS: this will work only with AzureAppConfiguration and SpringCloudConfig

Roadmap

• Add unit tests 🧪
• Add new Config Source
• Load the Tenants from a web-api request
• Enable the usage with HanfFire

See the open issues for a full list of proposed features (and known issues).

Contributing

Contributions are what make the open source community such an amazing place to learn, inspire, and create. Any contributions you make are greatly appreciated.

If you have a suggestion that would make this better, please fork the repo and create a pull request. You can also simply open an issue with the tag "enhancement". Don't forget to give the project a star! Thanks again!

1. Fork the Project
2. Create your Feature Branch (git checkout -b feature/AmazingFeature)
3. Commit your Changes (git commit -m 'Add some AmazingFeature')
4. Push to the Branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

Contact

• Humberto Rodrigues - @1bberto - humberto_henrique1@live.com
• Rafael Nagai - @naganaga - rafakenji23@gmail.com

Project Link: https://github.com/1bberto/Mellon.MultiTenant