Project Initialization Process with IdentityServer4 + ASP.Net Identity

Conclusion#

Initialize IdentityServer4 + user system in one go using the is4aspid template + Migration + Seed.

Where It’s Suitable#

Need to quickly set up an OAuth / OpenID Connect Server
Want to integrate ASP.NET Identity (username/password login)
Building an internal authentication service or SSO system
Testing or learning IdentityServer architecture

Steps#

1. Install Template and Create Project#

Use dotnet new to install the IdentityServer4 template
Create a project integrating ASP.NET Identity (is4aspid)
Why: This template comes with built-in login and user management, so you don’t have to implement it yourself.

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# 安裝範本
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dotnet new -i identityserver4.templates
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# 建立專案（含 ASP.NET Identity）
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dotnet new is4aspid -n IdentityServerAspNetIdentity

Common Templates Comparison:

Template	Purpose
is4empty	Empty project
is4inmem	In-memory testing
is4ef	DB storage configuration
is4aspid	Integrate username/password login (recommended)

2. Create Database (Migration)#

Add Migration (generate table schema)
Update database (create Identity + IdentityServer Tables)
Why: IdentityServer needs a DB to store client / user / config

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# 建立 Migration
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dotnet ef migrations add InitialCreate
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# 建立資料表
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dotnet ef database update

3. Initialize Seed Data#

Add /seed parameter when starting the project
Automatically writes test users, Client settings
Why: Avoids manual data creation, allowing direct testing of the login process

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dotnet run /seed

Core code:

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var seed = args.Contains("/seed");
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if (seed)
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{
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    args = args.Except(new[] { "/seed" }).ToArray();
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}
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var host = CreateHostBuilder(args).Build();
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if (seed)
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{
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    // 初始化資料
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    var config = host.Services.GetRequiredService<IConfiguration>();
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    var connectionString = config.GetConnectionString("DefaultConnection");
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    SeedData.EnsureSeedData(connectionString);
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    return 0;
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}

Additional Notes#

IdentityServer4 is no longer maintained; for production projects, it’s recommended to evaluate Duende (paid).
Seed is only suitable for development environments; for production, use Migration + Script for management.
The /seed design is convenient, but avoid misusing it in Production.

Wrap-up#

Three steps to complete authentication system initialization. The key is not writing code, but choosing the right template. In engineering: first make it run, then optimize.