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登录及身份认证是现代web应用最基本的功能之一，对于企业内部的系统，多个系统往往希望有一套SSO服务对企业用户的登录及身份认证进行统一的管理，提升用户同时使用多个系统的体验，Keycloak正是为此种场景而生。本文将简明的介绍Keycloak的安装、使用，并给出aspnetcore 应用如何快速接入Keycloak的示例。
Keycloak是什么
Keycloak是一种面向现代应用和服务的开源IAM（身份识别与访问管理）解决方案
Keycloak提供了单点登录（SSO）功能，支持OpenID Connect、OAuth 2.0、SAML 2.0标准协议，拥有简单易用的管理控制台，并提供对LDAP、Active Directory以及Github、Google等社交账号登录的支持，做到了非常简单的开箱即用。
Keycloak常用核心概念介绍
首先通过官方的一张图来了解下整体的核心概念
这里先只介绍4个最常用的核心概念：
-
Users: 用户，使用并需要登录系统的对象 -
Roles: 角色，用来对用户的权限进行管理 -
Clients: 客户端，需要接入Keycloak并被Keycloak保护的应用和服务 Realms: 领域，领域管理着一批用户、证书、角色、组等，一个用户只能属于并且能登陆到一个域，域之间是互相独立隔离的， 一个域只能管理它下面所属的用户
Keycloak服务安装及配置
安装Keycloak
Keycloak安装有多种方式，这里使用Docker进行快速安装
登录后复制
docker run -d --name keycloak -p 8080:8080 -e KEYCLOAK_USER=admin -e KEYCLOAK_PASSWORD=admin jboss/keycloak:13.0.0访问http://localhost:8080并点击Administration Console进行登录
创建Realm
创建一个新的realm: demo，后续所有的客户端、用户、角色等都在此realm中创建
创建客户端
创建前端应用客户端
创建一个新的客户端：KeycloakAuthaspnet，Access Type选择public
关于客户端的访问类型（Access Type）
上面创建的客户端的访问类型分别是confidential，那么为什么分别选择这种类型，实际不同的访问类型有什么区别呢？
事实上，Keycloak目前的访问类型共有3种：
confidential：适用于服务端应用，且需要浏览器登录以及需要通过密钥获取access token的场景。典型的使用场景就是服务端渲染的web系统。public：适用于客户端应用，且需要浏览器登录的场景。典型的使用场景就是前端web系统，包括采用vue、react实现的前端项目等。bearer-only：适用于服务端应用，不需要浏览器登录，只允许使用bearer token请求的场景。典型的使用场景就是restful api。
Access Type 里面选 Confidential，然后才有 Client Secret ，保存之后，会出现Credentials的Tab，记录下这里的secret，后面要用到
创建用户和角色
创建角色
创建2个角色：admin、user
还可以创建全局的角色
创建用户
创建1个用户：geffzhang
绑定用户和角色
给geffzhang 用户分配角色admin和user
aspnetcore 应用集成Keycloak简明指南
添加 Microsoft.AspNetCore.Authentication.OpenIdConnect 和 Microsoft.AspNetCore.Identity 包
<Project Sdk="Microsoft.NET.Sdk.Web">
<PropertyGroup>
<TargetFramework>net5.0</TargetFramework>
<UserSecretsId>afab524d-850e-499a-bc13-98f61ca0eb3b</UserSecretsId>
<DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>
</PropertyGroup>
<ItemGroup>
<PackageReference Include="Microsoft.AspNetCore.Authentication.OpenIdConnect" Version="5.0.5" />
<PackageReference Include="Microsoft.AspNetCore.Identity" Version="2.2.0" />
<PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.10.8" />
<PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="5.0.2" />
</ItemGroup>
</Project>
Appsettings.json
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddControllersWithViews();
services.AddAuthentication(options =>
{
//Sets cookie authentication scheme
options.DefaultAuthenticateScheme = CookieAuthenticationDefaults.AuthenticationScheme;
options.DefaultSignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
options.DefaultChallengeScheme = OpenIdConnectDefaults.AuthenticationScheme;
})
.AddCookie(cookie =>
{
//Sets the cookie name and maxage, so the cookie is invalidated.
cookie.Cookie.Name = "keycloak.cookie";
cookie.Cookie.MaxAge = TimeSpan.FromMinutes(60);
cookie.Cookie.SecurePolicy = CookieSecurePolicy.SameAsRequest;
cookie.SlidingExpiration = true;
})
.AddOpenIdConnect(options =>
{
/*
* ASP.NET core uses the http://*:5000 and https://*:5001 ports for default communication with the OIDC middleware
* The app requires load balancing services to work with :80 or :443
* These needs to be added to the keycloak client, in order for the redirect to work.
* If you however intend to use the app by itself then,
* Change the ports in launchsettings.json, but beware to also change the options.CallbackPath and options.SignedOutCallbackPath!
* Use LB services whenever possible, to reduce the config hazzle 
*/
//Use default signin scheme
options.SignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
//Keycloak server
options.Authority = Configuration.GetSection("Keycloak")["ServerRealm"];
//Keycloak client ID
options.ClientId = Configuration.GetSection("Keycloak")["ClientId"];
//Keycloak client secret
options.ClientSecret = Configuration.GetSection("Keycloak")["ClientSecret"];
//Keycloak .wellknown config origin to fetch config
options.MetadataAddress = Configuration.GetSection("Keycloak")["Metadata"];
//Require keycloak to use SSL
options.RequireHttpsMetadata = false;
options.GetClaimsFromUserInfoEndpoint = true;
options.Scope.Add("openid");
options.Scope.Add("profile");
//Save the token
options.SaveTokens = true;
//Token response type, will sometimes need to be changed to IdToken, depending on config.
options.ResponseType = OpenIdConnectResponseType.Code;
//SameSite is needed for Chrome/Firefox, as they will give http error 500 back, if not set to unspecified.
options.NonceCookie.SameSite = SameSiteMode.Unspecified;
options.CorrelationCookie.SameSite = SameSiteMode.Unspecified;
options.TokenValidationParameters = new TokenValidationParameters
{
NameClaimType = "name",
RoleClaimType = ClaimTypes.Role,
ValidateIssuer = true
};
});
/*
* For roles, that are defined in the keycloak, you need to use ClaimTypes.Role
* You also need to configure keycloak, to set the correct name on each token.
* Keycloak Admin Console -> Client Scopes -> roles -> mappers -> create
* Name: "role client mapper" or whatever you prefer
* Mapper Type: "User Client Role"
* Multivalued: True
* Token Claim Name: role
* Add to access token: True
*/
/*
* Policy based authentication
*/
services.AddAuthorization(options =>
{
//Create policy with more than one claim
options.AddPolicy("users", policy =>
policy.RequireAssertion(context =>
context.User.HasClaim(c =>
(c.Value == "user") || (c.Value == "admin"))));
//Create policy with only one claim
options.AddPolicy("admins", policy =>
policy.RequireClaim(ClaimTypes.Role, "admin"));
//Create a policy with a claim that doesn't exist or you are unauthorized to
options.AddPolicy("noaccess", policy =>
policy.RequireClaim(ClaimTypes.Role, "noaccess"));
});
/*
* Non policy based authentication
* Uncomment below and comment the policy section
*/
//services.AddAuthorization();
}
经过上述的配置，通过oidc 很容易就接入到了Keycloak。具体代码请参见：https://github.com/NanoFabricFX/AspNetCore-keycloak/tree/dotnet5。
运行效果，第一次访问项目会跳转Keycloak登录页
用户登陆geffzhang
总结
Keycloak部署及接入简单，轻量的同时功能又不失强大，非常适合企业内部的SSO方案。在Identity Server4 收费的背景之下，微软计划在.NET 6里面继续集成，已经被社区骂的狗血喷头https://devblogs.microsoft.com/aspnet/asp-net-core-6-and-authentication-servers/
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