Keycloak client for ASP.NET Core

Question

Is there any existing Keycloak client for Asp.net Core? I have found a NuGet package for .net but it doesn't work with Core. Do you have any ideas how to easily integrate with this security server (or maybe using any other alternatives)?

Answer 1

I've played a bit with this today. The most straightforward way is too use OpenId standard.

In Startup.cs I used OpenIdConnect Authentication:

    public void Configure(...)
    { (...)
         app.UseCookieAuthentication(new CookieAuthenticationOptions
        {
            AuthenticationScheme = CookieAuthenticationDefaults.AuthenticationScheme,
            AutomaticAuthenticate = true,
            CookieHttpOnly = true,
            CookieSecure = CookieSecurePolicy.SameAsRequest
        });
        app.UseOpenIdConnectAuthentication(CreateKeycloakOpenIdConnectOptions());`(...)
 }`

OpenIdConnectOptions method:

private OpenIdConnectOptions CreateKeycloakOpenIdConnectOptions()
    {
        var options = new OpenIdConnectOptions
        {
            AuthenticationScheme = "oidc",
            SignInScheme = CookieAuthenticationDefaults.AuthenticationScheme,
            Authority = Configuration["Authentication:KeycloakAuthentication:ServerAddress"]+"/auth/realms/"+ Configuration["Authentication:KeycloakAuthentication:Realm"],
            RequireHttpsMetadata = false, //only in development
            PostLogoutRedirectUri = Configuration["Authentication:KeycloakAuthentication:PostLogoutRedirectUri"],
            ClientId = Configuration["Authentication:KeycloakAuthentication:ClientId"],
            ClientSecret = Configuration["Authentication:KeycloakAuthentication:ClientSecret"],
            ResponseType = OpenIdConnectResponseType.Code,
            GetClaimsFromUserInfoEndpoint = true,
            SaveTokens = true

        };
        options.Scope.Add("openid");
        return options;
    }

In appsettings.json add configuration for Keycloak:

{
  (...),
  "Authentication": {
    "KeycloakAuthentication": {
      "ServerAddress": "http://localhost:8180",
      "Realm": "demo",
      "PostLogoutRedirectUri": "http://localhost:57630/",
      "ClientId": "KeycloakASPNETCore",
      "ClientSecret": "secret-get-it-in-keycloakConsole-client-credentials"
    }
  }
}

Keycloak client is configuerd as followed:

• Client settings,
• I've added 'accounting' role for test,
• I added mapper 'member_of' of type 'User Client Role' for roles so that roles are added in the claims

If I want to Authorize user by role I do something like this:

Add authorization by claims in ConfigureServices method:

public void ConfigureServices(IServiceCollection services)
    {
        (...)

        services.AddAuthorization(options =>
        {
            options.AddPolicy("Accounting", policy =>
            policy.RequireClaim("member_of", "[accounting]")); //this claim value is an array. Any suggestions how to extract just single role? This still works.
        });
    }

I've edited get method in ValuesController (Default Web API template):

[Authorize(Policy = "Accounting")]
[Route("api/[controller]")]
public class ValuesController : Controller
{
    // GET api/values        
    [HttpGet]
    public Dictionary<string,string> Get()
    {
        var userPrinciple = User as ClaimsPrincipal;
        var claims = new Dictionary<string, string>();

        foreach (var claim in userPrinciple.Claims)
        {
            var key = claim.Type;
            var value = claim.Value;

            claims.Add(key, value);
        }


        return claims;
    }

If I login with user that has accounting role or is in group that has accounting role, it should display my user claims on address localhost:57630/api/values.

I hope this works for you.

Edit: .NET Core 2 Hi everyone! The way my app works changed quite a bit and I have not fully tested .NET Core 2 yet, but you can still try connecting to Keycloak like this in ConfigureServices:

        services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
            .AddJwtBearer(options =>
            {

                options.Authority = Configuration["Authentication:KeycloakAuthentication:ServerAddress"] + "/auth/realms/" + Configuration["Authentication:KeycloakAuthentication:Realm"];
                options.TokenValidationParameters = new Microsoft.IdentityModel.Tokens.TokenValidationParameters
                {
                    ValidAudiences = new string[] { "curl", "financeApplication", "accountingApplication", "swagger"}
                };
                options.RequireHttpsMetadata = false; //for test only!
                options.SaveToken = true;
                options.Validate();

            });

And in Configure:

app.UseAuthentication();

You can access your token later with IHttpContextAccessor httpContextAccessor, for example:

public KeycloakAuthorizationRequirementHandler(IConfiguration config,
            IHttpContextAccessor httpContextAccessor,
            IMemoryCache memoryCache)
        {
            _config = config;
            _httpContextAccessor = httpContextAccessor;
            _memoryCache = memoryCache;
        }

//get accessToken

var accessToken = _httpContextAccessor.HttpContext.GetTokenAsync("access_token");

_httpContextAccessor.HttpContext.Items["username"] = username;

Tell me how it goes.