Identity Server 4 And Client Credentials Grant Sample
Identity Endpoints

Identity server is provide a series endpoints. We will by using them communicate with identity server. We will include Http client then request token and info from server. Below I tried to explain some of the “endpoints” that I think significant. Also you can find out more in here

Discovery Endpoint

Discovery endpoint is a information request about auth server. its response json string to us. Has many info inside of discovery. Such as base url, supported scopes, claims, grant types and response types. Below url is discovery endpoint.

https://base-url/.well-known/openid-configuration

User Info Endpoint

We can get information about user idenity from auth server. We need token for this.Also when we get information, some data will be missing. We can set this up in client services.

GET https://base-url/connect/userinfo

Authorization: Bearer <access_token>

Introspection Endpoint

This time we are checking to token authorize on API as client. of course we’re require token and authorization type. Server is send back response to client as true or false.

POST https://base-url/connect/introspect

Quickstart UI

A sample UI is exist in identityServer4 github page. I will by using this UI i contunie this project. For this reason required including in the auth server for those who will read the entire blog. You easily can include with powershell.You can visit the github repository for more details in here.

Creating Solution Project

First of all we are need a project template. I will use a API, 2 Client and a AuthServer as web application project in my solution. I will tell the whole scenario through these projects. You can examine structure in the repository.

Client Credentials Grant Application

Let’s remember again. What is Client Credentials Grant? We were doing client authentication request to auth server. Then it sending back with Access Token. Hereunder let’s create a scenario. We have two client and two API . And we define identity allowance for APIs. such as read or write. as example, client1 can read to API1 and client2 can write to API2. Apart from these, clients cannot access to apıs.

1. Configure Sources

We will work in memorylable. For this reason we creating a named Config.cs in Auth server project. We define clients, resources and scopes in this class. Actually this code part is so understandable. But still let's explain. We are defining for middleware services. And we are create ApiScope list. Then we defining resource for APIs. And clients...

Scopes

public static IEnumerable<ApiScope> GerApiScopes()

{

return new List<ApiScope>

{

new ApiScope("api1.read","read permission for API 1"),

new ApiScope("api2.write","write permission for API 2"),

};

}

API Resources

public static IEnumerable<ApiResource> GetApiResource()

{

return new List<ApiResource>

{

new ApiResource("resource_api1"){Scopes = {"api1.read"}},

new ApiResource("resource_api2"){Scopes = {"api2.write"}}

};

}

Clients

public static IEnumerable<Client> GetClients()

{

return new List<Client>()

{

new Client()

{

ClientId = "Client1",

ClientName = "Client 1 API app",

ClientSecrets = new[] {new Secret("secret".Sha256()) },

AllowedGrantTypes = GrantTypes.ClientCredentials,

AllowedScopes = {"api1.read"}

},

new Client()

{

ClientId = "Client2",

ClientName = "Client 2 API app",

ClientSecrets = new[] {new Secret("secret".Sha256()) },

AllowedGrantTypes = GrantTypes.ClientCredentials,

AllowedScopes = {"api2.write"}

},

}

};

}

We defined some resource. On next, there is introducing resources to identity server. We will add service and middleware layer. Also require define grant type for identity server in sevices.

services.AddIdentityServer()

.AddInMemoryApiResources(Config.GerApiResource())

.AddInMemoryApiScopes(Config.GerApiScopes())

.AddInMemoryClients(Config.GetClients())

.AddDeveloperSigningCredential();

Note :It’s must define after from authorization

app.UseIdentityServer();

2. Client Side Processes

in the next, require to realizationing of client credentials grant algorithm. I tried explain process by process in below. I hope it’s apprehensible.

public async Task<IActionResult> Index()

{

//require http client object for requests

HttpClient httpClient = new HttpClient();

//we're gets information about auth server such as scopes and base url

var discovery = await httpClient.GetDiscoveryDocumentAsync("https://localhost:5001");



if (discovery.IsError){/*Logging*/} ClientCredentialsTokenRequest clientCredentialsTokenRequest = new ClientCredentialsTokenRequest();

clientCredentialsTokenRequest.ClientId = "Client1";

clientCredentialsTokenRequest.ClientSecret = "secret";

//We define address (https://base-ulr/connect/token) where we will receive token

clientCredentialsTokenRequest.Address = discovery.TokenEndpoint;

//And sending request

var token = await httpClient.RequestClientCredentialsTokenAsync(clientCredentialsTokenRequest); if (token.IsError){/*Logging*/} //at now we have a access token. We can request to api. Also require authorization type in header

httpClient.SetBearerToken(token.AccessToken); var response = await httpClient.GetAsync("https://localhost:5016/api/product/getproducts");

List<Product> products = new List<Product>();

if (response.IsSuccessStatusCode)

{

var content = await response.Content.ReadAsStringAsync();

products = JsonConvert.DeserializeObject<List<Product>>(content);

}

else{/*Logging*/} return View(products);

}

3. API Side Processes

Now, We must inform to API project about resources lastly. But after we must include Jwt Token nutget package. Also since it’s the middleware level we are adding app.UseAuthentication() to configure method. Footnote, authentitcation must be after authorize.

public void ConfigureServices(IServiceCollection services)

{

services.AddAuthentication(/*NormalUser*/JwtBearerDefaults.AuthenticationScheme)

.AddJwtBearer(/*NormalUser*/JwtBearerDefaults.AuthenticationScheme, opt =>

{

opt.Authority = "https://localhost:5001";

opt.Audience = "resource_api1";

});

services.AddAuthorization(opts =>

{

opts.AddPolicy("ReadProduct", policy =>

{

policy.RequireClaim("scope", "api1.read");

});

opts.AddPolicy("UpdateOrCreate", policy =>

{

policy.RequireClaim("scope", new [] {"api1.update","api1.create"});

});

});

services.AddControllers();

}

in contorller, we can use authorize attribute for action. Or can be direct controller level. if request is not authorized, identity server will return unauthorized status.

[Authorize(Policy = "ReadProduct")]

public IActionResult GetProducts()

{

return Ok(new List<Product>());

}

Result

We learned many topic about identity server 4. And we solved an example according to the scenario. Now we can code system using client credentials flow with identity server. I didnt mention so about another flows. But you can find many article about its in internet.Thank you for reading. Good luck with coding.

Source

https://www.gencayyildiz.com/blog/identityserver4-yazi-serisi-8-authorization-code-grantflow/

https://tools.ietf.org/html/rfc6749

https://identityserver4.readthedocs.io/en/latest/index.html

Contact

Muhammet İkbal KAZANCI — LinkedIn — mi.kazanci@hotmail.com
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['Dotnet', 'Csharp', 'Identityserver4', 'Software', 'Software Development']