Normally authentication handlers for external providers are added into your IdentityServer using AddAuthentication() and AddOpenIdConnect(). This is fine for a handful of schemes, but the authentication handler architecture in ASP.NET Core was not designed for dozens or more statically registered in the DI system. At some point you will incur a performance penalty for having too many. Also, as you need to add or change this configuration you will need to re-compile and re-run your startup code for those changes to take effect.
Duende IdentityServer provides support for dynamic configuration of OpenID Connect providers loaded from a store. This is designed to address the performance concern as well as allowing changes to the configuration to a running server.
The identity provider store can be used to query the database containing the dynamic providers.
/// <summary>
/// Interface to model storage of identity providers.
/// </summary>
public interface IIdentityProviderStore
{
/// <summary>
/// Gets all identity providers name.
/// </summary>
Task<IEnumerable<IdentityProviderName>> GetAllSchemeNamesAsync();
// other APIs omitted
}
These results can then be used to populate the list of options presented to the user on the login page.
This API is deliberatly separate to the IAuthenticationSchemeProvider provided by ASP.NET Core, which returns the list of statically configured providers (from Startup.cs). This allows the developer to have more control over the customization on the login page (e.g. there might be hundreds or thousands of dynamic providers, and therefore you would not want them displayed on the login page, but you might have a few social providers statically configured that you would want to display).
Here is an example of how the IdentityServer Quickstart UI uses both interfaces to then present a merged and unified list to the end user:
var schemes = await _schemeProvider.GetAllSchemesAsync();
var providers = schemes
.Where(x => x.DisplayName != null)
.Select(x => new ExternalProvider
{
DisplayName = x.DisplayName ?? x.Name,
AuthenticationScheme = x.Name
}).ToList();
var dyanmicSchemes = (await _identityProviderStore.GetAllSchemeNamesAsync())
.Where(x => x.Enabled)
.Select(x => new ExternalProvider
{
AuthenticationScheme = x.Scheme,
DisplayName = x.DisplayName
});
providers.AddRange(dyanmicSchemes);
To use the dynamic providers feature an identity provider store must be provided that will load model data for the OIDC identity provider to be used. If you’re using the Entity Framework Integration then this is implemented for you.
The configuration data for the OIDC provider is used to assign the configuration on the ASP.NET Core OpenID Connect Options class, much like you would if you were to statically configure the options when using AddOpenIdConnect(). The identity provider model documentation provides details for the model properties and how they are mapped to the options.
If it is needed to further customize the OpenIdConnectOptions, you can register in the DI system an instance of IConfigureNamedOptions<OpenIdConnectOptions>. For example:
public class CustomConfig : IConfigureNamedOptions<OpenIdConnectOptions>
{
public void Configure(string name, OpenIdConnectOptions options)
{
if (name == "MyScheme")
{
options.ClaimActions.MapAll();
}
}
public void Configure(OpenIdConnectOptions options)
{
}
}
And to register this in the DI system:
public void ConfigureServices(IServiceCollection services)
{
services.ConfigureOptions<CustomConfig>();
}
If your customization of the OpenIdConnectOptions requires per-provider data that you are storing on the OidcProvider, then we provide an abstraction for the IConfigureNamedOptions<OpenIdConnectOptions>. This abstraction requires your code to derive from ConfigureAuthenticationOptions<OpenIdConnectOptions, OidcProvider> (rather than IConfigureNamedOptions<OpenIdConnectOptions>). For exmaple:
class CustomOidcConfigureOptions : ConfigureAuthenticationOptions<OpenIdConnectOptions, OidcProvider>
{
public CustomOidcConfigureOptions(IHttpContextAccessor httpContextAccessor) : base(httpContextAccessor)
{
}
protected override void Configure(ConfigureAuthenticationContext<OpenIdConnectOptions, OidcProvider> context)
{
var oidcProvider = context.IdentityProvider;
var oidcOptions = context.AuthenticationOptions;
// TODO: configure oidcOptions with values from oidcProvider
}
}
The above class would need to be configured in DI (as before):
public void Configure(IServiceCollection services)
{
services.ConfigureOptions<CustomOidcConfigureOptions>();
}
As part of the architecture of the dynamic providers feature, the various callback paths are required and are automatically set to follow a convention. The convention of these paths follows the form of ~/federation/{scheme}/{suffix}.
These are three paths that are set on the OpenIdConnectOptions:
This means for your IdentityServer running at “https://sample.duendesoftware.com” and an OIDC identity provider whose scheme is “idp1”, your client configuration with the external OIDC identity provider would be:
The DynamicProviderOptions is a new options class in the IdentityServer options object model. It provides shared settings for the dynamic identity providers feature.