Setup - Aguafrommars/DynamicAuthProviders GitHub Wiki

In your Startup ConfigureServices method, add the following:

/** Add dynamic management **/

// Add the context to store schemes configurations.
// The context can be any kind of DbContext having a DbSet<TSchemeDefinition>
// where TSchemeDefinition is of type SchemeDefinition or derived.
services.AddDbContext<SchemeDbContext>(options =>
{
    options.UseSqlServer(Configuration.GetConnectionString("Default"));
}); 

// Add authentication
var authBuilder = services
    .AddAuthentication();

// Add the magic
var dynamicBuilder = authBuilder
    .AddDynamic<SchemeDefinition>()
    .AddEntityFrameworkStore<SchemeDbContext>();

// Add providers managed dynamically
dynamicBuilder.AddGoogle()
    .AddOAuth("Github", "Github", options =>
    {
        // You can define default configuration for managed handlers.
        options.AuthorizationEndpoint = "https://github.com/login/oauth/authorize";
        options.TokenEndpoint = "https://github.com/login/oauth/access_token";
        options.UserInformationEndpoint = "https://api.github.com/user";
        options.ClaimsIssuer = "OAuth2-Github";
        // Retrieving user information is unique to each provider.
        options.ClaimActions.MapJsonKey(ClaimTypes.NameIdentifier, "id");
        options.ClaimActions.MapJsonKey(ClaimTypes.Name, "login");
        options.ClaimActions.MapJsonKey("urn:github:name", "name");
        options.ClaimActions.MapJsonKey(ClaimTypes.Email, "email", ClaimValueTypes.Email);
        options.ClaimActions.MapJsonKey("urn:github:url", "url");
        options.Events = new OAuthEvents
        {
            OnCreatingTicket = async context =>
            {
                // Get the GitHub user
                var request = new HttpRequestMessage(HttpMethod.Get, context.Options.UserInformationEndpoint);
                request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", context.AccessToken);
                request.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
                // A user-agent header is required by GitHub. See (https://developer.github.com/v3/#user-agent-required)
                request.Headers.UserAgent.Add(new ProductInfoHeaderValue("DynamicAuthProviders-sample", "1.0.0"));

                var response = await context.Backchannel.SendAsync(request, context.HttpContext.RequestAborted);
                var content = await response.Content.ReadAsStringAsync();
                response.EnsureSuccessStatusCode();

                var user = JObject.Parse(content);

                context.RunClaimActions(user);
            }
        };
    }); 

And in the Configure method load the configuration with LoadDynamicAuthenticationConfiguration method:

    app.UseHttpsRedirection()
        .UseStaticFiles()
        .UseCookiePolicy()
        .UseAuthentication()
        .UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        })
        // load dynamyc authentication configuration from store
        .LoadDynamicAuthenticationConfiguration();