How to get IOptions in ConfigureServices method or pass IOptions into extension method? - asp.net-web-api

Question

I'm developing asp .net core web api 2.1 app.
I add JWT authentication service as an extension method in static class:
public static class AuthenticationMiddleware
{
public static IServiceCollection AddJwtAuthentication(this IServiceCollection services, string issuer, string key)
{
services
.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddJwtBearer(options =>
{
options.TokenValidationParameters = new TokenValidationParameters
{
// validate the server that created that token
ValidateIssuer = true,
// ensure that the recipient of the token is authorized to receive it
ValidateAudience = true,
// check that the token is not expired and that the signing key of the issuer is valid
ValidateLifetime = true,
// verify that the key used to sign the incoming token is part of a list of trusted keys
ValidateIssuerSigningKey = true,
ValidIssuer = issuer,
ValidAudience = issuer,
IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(key))
};
});
return services;
}
}
which I use in ConfigureServices method of Startup class like this:
public void ConfigureServices(IServiceCollection services)
{
// adding some services omitted here
services.AddJwtAuthentication(Configuration["Jwt:Issuer"], Configuration["Jwt:Key"]);
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
Now, I have a requirement to use IOptions pattern to get JWT authentication data from appsettings.json
How can I get IOptions in ConfigureServices method to pass issuer and key into extension method? Or how to pass IOptions to extension method?

Answer 1

For binding data from appsettings.json to Model, you could follow steps below:
Appsettings.json content
{
"Logging": {
"IncludeScopes": false,
"LogLevel": {
"Default": "Warning"
}
},
"JWT": {
"Issuer": "I",
"Key": "K"
}
}
JWT Options
public class JwtOptions
{
public string Issuer { get; set; }
public string Key { get; set; }
}
Startup.cs
public void ConfigureServices(IServiceCollection services)
{
services.Configure<JwtOptions>(Configuration.GetSection("JWT"));
var serviceProvider = services.BuildServiceProvider();
var opt = serviceProvider.GetRequiredService<IOptions<JwtOptions>>().Value;
services.AddJwtAuthentication(opt.Issuer, opt.Key);
services.AddMvc();
}
One more option to pass JwtOptions directly.
public void ConfigureServices(IServiceCollection services)
{
services.Configure<JwtOptions>(Configuration.GetSection("JWT"));
var serviceProvider = services.BuildServiceProvider();
var opt = serviceProvider.GetRequiredService<IOptions<JwtOptions>>().Value;
services.AddJwtAuthentication(opt);
services.AddMvc();
}
Change the extension method.
public static IServiceCollection AddJwtAuthentication(this IServiceCollection services, JwtOptions opt)

Answer 2

One other option is to bind the configurations to a class with the Bind() extension. (IMO this a more clean solution then the IOptions)
public class JwtKeys
{
public string Issuer { get; set; }
public string Key { get; set; }
}
public void ConfigureServices(IServiceCollection services)
{
var jwtKeys = new JwtKeys();
Configuration.GetSection("JWT").Bind(JwtKeys);
services.AddJwtAuthentication(jwtKeys);
}
public static IServiceCollection AddJwtAuthentication(this IServiceCollection services, JwtKeys jwtKeys)
{....}
Then if you need the JwtKeys settings some other place in the solution, just register the class on the collection and inject it where needed
services.AddSingleton(jwtKeys);

Answer 3

You can add your options to DI container in Startup class like this:
public class JwtOptions
{
public string Issuer { get; set; }
public string Key { get; set; }
}
public void ConfigureService(IServiceCollection services)
{
services.AddOptions();
services.Configure<JwtOptions>(Configuration.GetSection("Jwt"));
}
Now you can use this options, in a configure stage, or in an extension method:
public void Configure(IApplicationBuilder app)
{
var options = app.ApplicationServices.GetService<IOptions<JwtOptions>();
// write your own code
}