Empowering Your GraphQL API: Authorizing Subscriptions in HotChocolate
HotChocolate, a powerful GraphQL server framework for .NET, allows developers to create robust APIs quickly. However, as your API grows, securing sensitive data and restricting access to specific features becomes crucial. This is where authorization comes into play. While implementing authorization for queries and mutations is straightforward, securing subscriptions requires a deeper understanding.
This article will guide you through the process of authorizing subscriptions in HotChocolate, ensuring your real-time data streams are protected.
The Problem: Securing Real-Time Data
Imagine a scenario where you have a real-time dashboard displaying live user activity on your application. You might want to restrict access to this data based on user roles, only allowing administrators to view it. Traditional authorization methods might not suffice for subscriptions, as they handle requests one at a time.
Scenario:
Let's say you have a subscription that broadcasts new user registrations:
public class Mutation
{
public async Task<User> RegisterUserAsync(
[Service] IUserRegistrationService registrationService,
UserRegistrationInput input)
{
return await registrationService.RegisterUserAsync(input);
}
}
public class Subscription
{
[Subscribe]
public Task<User> OnUserRegistered(
[Service] IUserRegistrationService registrationService)
{
return registrationService.ObserveNewUsers();
}
}
Without proper authorization, any authenticated user could subscribe to this event and receive sensitive information.
Solution: Leveraging Authorization Middleware
HotChocolate offers powerful middleware mechanisms to intercept and control requests. We can leverage this to authorize subscription requests before they reach the resolver:
public class Startup
{
// ... other configurations ...
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseRouting()
.UseMiddleware<AuthorizationMiddleware>()
.UseEndpoints(endpoints =>
{
endpoints.MapGraphQL();
});
}
public void ConfigureServices(IServiceCollection services)
{
// ... other services ...
services.AddAuthorizationCore()
.AddAuthorization(options =>
{
options.AddPolicy("AdminOnly", policy => policy.RequireRole("Admin"));
});
services.AddGraphQLServer()
.AddQueryType<Query>()
.AddMutationType<Mutation>()
.AddSubscriptionType<Subscription>();
}
}
public class AuthorizationMiddleware
{
private readonly RequestDelegate _next;
public AuthorizationMiddleware(RequestDelegate next)
{
_next = next;
}
public async Task InvokeAsync(HttpContext context, IAuthorizationService authorizationService)
{
// Fetch the current user
var user = context.User;
// Get the subscription name from the GraphQL request
var subscriptionName = context.Request.Path.Value.Split('/').Last();
// Define authorization policies for different subscriptions
var authorizationPolicy = subscriptionName switch
{
"OnUserRegistered" => "AdminOnly",
_ => null
};
// Check if authorization is required
if (authorizationPolicy != null)
{
// Authorize the user against the policy
var authorized = await authorizationService.AuthorizeAsync(user, authorizationPolicy);
if (!authorized.Succeeded)
{
// Handle unauthorized access - e.g., throw an error or redirect
context.Response.StatusCode = 403;
await context.Response.WriteAsync("Forbidden");
return;
}
}
// Proceed to the next middleware if authorized
await _next(context);
}
}
This code demonstrates how to use a custom middleware to enforce authorization rules for subscriptions based on user roles.
Additional Considerations
- Dynamic Authorization: You can use a more sophisticated approach to dynamically determine authorization rules based on factors like user roles, data context, or time-based restrictions.
- Real-Time Authentication: For real-time scenarios, consider using WebSocket authentication mechanisms like JWT or WebSockets with cookies.
Conclusion
Securing subscriptions in HotChocolate is essential for maintaining the integrity of your GraphQL API. By utilizing authorization middleware and carefully defining policies, you can ensure that only authorized clients have access to real-time data streams. Remember to consider dynamic authorization rules and secure authentication mechanisms to further strengthen your API security.
