In Swagger UI, how can I remove the padlock icon from "anonymous" methods?

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05-09-2024

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Removing the Padlock Icon from Anonymous Endpoints in Swagger UI

Swagger UI provides a visual representation of your API documentation, including authentication requirements. While this is generally helpful, it can be confusing to see a padlock icon on endpoints that don't actually need authorization. This article explores how to remove the padlock icon from "anonymous" methods in Swagger UI, using a .NET Core 2.1 example with JWT authentication.

The Problem

As described in the Stack Overflow post https://stackoverflow.com/questions/51477359/swagger-ui-show-padlock-icon-even-when-endpoint-is-anonymous, a developer encountered an issue where Swagger UI displayed a padlock icon for all endpoints, even those explicitly marked as [AllowAnonymous]. This is misleading and can lead to user confusion.

The Solution

The solution lies in using Swagger's OperationFilter interface. This interface allows you to modify Swagger's output, including the authentication information for each endpoint. Here's how to implement it:

1. Create an Operation Filter

   using Swashbuckle.AspNetCore.Swagger;
   using Swashbuckle.AspNetCore.SwaggerGen;
   
   public class AllowAnonymousOperationFilter : IOperationFilter
   {
       public void Apply(Operation operation, OperationFilterContext context)
       {
           var hasAllowAnonymousAttribute = context.MethodInfo.GetCustomAttributes(true).Any(a => a.GetType() == typeof(AllowAnonymousAttribute));
   
           if (hasAllowAnonymousAttribute)
           {
               // Remove the 'security' property from the operation if it's marked as AllowAnonymous.
               operation.Security = new List<SecurityRequirement>();
           }
       }
   }
   

2. Register the Operation Filter

   In your Startup.cs file, add the following code within the ConfigureServices method:

   services.AddSwaggerGen(c =>
   {
       // Other Swagger configuration...
   
       // Register the custom filter.
       c.OperationFilter<AllowAnonymousOperationFilter>(); 
   });
   

Explanation

The AllowAnonymousOperationFilter inspects each operation (endpoint) and checks if it has the [AllowAnonymous] attribute. If present, it removes the security property from the operation's definition. This property is what Swagger uses to determine if authentication is required. By removing it, the padlock icon is effectively hidden for anonymous endpoints.

Additional Considerations

• Multiple Authentication Schemes: If you have multiple authentication schemes configured (e.g., JWT and Basic Authentication), you might need to modify the filter to target specific schemes based on the endpoint's authorization requirements.
• Custom Attributes: You can customize the attribute used to identify anonymous endpoints. If you prefer to use a different attribute, adjust the filter accordingly.

Summary

By implementing a custom OperationFilter, you can control how Swagger UI displays authentication information for your API endpoints. This allows you to ensure that the user interface accurately reflects the actual authorization requirements of your API, improving clarity and reducing confusion.