Logging

In SharwAPI plugin development, logging is an important aspect.

Usage Principles

Since the main program has already taken over the entire system's logging via builder.Host.UseSerilog(), plugins do not need any special configuration, nor do they need to reference the Serilog package.

Plugins only need to follow the standard hosting pattern and use the ILogger<T> interface. Logs will automatically flow to your configured console and files.

Example Code

Suppose you want to log in TokenAuthMiddleware:

using Microsoft.Extensions.Logging; // Must reference this namespace, it is the core of .NET Core logging abstraction

public class TokenAuthMiddleware
{
    private readonly RequestDelegate _next;
    
    // 1. Define Logger Field
    // T in ILogger<T> (here TokenAuthMiddleware) is used to mark the Category of the log source.
    // This way, when viewing logs, we can clearly know which class generated this log.
    private readonly ILogger<TokenAuthMiddleware> _logger; 

    // 2. Request ILogger<T> in Constructor
    // The main program will automatically pass the configured Logger instance here.
    public TokenAuthMiddleware(RequestDelegate next, ILogger<TokenAuthMiddleware> logger)
    {
        _next = next;
        _logger = logger;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        // 3. Log (Supports Structured Logging Arguments)
        // Note: The placeholder {Path} is used here instead of string concatenation.
        // Serilog will capture the property name "Path" and property value context.Request.Path, saving it as structured data.
        // This performs better and is easier to search than _logger.LogInformation("Checking token for path: " + context.Request.Path).
        _logger.LogInformation("Checking token for path: {Path}", context.Request.Path);

        if (!IsTokenValid(context))
        {
            // LogWarning is used to log unexpected issues that do not crash the program.
            // Also uses structured logging to record the IP address for subsequent analysis of attack sources.
            _logger.LogWarning("Invalid token from IP: {IpAddress}", context.Connection.RemoteIpAddress);
            // ...
        }

        await _next(context);
    }
}

Why This Approach?

• Decoupling: The plugin only depends on standard interfaces (Microsoft.Extensions.Logging) and does not depend on a specific logging library (Serilog).
• Unified Management: Log format, file path, and rolling policy are all controlled uniformly by the host program in appsettings.json, and the plugin does not need to care about them.
• Structured: Although the code writes {Path}, Serilog will save it as structured data, facilitating subsequent queries.