问题描述

在Azure Function代码中，有默认的ILogger对象来记录函数的日志，如果函数引用了一些静态对象，是否有办法使用这个默认的ILogger对象来记录日志呢？

using System.Net;
using Microsoft.Azure.Functions.Worker;
using Microsoft.Azure.Functions.Worker.Http;
using Microsoft.Extensions.Logging;

namespace Company.Function
{
    public class HttpTrigger1
    {
        private readonly ILogger _logger;

        public HttpTrigger1(ILoggerFactory loggerFactory)
        {
            _logger = loggerFactory.CreateLogger<HttpTrigger1>();
        }

        [Function("HttpTrigger1")]
        public HttpResponseData Run([HttpTrigger(AuthorizationLevel.Function, "get", "post")] HttpRequestData req)
        {
            _logger.LogInformation("C# HTTP trigger function processed a request.");

            var response = req.CreateResponse(HttpStatusCode.OK);
            response.Headers.Add("Content-Type", "text/plain; charset=utf-8");

            response.WriteString("Welcome to Azure Functions!");

            return response;
        }
    }
}

问题解答

可以的，有两种方式来实现：方式一是把_logger对象作为参数传递给静态方法，方式二是自定义一个静态ILogger 对象，然后在静态方法中使用。

方式一：把_logger对象作为参数传递

示例代码：

        [Function("Function1")]
        public HttpResponseData Run([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post")] HttpRequestData req)
        {
   ... 

            //Call Static Fun  without _logger
            GetLocalStaticFun();
            //Call static Fun with _logger 
            GetLocalStaticFun(_logger);
   ... 
        }

        public static void GetLocalStaticFun(ILogger _sublogger = null)
        {
            //TODO Logic process 
            if (_sublogger != null)
            {
                _sublogger.LogInformation("this is static fucntion for testing...LogInformation. @2023/10/25");
            }
        }

测试效果：

方式二：定义静态ILogger对象

示例代码：

        static ILoggerFactory _staticLoggerFactory = LoggerFactory.Create(builder =>
             {
                 builder
                 .AddFilter("Microsoft", LogLevel.Warning)
                 .AddFilter("System", LogLevel.Warning)
                 .AddConsole();
             });

        static ILogger _staticloger = _staticLoggerFactory.CreateLogger<Function1>();


        public static void GetStaticLogFun()
        {
            _staticloger.LogInformation("Example log message form static class");
            _staticloger.LogError("Example error message form static class");

        }

注：以此种方式记录的日志，当部署到Azure Function App云服务后，通过在高级工具(kudu)站点查看日志时，与正常的日志不同，在与函数名同名的Folder中，而是在Host Folder中(C:\home\LogFiles\Application\Functions\Host)。

参考资料

ILoggerFactory static create： https://learn.microsoft.com/en-us/dotnet/core/extensions/logging?tabs=command-line#non-host-console-app