Newbie's practice 1: Logging and Configuration

README.md

Newbie's practice: Logging and Configuration

Remarks

Environment

• ASPNETCORE_ENVIRONMENT is used for environment varialble for ASP.net core. It is convention. Instead of that, I use similar one because it is console app.
• ?? operator can be used for default env variable.

Configuration

• A file can be a placeholder for Configuration.
• appsettings.json is just conventional setting name on .net core.
• Section can be selected by Configuration.GetSection("SectionName").

ServiceCollection and serviceProvider

• .net core provides default dependency injection container. So, we can utilize it.
• In this session, we can't say it is useful but just stick to it for next session.
• Dependency injection in ASP.NET Core should be useful resource.

Logging

• ServiceCollection helps us to add logging.
• Lambda expressions for logging builder can be used.
• Please check LogLevel on appsettings.Development.json.
• You can create logger from loggerFactory.
• In CreateLogger<Program>(), Program is category name. Usually class name is used.
• Understanding log level is important.
• Without ((IDisposable) serviceProvider)?.Dispose();, you can't see output at this moment. Please check here.

Reference

• https://andrewlock.net/creating-a-rolling-file-logging-provider-for-asp-net-core-2-0/
• https://andrewlock.net/using-dependency-injection-in-a-net-core-console-application/

appsettings.Development.json

{
    "Logging": {
        "Console": {
            "IncludeScopes": false,
            "LogLevel": {
                "Default": "Trace",
                "LoggerDemo.Program": "Information"
            }
        },
        "LogLevel": {
            "Default": "Debug"
        }
    }
}

LoggerDemo.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>netcoreapp2.1</TargetFramework>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Extensions.Configuration" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Microsoft.Extensions.Configuration.JSON" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="2.1.1" />
    <PackageReference Include="Microsoft.Extensions.Logging" Version="2.2.0-preview1-35029" />
    <PackageReference Include="Microsoft.Extensions.Logging.Console" Version="2.2.0-preview1-35029" />
  </ItemGroup>

</Project>

Program.cs

using System;
using System.IO;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace LoggerDemo
{
    public class Program
    {
        public static void Main(string[] args)
        {
            string env = Environment.GetEnvironmentVariable("DOTNETCORE_ENVIRONMENT") ?? "Development";

            var configurationBuilder = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env}.json", optional: false, reloadOnChange: true);
            var Configuration = configurationBuilder.Build();

            var serviceCollection = new ServiceCollection()
                .AddLogging(builder => 
                {
                    builder.AddConfiguration(Configuration.GetSection("Logging"));
                    builder.AddConsole();
                });
            var serviceProvider = serviceCollection.BuildServiceProvider();

            var loggerFactory = serviceProvider.GetService<ILoggerFactory>();
            var logger = loggerFactory.CreateLogger<Program>();

            logger.LogTrace("Trace");
            logger.LogDebug("Debug");
            logger.LogInformation("Information");
            logger.LogWarning("Warning");
            logger.LogError("Error");

            ((IDisposable) serviceProvider)?.Dispose();
        }
    }
}

Next topic (maybe):

file logging with serilog

• https://andrewlock.net/creating-a-rolling-file-logging-provider-for-asp-net-core-2-0/
• https://nblumhardt.com/2017/08/use-serilog/

Next topic (maybe):

logging on AWS CloudWatch:

• https://github.com/aws/aws-logging-dotnet