dahlbyk / SlackLogger

A simple and configurable logger for ASP.NET Core projects that logs to Slack

SlackLogger

A simple and configurable logger for .NET Core projects that logs to Slack.

SlackLogger will post formatted log messages at the desired level to a specified channel or person.

Usage

Works with .NET Core >= 2.0. Reference package SlackLogger >= 2.0.

To use with .NET Core 1.0 reference SlackLogger version < 2.0 (docs here)

Program.cs

  public static IWebHost CreateDefaultBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.AddSlack(options =>
                    {
                        options.WebhookUrl = "https://hooks.slack.com/services/ABC123FGH321QWERTYUICAZzDJBG3sehHH7scclYdDxj";
                    });

                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });

or in a console application: Program.cs

      IConfiguration configuration =
                new ConfigurationBuilder()
                    .AddJsonFile($"{Directory.GetCurrentDirectory()}/appsettings.json", false, true)
                    .Build();
            
      var serviceProvider = new ServiceCollection()
            .AddSingleton(configuration)
            .AddLogging(builder =>
        {
            builder.AddConfiguration(Configuration.GetSection("Logging"));
            builder.AddSlack(options =>
            {
                options.WebhookUrl =
                    "https://hooks.slack.com/services/ABC123FGH321QWERTYUICAZzDJBG3sehHH7scclYdDxj";
            });
        }).BuildServiceProvider();
    
    
        var logger = serviceProvider.GetService<ILogger<Program>>();

Configuration

The logger has a number of optional settings:

logging.AddSlack(options =>
{
     options.WebhookUrl = "https://hooks.slack.com/services/ABC123FGH321QWERTYUICAZzDJBG3sehHH7scclYdDxj";
     options.LogLevel = LogLevel.Information;
     options.NotificationLevel = LogLevel.None;
     options.Environment = env.EnvironmentName;
     options.ApplicationName = "My application";
     options.Channel = "#mychannel";
     options.ChannelCritical = "#mychannel-critical";
     options.SanitizeOutputFunction = output => Regex.Replace(output, "@[^\\.@-]", "");
     options.UserName = "SlackLogger";
});
            

Channel Overrides the channel or person that is configured in the Slack webhook.

ChannelCritical, ChannelError, ChannelWarning, ChannelInformation, ChannelDebug, ChannelTrace Overrides the Channel setting for the specified log level. If any of these are unset, it will fall back to the Channel value.

LogLevel Sets the minimum log level used. Defaults to Warning.

NotificationLevel Sets the minimum log level that causes notifications on Slack (using @channel). Defaults to Error.

ApplicationName Prints the name of the current hosting environment in each log statement, if set. Defaults to the entry assembly name.

EnvironmentName Prints the name of the current hosting environment in each log statement, if set. Defaults to env variable ASPNETCORE_ENVIRONMENT, if set, otherwise it is empty.

SanitizeOutputFunction Can be used to modify the messages (including stack traces) before they are logged. Used if one is concerned that certain details are too sensitive to be posted to Slack.

UserName Sets the username sent to Slack. Defaults to SlackLogger. Set it to null, if you want to use the default webhook username.

Configure using ConfigurationProvider

SlackLogger can be completely or partially configured using a configuration provider:

.ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddSlack();
                })

appsettings.json:

"Logging": {
    "Slack": {
        "WebhookUrl": "https://hooks.slack.com/services/ABC123FGH321QWERTYUICAZzDJBG3sehHH7scclYdDxj",
        "LogLevel": "Information",
        "NotificationLevel": "Error"
    }
}

If the same property is set both in code and in the configuration provider, the value from the configuration provider is used.

Filtering namespaces

The logger filters log statements from different part of the code using namespaces in the same way as the default loggers, if that section of the configuration is provided:

public IConfigurationRoot Configuration { get; set; }

...

.ConfigureLogging((hostingContext, logging) =>
                {
                    logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
                    logging.AddSlack();
                })                

appsettings.json:

"Logging": {
    "LogLevel": {
        "Default": "Debug",
        "System": "Information",
        "Microsoft": "Warning"
    },
    "Slack": {
        "WebhookUrl": "https://hooks.slack.com/services/ABC123FGH321QWERTYUICAZzDJBG3sehHH7scclYdDxj"
    }
},