Lookup value from the appsettings.json or appsettings.Production.json and other configuration sources/overrides.

Introduced withNLog.Extensions.Logging 1.4.0 andNLog.Web.AspNetCore 4.8.0

${configsetting:item=String:default=String}

• item - Key in the config. Required. Use. for nested objects.
• Default - Default value if not present. Optional.

${configsetting} depends on Microsoft.Extensions.Configuration being loaded and available, so if usingUseNLog() orAddNLog() on HostBuilder then everything will work out-of-the-box.

But if needing to load NLog configuration early before HostBuilder is ready, then${configsetting} will not resolve the expected values, which might cause NLog Targets not using the expected configuration values. It is possible to setup${configsetting} manually for these situations.

NLog Fluent Setup usingLoadConfigurationFromAppSettings() fromNLog.Web.AspNetCore nuget-package:

varlogger=LogManager.Setup().LoadConfigurationFromAppSettings().GetCurrentClassLogger();

NLog Fluent Setup usingLoadConfigurationFromSection(() fromNLog.Extensions.Logging nuget-package:

IConfigurationRootconfig=newConfigurationBuilder().AddJsonFile(path:"AppSettings.json").Build();varlogger=LogManager.Setup().LoadConfigurationFromSection(config).GetCurrentClassLogger();

NLog v4 can perform manual registration like this withNLog.Extensions.Logging nuget-package:

IConfigurationRootconfig=newConfigurationBuilder().AddJsonFile(path:"AppSettings.json").Build();NLog.Extensions.Logging.ConfigSettingLayoutRenderer.DefaultConfiguration=config;

Example: appsettings.json:

{"Mode":"Prod","Options":{"StorageConnectionString":"UseDevelopmentStorage=true",    }}

Config Setting Lookup:

${configsetting:item=Mode} // renders "Prod"${configsetting:item=Options.StorageConnectionString} // renders "UseDevelopmentStorage=true"${configsetting:item=Options.TableName:default=MyTable} // renders "MyTable"

Config Setting Lookup Cached:

${configsetting:cached=True:item=Mode}

Noticeappsettings.json gives the ability to make environment-specific overrides (Ex.appsettings.Production.json). See alsoEnvironment-specific-NLog-Logging-Configuration