Quick start with Serilog

Install the Stravaig.Configuration.Diagnostics.Serilog into your main project. (See Installing for details of installing the NuGet Package.

In your Startup class in the Configure or ConfigureServices method add the following:

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // Get the logger
    var logger = Log.ForContext<Startup>();

    // Define which keys contain secrets
    ConfigurationDiagnosticsOptions.SetupBy
        .Obfuscating.WithAsterisks()
        .And.MatchingConfigurationKeys.Where
        .KeyContains("AccessToken")
        .OrContains("ConnectionString")
        .And.MatchingConnectionStringKeys
        .Containing("Password")
        .AndFinally.ApplyOptions(ConfigurationDiagnosticsOptions.GlobalOptions);

    // Log the state of the configuration
    logger.LogProvidersAsInformation(Configuration);
    logger.LogConfigurationValuesAsInformation(Configuration);
    logger.LogConfigurationKeySourceAsInformation(Configuration, "ExtenalSystem:AccessToken");
    logger.LogAllConnectionStringsAsInformation(Configuration);

    // Set up other things...
}

The above setup up the diagnostics as follows

Any secret that is found is obfuscated by replacing the value with asterisks.
Any configuration key that contains “AccessToken” is considered a secret an will be obfuscated.
Any configuration key that contains “ConnectionString” is considered a secret.
When deconstructing connection strings, any part where the key contains “password”is considered a secret.

LogProvidersAsInformation

The output will look something like this:

info: Example.Startup[0]
  The following configuration providers were registered:
  Microsoft.Extensions.Configuration.ChainedConfigurationProvider
  JsonConfigurationProvider for 'appsettings.json' (Optional)
  JsonConfigurationProvider for 'appsettings.Development.json' (Optional)
  JsonConfigurationProvider for 'secrets.json' (Optional)
  EnvironmentVariablesConfigurationProvider
  CommandLineConfigurationProvider

LogConfigurationValuesAsInformation

The output will look something like this:

info: Example.Startup[0]
  The following values are available:
  Logging : (null)
  Logging:LogLevel : (null)
  Logging:LogLevel:Microsoft.Hosting.Lifetime : Information
  Logging:LogLevel:Microsoft : Warning
  Logging:LogLevel:Default : Information
  ExternalSystem : (null)
  ExternalSystem:Url : https://dev.some-external-system.com/api/v1
  ExternalSystem:AccessToken : *****************************
  ExtenalSystem : (null)
  ExtenalSystem:AccessToken : **************************************
  ENVIRONMENT : Development
  ConnectionStrings :
  ConnectionStrings:PostCodeLookupDatabase : **********************************************************************************************************************************************************************************
  ConnectionStrings:MainDatabase : ********************************************************************************************************
  ComSpec : C:\WINDOWS\system32\cmd.exe
  ASPNETCORE_URLS : https://localhost:5001;http://localhost:5000
  ASPNETCORE_ENVIRONMENT : Development
  applicationName : Example
  AllowedHosts : *

Note: I’ve omitted many of the environment variables from the above example.

One of the things you can see here, is that there is a typo in one of the configuration providers. If we had an issue with the ExternalSystem.AccessToken we can now see that somewhere it has been mistyped.

LogConfigurationKeySourceAsInformation

It is possible to trace where a specific key value came from, so in the case of the key with the typo, you can add a line to log out the source of that specific key/value.

logger.LogConfigurationKeySourceAsInformation(Configuration, "ExtenalSystem:AccessToken");

The output looks something like this:

info: Example.Startup[0]
  Provider sources for value of ExtenalSystem:AccessToken
  * Microsoft.Extensions.Configuration.ChainedConfigurationProvider ==> null
  * JsonConfigurationProvider for 'appsettings.json' (Optional) ==> null
  * JsonConfigurationProvider for 'appsettings.Development.json' (Optional) ==> null
  * JsonConfigurationProvider for 'secrets.json' (Optional) ==> **************************************
  * EnvironmentVariablesConfigurationProvider ==> null
  * CommandLineConfigurationProvider ==> null

As the only provider with a value for the key with the typo is the secrets.json file we can instantly tell where the issue is.

LogAllConnectionStringsAsInformation

Although we’ve designated that any configuration key that matches ConnectionString has a secret value associated with it, we can deconstruct a connection string into its component parts as they are not all secrets. This way you can examine a large portion of a connection string without exposing, for example, the password used to access it.

The output looks something like this:

info: Example.Startup[0]
  The following connection strings were found: MainDatabase, PostCodeLookupDatabase.
  Connection string (named MainDatabase) parameters:
   * server = dev.my-database-server.my-company.com
   * database = myDataBase
   * user id = myUsername
   * password = **********

  Connection string (named PostCodeLookupDatabase) parameters:
   * provider = MSOLEDBSQL
   * server = tcp:AvailabilityGroupListenerDnsName,1433
   * multisubnetfailover = Yes
   * applicationintent = ReadOnly
   * database = MyDB
   * integrated security = SSPI
   * connect timeout = 30