.net Core Access appsettings.json When Configuring a Different Configuration Provider

Question

I'm just getting started with .net Core 2.1 and I have written a custom ConfigurationProvider that loads my sensitive configuration from a separate file. This works great with a hard-coded path but I also want the location of the file to be stored in configuration. If I try to access the appsettings config during the setup of my provider the values aren't there. Presumably this is because I am in the configuration phase still. Is there a way of accessing them or failing that is there a way to add another config provider inside Startup.cs instead of Program.cs?

This is what I am trying to do:

public static IWebHostBuilder CreateWebHostBuilder(string[] args)
{
    return WebHost.CreateDefaultBuilder(args)
                    .ConfigureLogging((hostingContext, logging) =>
                    {
                        logging.ClearProviders();
                        logging.AddConsole();
                        logging.AddFile(opts =>
                        {
                            hostingContext.Configuration.GetSection("FileLoggerOptions").Bind(opts);
                        });
                    })
                    .ConfigureAppConfiguration((hostingContext, config) =>
                    {
                        config.SetBasePath(hostingContext.HostingEnvironment.ContentRootPath);
                        config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
                        config.AddJsonFile($"appsettings.{hostingContext.HostingEnvironment.EnvironmentName}.json", optional: true);
                        config.AddEncryptedFile(hostingContext.Configuration["SecureSettingsFile"], true, true);
                    })
                    .UseStartup<Startup>();
}

As you can see I am able to access the config in the logging config but not the app config. My provider is the AddEncryptedFile bit and hostingContext.Configuration["SecureSettingsFile"] should read the value from appsettings.json.

The only configuration available at this stage is Environment variables and I don't really want to use those as the server has about 30 websites on it.

Is what I am trying do possible or will I have to use an Environment variable or store my encrypted config in the same location as my website?

thanks

Answer 1

You'll need to use a ConfigurationBuilder to initially just read appsettings.json, and use the output of the builder to do your full configuration. Something like this:

.ConfigureAppConfiguration((hostingContext, config) =>
{
    var baseConfig = new ConfigurationBuilder()
        .SetBasePath(Directory.GetCurrentDirectory())
        .AddJsonFile("appsettings.json")
        .Build();
    var secureSettingsFile = baseConfig.GetValue<string>("SecureSettingsFile");

    /* ... */
    config.AddEncryptedFile(secureSettingsFile, true, true);
})