Created IConfigurationAccessor and add configuration by default.

src/Volo.Abp.AspNetCore/Microsoft/AspNetCore/Hosting/AbpHostingEnvironmentExtensions.cs

@@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Hosting
         {
             var builder = new ConfigurationBuilder()
                 .SetBasePath(env.ContentRootPath)
-                .AddJsonFile(fileName + ".json", optional: false, reloadOnChange: true)
+                .AddJsonFile(fileName + ".json", optional: true, reloadOnChange: true)
                 .AddJsonFile($"{fileName}.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
 
             return builder.Build();

src/Volo.Abp.AspNetCore/Microsoft/Extensions/DependencyInjection/AbpAspNetCoreServiceCollectionExtensions.cs

@@ -14,5 +14,12 @@ namespace Microsoft.Extensions.DependencyInjection
         {
             return services.GetHostingEnvironment().BuildConfiguration(fileName);
         }
+
+        public static IConfigurationRoot AddConfiguration(this IServiceCollection services, string fileName = "appsettings")
+        {
+            var configuration = services.BuildConfiguration(fileName);
+            services.AddConfiguration(configuration);
+            return configuration;
+        }
     }
 }

src/Volo.Abp.AspNetCore/Volo/Abp/AspNetCore/AbpAspNetCoreModule.cs

@@ -1,7 +1,5 @@
 using Microsoft.AspNetCore.Builder;
-using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.DependencyInjection.Extensions;
 using Volo.Abp.Modularity;
 using Volo.Abp.Security;
 using Volo.Abp.Threading;
@@ -19,6 +17,9 @@ namespace Volo.Abp.AspNetCore
             AddAspNetServices(services);
 
             services.AddObjectAccessor<IApplicationBuilder>();
+
+            services.AddConfiguration();
+
             services.AddAssemblyOf<AbpAspNetCoreModule>();
         }
 

src/Volo.Abp.Core/Microsoft/Extensions/DependencyInjection/ServiceCollectionConfigurationExtensions.cs

@@ -0,0 +1,19 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using Volo.Abp.Configuration;
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    public static class ServiceCollectionConfigurationExtensions
+    {
+        public static IServiceCollection AddConfiguration(this IServiceCollection services, IConfigurationRoot configurationRoot)
+        {
+            return services.Replace(ServiceDescriptor.Singleton<IConfigurationAccessor>(new DefaultConfigurationAccessor(configurationRoot)));
+        }
+
+        public static IConfigurationRoot GetConfiguration(this IServiceCollection services)
+        {
+            return services.GetSingletonInstance<IConfigurationAccessor>().Configuration;
+        }
+    }
+}

src/Volo.Abp.Core/Volo/Abp/Configuration/DefaultConfigurationAccessor.cs

@@ -0,0 +1,23 @@
+using Microsoft.Extensions.Configuration;
+
+namespace Volo.Abp.Configuration
+{
+    public class DefaultConfigurationAccessor : IConfigurationAccessor
+    {
+        public static DefaultConfigurationAccessor Empty { get; }
+
+        public virtual IConfigurationRoot Configuration { get; }
+
+        static DefaultConfigurationAccessor()
+        {
+            Empty = new DefaultConfigurationAccessor(
+                new ConfigurationBuilder().Build()
+            );
+        }
+
+        public DefaultConfigurationAccessor(IConfigurationRoot configuration)
+        {
+            Configuration = configuration;
+        }
+    }
+}

src/Volo.Abp.Core/Volo/Abp/Configuration/IConfigurationAccessor.cs

@@ -0,0 +1,9 @@
+using Microsoft.Extensions.Configuration;
+
+namespace Volo.Abp.Configuration
+{
+    public interface IConfigurationAccessor
+    {
+        IConfigurationRoot Configuration { get; }
+    }
+}

src/Volo.Abp.Core/Volo/Abp/Internal/InternalServiceCollectionExtensions.cs

@@ -1,5 +1,7 @@
-using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
+using Volo.Abp.Configuration;
 using Volo.Abp.Modularity;
 using Volo.Abp.Reflection;
 
@@ -20,6 +22,7 @@ namespace Volo.Abp.Internal
             var assemblyFinder = new AssemblyFinder(abpApplication);
             var typeFinder = new TypeFinder(assemblyFinder);
 
+            services.TryAddSingleton<IConfigurationAccessor>(DefaultConfigurationAccessor.Empty);
             services.TryAddSingleton<IModuleLoader>(moduleLoader);
             services.TryAddSingleton<IAssemblyFinder>(assemblyFinder);
             services.TryAddSingleton<ITypeFinder>(typeFinder);

test/Volo.Abp.Core.Tests/Volo/Abp/Configuration/ConfigurationAccessor_Tests.cs

@@ -0,0 +1,52 @@
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Shouldly;
+using Volo.Abp.Modularity;
+using Xunit;
+
+namespace Volo.Abp.Configuration
+{
+    public class ConfigurationAccessor_Tests
+    {
+        [Fact]
+        public void Should_Use_Empty_ConfigurationRoot_By_Default()
+        {
+            using (var application = AbpApplicationFactory.Create<IndependentEmptyModule>())
+            {
+                var configuration1 = application.Services.GetConfiguration();
+                configuration1.ShouldNotBeNull();
+
+                application.Initialize();
+
+                var configuration2 = ResolveConfiguration(application);
+
+                configuration2.ShouldBe(configuration1);
+            }
+        }
+
+        [Fact]
+        public void Should_Use_The_Registered_ConfigurationRoot()
+        {
+            using (var application = AbpApplicationFactory.Create<IndependentEmptyModule>())
+            {
+                var myConfiguration = new ConfigurationBuilder().Build();
+                application.Services.AddConfiguration(myConfiguration);
+                application.Services.GetConfiguration().ShouldBe(myConfiguration);
+
+                application.Initialize();
+
+                var configuration = ResolveConfiguration(application);
+
+                configuration.ShouldBe(myConfiguration);
+            }
+        }
+
+        private static IConfigurationRoot ResolveConfiguration(IAbpApplication application)
+        {
+            return application
+                .ServiceProvider
+                .GetRequiredService<IConfigurationAccessor>()
+                .Configuration;
+        }
+    }
+}