Use correct interfaces to build host (#17)

* Do not overwrite existing IConfiguration
* Adding documentation and syntax changes

**Possible breaking changes:** 
1. Please read sample `Startup.cs` to see how to use `UseAppSettings`.
2. This package will now use AZURE_FUNCTIONS_ENVIRONMENT to determine your environment. It is `Production` by default on Azure servers, `Development` locally. 

Co-authored-by: Wayne Brantley <wayne@miniter.com>

Author: junalmeida

Autofac.Extensions.DependencyInjection.AzureFunctions/AppSettingsExtensions.cs

@@ -1,10 +1,8 @@
 using Microsoft.Azure.Functions.Extensions.DependencyInjection;
 using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.DependencyInjection;
-using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Hosting;
 using System;
 using System.IO;
-using System.Reflection;
 
 namespace Autofac.Extensions.DependencyInjection.AzureFunctions
 {
@@ -14,57 +12,53 @@ namespace Autofac.Extensions.DependencyInjection.AzureFunctions
     public static class AppSettingsExtensions
     {
         /// <summary>
-        /// Creates an <see cref="IConfiguration"/> instance and attaches to an `appsettings.json` file, also adding an `appsettings.{environment}.json` on top of it, if available, based on current ASPNETCORE_ENVIRONMENT environment variable.
+        /// Creates an <see cref="IConfiguration"/> instance and attaches to an `appsettings.json` file, also adding an `appsettings.{environment}.json` on top of it, if available, based on current AZURE_FUNCTIONS_ENVIRONMENT environment variable.
         /// </summary>
-        /// <param name="hostBuilder">An instance of <see cref="IFunctionsHostBuilder"/>.</param>
-        /// <returns>The IFunctionsHostBuilder.</returns>
-        public static IFunctionsHostBuilder UseAppSettings(this IFunctionsHostBuilder hostBuilder)
+        /// <param name="builder">An instance of <see cref="IFunctionsConfigurationBuilder"/>.</param>
+        /// <param name="reloadOnChange">Whether the configuration should be reloaded on file change.</param>
+        /// <returns>The <see cref="IFunctionsConfigurationBuilder"/>.</returns>
+        public static IFunctionsConfigurationBuilder UseAppSettings(this IFunctionsConfigurationBuilder builder, bool reloadOnChange = false)
         {
-            var fileInfo = new FileInfo(Assembly.GetExecutingAssembly().Location);
-            string currentDirectory = fileInfo.Directory.Parent.FullName;
+            var context = builder.GetContext();
+            builder.ConfigurationBuilder
+                .AddJsonFile(Path.Combine(context.ApplicationRootPath, "appsettings.json"), optional: true, reloadOnChange: reloadOnChange)
+                .AddJsonFile(Path.Combine(context.ApplicationRootPath, $"appsettings.{builder.GetCurrentEnvironmentName()}.json"), optional: true, reloadOnChange: reloadOnChange)
+                .AddEnvironmentVariables();
 
-            var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
-            if (string.IsNullOrWhiteSpace(environment))
-                environment = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
-            if (string.IsNullOrWhiteSpace(environment))
-                environment = "Development"; // Fallback to Development when none is set.
-
-            return UseAppSettings(hostBuilder, (builder) =>
-            {
-                builder
-                    .SetBasePath(currentDirectory)
-                    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
-                    .AddJsonFile($"appsettings.{environment}.json", optional: true, reloadOnChange: true)
-                    .AddJsonFile("host.json", optional: true, reloadOnChange: true)
-                    .AddEnvironmentVariables();
-            });
+            return builder;
         }
 
         /// <summary>
-        /// Creates an <see cref="IConfiguration"/> instance and configures it as declared by <paramref name="configurationAction"/> action.
+        /// Calculate environment from unreliable function environment setting. 
+        /// github.com/Azure/azure-functions-host/issues/6239 problem determining environment.
         /// </summary>
-        /// <param name="hostBuilder">An instance of <see cref="IFunctionsHostBuilder"/>.</param>
-        /// <param name="configurationAction">Action on a <see cref="IConfigurationBuilder"/> that adds configurations to a .NET Core application.</param>
-        /// <returns>The IFunctionsHostBuilder.</returns>
-        public static IFunctionsHostBuilder UseAppSettings(this IFunctionsHostBuilder hostBuilder, Action<IConfigurationBuilder> configurationAction = null)
+        /// <param name="builder"></param>
+        /// <returns></returns>
+        public static string GetCurrentEnvironmentName(this IFunctionsHostBuilder builder)
         {
-            var configurationBuilder = new ConfigurationBuilder() as IConfigurationBuilder;
-
-            using (var temporaryServiceProvider = hostBuilder.Services.BuildServiceProvider())
-            {
-                var configRoot = temporaryServiceProvider.GetService<IConfiguration>();
-                if (configRoot != null)
-                {
-                    configurationBuilder.AddConfiguration(configRoot);
-                }
-            }
+            return GetCurrentEnvironmentName(builder.GetContext().EnvironmentName);
+        }
 
-            configurationAction?.Invoke(configurationBuilder);
-            var configuration = configurationBuilder.Build();
+        /// <summary>
+        /// Calculate environment from unreliable function environment setting.
+        /// github.com/Azure/azure-functions-host/issues/6239 problem determining environment.
+        /// </summary>
+        /// <param name="builder"></param>
+        /// <returns></returns>
+        public static string GetCurrentEnvironmentName(this IFunctionsConfigurationBuilder builder)
+        {
+            return GetCurrentEnvironmentName(builder.GetContext().EnvironmentName);
+        }
 
-            hostBuilder.Services.Replace(ServiceDescriptor.Singleton(typeof(IConfiguration), configuration));
+        private static string GetCurrentEnvironmentName(string contextEnvironmentName)
+        {
 
-            return hostBuilder;
+            string environmentName = Environment.GetEnvironmentVariable("AZURE_FUNCTIONS_ENVIRONMENT") ??
+                                     Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ??
+                                     Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT") ??
+                                     contextEnvironmentName ??
+                                     EnvironmentName.Development;
+            return environmentName;
         }
     }
 }

Autofac.Extensions.DependencyInjection.AzureFunctions/LoggerExtensions.cs

@@ -3,7 +3,6 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using System;
-using System.Linq;
 
 namespace Autofac.Extensions.DependencyInjection.AzureFunctions
 {
@@ -20,10 +19,9 @@ public static class LoggerExtensions
         /// <returns>The IFunctionsHostBuilder.</returns>
         public static IFunctionsHostBuilder UseLogger(this IFunctionsHostBuilder hostBuilder, Action<ILoggingBuilder, IConfiguration> configure)
         {
-            var configuration = hostBuilder.Services.Where(x => x.ServiceType == typeof(IConfiguration)).SingleOrDefault()?.ImplementationInstance as IConfiguration;
+            var configuration = hostBuilder.GetContext().Configuration;
 
             hostBuilder.Services.AddLogging((config) => configure?.Invoke(config, configuration));
-
             return hostBuilder;
         }
     }

Autofac.Extensions.DependencyInjection.AzureFunctions/LoggerModule.cs

@@ -6,7 +6,6 @@ internal class LoggerModule : Module
     {
         public const string functionNameParam = "functionName";
         public const string loggerFactoryParam = "loggerFactory";
-        public const string telemetryParam = "telemetry";
 
         protected override void Load(ContainerBuilder builder)
         {

README.md

@@ -34,27 +34,43 @@ public class Startup : FunctionsStartup
     public override void Configure(IFunctionsHostBuilder builder)
     {
         builder
-            .UseAppSettings() // this is optional, this will bind IConfiguration in the container.
+            // This is the required call in order to use autofac in your azure functions app
             .UseAutofacServiceProviderFactory(ConfigureContainer);
     }
 
+    public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder builder)
+    {
+        // this is optional and will bind IConfiguration with appsettings.json in
+        // the container, like it is usually done in regular dotnet console and
+        // web applications.
+        builder.UseAppSettings();
+    }
+
     private void ConfigureContainer(ContainerBuilder builder)
     {
         builder
             .Register(activator =>
             {
                 // Example on how to bind settings from appsettings.json
                 // to a class instance
-                var mySettings = new MySettings();
+                var section = activator.Resolve<IConfiguration>().GetSection(nameof(MySettings));
 
-                var config = activator.Resolve<IConfiguration>();
-                config.GetSection(nameof(MySettings)).Bind(mySettings);
+                var instance = section.Get<MySettings>();
 
-                return mySettings;
+                // If you expect IConfiguration to change (with reloadOnChange=true), use
+                // token to rebind.
+                ChangeToken.OnChange(
+                    () => section.GetReloadToken(),
+                    (state) => section.Bind(state),
+                    instance);
+
+                return instance;
             })
             .AsSelf()
             .SingleInstance();
 
+
+
         // Register all functions that resides in a given namespace
         // The function class itself will be created using autofac
         builder

SampleAutofacFunction/SampleAutofacFunction.csproj

@@ -20,6 +20,10 @@
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
       <DependentUpon>appsettings.json</DependentUpon>
     </None>
+    <None Update="appsettings.Development.json">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+      <DependentUpon>appsettings.json</DependentUpon>
+    </None>
     <None Update="host.json">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>

SampleAutofacFunction/Startup.cs

@@ -3,6 +3,7 @@
 using Microsoft.Azure.Functions.Extensions.DependencyInjection;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Primitives;
 using SampleAutofacFunction.Settings;
 
 [assembly: FunctionsStartup(typeof(SampleAutofacFunction.Startup))]
@@ -14,45 +15,62 @@ class Startup : FunctionsStartup
         public override void Configure(IFunctionsHostBuilder builder)
         {
             builder
-                .UseAppSettings()
+                // You can call UseLogger to change how logging is done on your app by code. 
                 .UseLogger(ConfigureLogger)
+                // This is the required call in order to use autofac in your azure functions app
                 .UseAutofacServiceProviderFactory(ConfigureContainer);
         }
 
         private void ConfigureLogger(ILoggingBuilder builder, IConfiguration config)
         {
             builder.AddConfiguration(config.GetSection("Logging"));
-            builder.AddApplicationInsightsWebJobs();
+        }
+
+        public override void ConfigureAppConfiguration(IFunctionsConfigurationBuilder builder)
+        {
+            // this is optional and will bind IConfiguration with appsettings.json in
+            // the container, like it is usually done in regular dotnet console and
+            // web applications.
+            builder.UseAppSettings(true);
         }
 
         private void ConfigureContainer(ContainerBuilder builder)
         {
             builder
                 .Register(activator =>
                 {
-                    var mySettings = new MySettings();
+                    // Example on how to bind settings from appsettings.json
+                    // to a class instance
+                    var section = activator.Resolve<IConfiguration>().GetSection(nameof(MySettings));
+
+                    var instance = section.Get<MySettings>();
 
-                    var config = activator.Resolve<IConfiguration>();
-                    config.GetSection(nameof(MySettings)).Bind(mySettings);
+                    // If you expect IConfiguration to change (with reloadOnChange=true), use
+                    // token to rebind.
+                    ChangeToken.OnChange(
+                       () => section.GetReloadToken(),
+                       (state) => section.Bind(state),
+                       instance);
 
-                    return mySettings;
+                    return instance;
                 })
                 .AsSelf()
                 .SingleInstance();
 
+            // Register all functions that resides in a given namespace
+            // The function class itself will be created using autofac
             builder
                 .RegisterAssemblyTypes(typeof(Startup).Assembly)
                 .InNamespace("SampleAutofacFunction.Functions")
-                .AsSelf()
-                .InstancePerTriggerRequest();
+                .AsSelf() // Azure Functions core code resolves a function class by itself.
+                .InstancePerTriggerRequest(); // This will scope nested dependencies to each function execution
 
             builder
                 .RegisterAssemblyTypes(typeof(Startup).Assembly)
                 .InNamespace("SampleAutofacFunction.Services")
                 .AsImplementedInterfaces()
                 .InstancePerTriggerRequest();
 
-
         }
     }
 }

SampleAutofacFunction/appsettings.Development.json

@@ -0,0 +1,6 @@
+{
+    "MySettings": {
+        "Value1": "Value 1 from appsettings.Development.json",
+        "Value2": "Value 2 from appsettings.Development.json"
+    }
+}

SampleAutofacFunction/local.settings.json

@@ -2,7 +2,6 @@
     "IsEncrypted": false,
     "Values": {
         "AzureWebJobsStorage": "UseDevelopmentStorage=true",
-        "FUNCTIONS_WORKER_RUNTIME": "dotnet",
-        "ASPNETCORE_ENVIRONMENT": "Production",
+        "FUNCTIONS_WORKER_RUNTIME": "dotnet"
     }
 }