developerIdentity-example.cs

using Azure.Identity;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Configuration.AzureAppConfiguration;
using Microsoft.Extensions.Hosting;
using System;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.DependencyInjection;

namespace Example
{
    /// <summary>
    /// Main Program
    /// </summary>
    public class Program
    {
        private static string _appConfigEndpointPattern = "https://{0}-{1}-{2}.azconfig.io";

        /// <summary>
        /// Entry point
        /// </summary>
        /// <param name="args"></param>
        public static void Main(string[] args)
        {
            CreateHostBuilder(args)
                .Build()
                .Run();
        }

        /// <summary>
        /// Create IWebHostBuilder
        /// </summary>
        /// <param name="args"></param>
        /// <returns></returns>
        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.ConfigureAppConfiguration((hostingContext, config) =>
                        {
                            var settings = config.Build();
                            var environmentName = settings["EnvironmentNameOverride"] ?? hostingContext.HostingEnvironment.EnvironmentName;
                            var regionName = settings["Datacenter"];
                            var productName = settings["AppConfig:AppConfigName"];

                            var credentials = new DefaultAzureCredential(
                                new DefaultAzureCredentialOptions 
                                {
                                    /* broken on linux, currently unreliable to be honest */
                                    ExcludeSharedTokenCacheCredential = true, 

                                    // some devs have a Service Principal in ENV vars, don't want that, we want the developer to auth.
                                    ExcludeEnvironmentCredential = true, 

                                    /* By using azure CLI login, in combination with a volume mount of $HOME/.azure we can pass
                                     * our local machine tokens into the docker container that gets run to debug.
                                     */
                                    ExcludeAzureCliCredential = false, 

                                    // these work for local development when NOT in docker, so leaving them enabled, but they don't work in docker.
                                    ExcludeInteractiveBrowserCredential = false,
                                    ExcludeVisualStudioCredential = false,
                                    ExcludeVisualStudioCodeCredential = false,
                                    
                                    // managed identity will work fine if available (system OR user assigned)
                                    ExcludeManagedIdentityCredential = false,

                                    // set this to use User Assigned Managed Identity
                                    //ManagedIdentityClientId = ""
                                });
                            var appConfigUriString = string.Format(_appConfigEndpointPattern, environmentName, regionName, productName);

                            config.AddAzureAppConfiguration(options =>
                            {
                                options.Connect(new Uri(appConfigUriString, UriKind.Absolute), credentials)
                                    .ConfigureKeyVault(kv =>
                                    {
                                        kv.SetCredential(credentials);
                                    })
                                    // Load all configuration values with no label
                                    .Select(KeyFilter.Any, LabelFilter.Null)
                                    // Add/Override with any configuration values specific to current environment
                                    .Select(KeyFilter.Any, environmentName.ToLower());
                            });

                            var thing = hostingContext;
                        });
                    webBuilder.UseStartup<Startup>();
                });
    }
}

Dockerfile

#See https://aka.ms/containerfastmode to understand how Visual Studio uses this Dockerfile to build your images for faster debugging.

FROM mcr.microsoft.com/dotnet/core/aspnet:3.1 AS base
#AZ CLI installed at the base layer so that Developer login works in debug mode
RUN curl -sL https://aka.ms/InstallAzureCLIDeb | bash
WORKDIR /app
EXPOSE 80

FROM mcr.microsoft.com/dotnet/core/sdk:3.1 AS build
WORKDIR /src
COPY ["Host/Host.csproj", "Host/"]
RUN dotnet restore "Host/Host.csproj"
COPY . .
WORKDIR "/src/Host"
RUN dotnet build --no-restore "Host.csproj" -c Release -o /app/build

FROM build AS publish
RUN dotnet publish "Host.csproj" -c Release -o /app/publish

FROM base AS final
WORKDIR /app
COPY --from=publish /app/publish .
ENTRYPOINT ["dotnet", "Host.dll"]

Host.csproj

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.1</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
    <AssemblyName>Host</AssemblyName>
    <RootNamespace>Host</RootNamespace>
    <DockerDefaultTargetOS>Linux</DockerDefaultTargetOS>

    <!-- 
      By using azure CLI login, in combination with a volume mount of $HOME/.azure (/root) we can pass
      our local machine tokens into the docker container that gets run to debug.
    -->
    <DockerfileRunArguments>--mount type=bind,source="$(USERPROFILE)\.azure",target=/root/.azure</DockerfileRunArguments>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="AspNetCore.HealthChecks.SqlServer" Version="3.1.1" />
    <PackageReference Include="Azure.Identity" Version="1.3.0" />
    <PackageReference Include="Microsoft.ApplicationInsights" Version="2.11.0" />
    <PackageReference Include="Microsoft.ApplicationInsights.AspNetCore" Version="2.8.2" />
    <PackageReference Include="Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore" Version="2.2.1" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.Versioning" Version="4.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.OData" Version="7.5.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="2.2.6" />
    <PackageReference Include="Microsoft.Extensions.Configuration.AzureAppConfiguration" Version="4.1.0" />
    <PackageReference Include="Microsoft.VisualStudio.Azure.Containers.Tools.Targets" Version="1.10.10" />
    <PackageReference Include="NSwag.AspNetCore" Version="13.1.3" />
    <PackageReference Include="Polly" Version="7.2.1" />

  </ItemGroup>

</Project>