Connecting and Databse Migration for Entity Framework Core using Key Vault and Package Manager Console

Question

I changed my appSettings.config to no longer have connection strings as they are now all in Azure Key Vault. I was able to connect no problem, but now when I try to create the db using EF code first migrations in a new azure db using

add-migration InitialCreate

Value cannot be null.
Parameter name: connectionString

I am getting the error:

        public Startup(IHostingEnvironment env)
    {
        AutomapperConfiguration.Configure();
        _hostingEnvironment = env;
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", false, true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", true)
            .AddEnvironmentVariables();

        if (env.EnvironmentName == Constant.EnvironmentName_QA || env.EnvironmentName == Constant.EnvironmentName_Staging || env.EnvironmentName == Constant.EnvironmentName_Production)
            env.ConfigureNLog($"nlog.{env.EnvironmentName}.config");
        else
            env.ConfigureNLog($"nlog.config");


        builder.AddAzureKeyVault(Configuration["AzureVault:Vault"], Configuration["AzureVault:ClientId"], Configuration["AzureVault:ClientSecret"]);

        Configuration = builder.Build();

      }




Configuration(){
.
.
.
services.AddDbContext<SafeContext>(options => options.UseSqlServer(Configuration[Configuration["AzureVaultKeys:DBConnectionString"]]));
.
.
.
}

Answer 1

According to my test, we can use the following steps to implement migrations

1. Install SDk

<PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="3.1.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.2" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.1.2">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>
<PackageReference Include="Microsoft.Extensions.Configuration.AzureKeyVault" Version="3.1.2" />

2. Code

   a. Program.cs

    public static void Main(string[] args)
      {
   
          var host = CreateHostBuilder(args).Build();
   
          using (var scope = host.Services.CreateScope())
          {
              var services = scope.ServiceProvider;
              try
              {
                  var context = services.GetRequiredService<SchoolContext>();
                  DbInitializer.Initialize(context);
              }
              catch (Exception ex)
              {
                  var logger = services.GetRequiredService<ILogger<Program>>();
                  logger.LogError(ex, "An error occurred while seeding the database.");
              }
          }
   
          host.Run();
      }
   
      public static IHostBuilder CreateHostBuilder(string[] args) =>
          Host.CreateDefaultBuilder(args)
      .ConfigureAppConfiguration((context, config) =>
      {
   
          config.SetBasePath(context.HostingEnvironment.ContentRootPath)
                 .AddJsonFile("appsettings.json", false, true)
                 .AddJsonFile($"appsettings.{context.HostingEnvironment.EnvironmentName}.json", true)
                 .AddEnvironmentVariables();
          var builtConfig = config.Build();
          config.AddAzureKeyVault(
                      $"https://{builtConfig["KeyVault:Vault"]}.vault.azure.net/",
                      builtConfig["KeyVault:ClientId"],
                      builtConfig["KeyVault:ClientSecret"],
                      new DefaultKeyVaultSecretManager());
   
   
      })
      .ConfigureWebHostDefaults(webBuilder =>
      {
          webBuilder.UseStartup<Startup>();
      });
   

   b. Startup.cs

   public void ConfigureServices(IServiceCollection services)
       {
           services.AddDbContext<SchoolContext>(options =>
       options.UseSqlServer(Configuration["<your secret name>"])); //For example you secret name is ConnectionStrings--DefaultConnection, the code is  Configuration["ConnectionStrings:DefaultConnection"]  
           services.AddControllersWithViews();
       }
   

3 migrate

add-migration InitialCreate

For more details, please refer to

https://learn.microsoft.com/en-us/aspnet/core/security/key-vault-configuration?view=aspnetcore-3.1

https://learn.microsoft.com/en-us/aspnet/core/data/ef-mvc/intro?view=aspnetcore-3.1