具有 Entity Framework "DefaultConnection" 应用程序设置的 Azure Key Vault

Question

我正在尝试使用 Azure Key Vault 为 Entity Framework 存储我的网络 api 连接字符串。理想情况下，我想避免将密钥保管库 nuget 包与我的数据访问代码耦合。我的 dbContext class 有两个构造函数：

public MyDbContext() : base("DefaultConnection")
{ . . . }

public MyDbContext(string connectionString) : base(connectionString)
{ . . . }

我的代码使用无参数构造函数，它从 Web 配置中获取连接字符串。有些地方我实例化了一个新的MyDbContext对象，禁止使用注入的解决方案。

我采用的方法是在我的 dbcontext 上使用连接字符串定位器设置静态属性：

public interface IConnectionStringLocator
{ string Get(); }

public class DefaultConnectionStringLocator : IConnectionStringLocator
{
    public string Get()
    {
        return "DefaultConnection";
    }
}

public static IConnectionStringLocator ConnectionStringLocator { get; set; } =
    new DefaultConnectionStringLocator();

我的网络 api 项目有用于检索密钥保管库机密的 nuget 包。所以在我的 Global.asax 文件中我有这个：

protected void Application_Start()
{
    MyDbContext.ConnectionStringLocator = new ConnectionStringLocator("DefaultConnection");
}

public class ConnectionStringLocator : IConnectionStringLocator
{
    private  readonly string _connectionStringName;

    public ConnectionStringLocator(string connectionStringName)
    {
        this._connectionStringName = connectionStringName;
    }
    public string Get()
    {
        var keyVaultName = WebConfigurationManager.AppSettings.Get("KeyVaultName");
        if (keyVaultName == "develop")
            return _connectionStringName;
        else
        {
            AzureServiceTokenProvider azureServiceTokenProvider = new AzureServiceTokenProvider();
            var keyVaultClient =
                new KeyVaultClient(
                    new KeyVaultClient.AuthenticationCallback(azureServiceTokenProvider.KeyVaultTokenCallback));
            var defaultConnectionSecret =
                keyVaultClient.GetSecretAsync($"https://{keyVaultName}.vault.azure.net/secrets/{this._connectionStringName}");

            return defaultConnectionSecret.Result.Value;
        }
    }
}

我发布了这个并且它有效，但是 "feel" 不对。

另一种选择是遵循这篇文章 https://blog.falafel.com/keeping-secrets-with-azure-key-vault/，但这需要我将 KeyVault API 包与我的数据访问结合起来。

我正在寻找反馈和方向。我应该补充一点，我想使用密钥保管库的原因是因为它允许我拥有 azure 管理员，他们可以在线查看应用程序设置，而无需通过连接字符串访问 sql 数据库。

具有新 MSI 实现的 KeyVault 资源：https://github.com/Azure-Samples/app-service-msi-keyvault-dotnet/

Answer 1

这是我解决这个问题的方法，以防其他人无意中发现它。

创建了一个 ConfigurationManager class，它首先尝试从 Key Vault 获取值，但失败时它使用 WebConfigurationManager 读取应用程序设置。

    public static class ConfigurationManager
{
    public static string KeyVaultName => WebConfigurationManager.AppSettings.Get("KeyVaultName");
    private static readonly Dictionary<string, string> ConfigurationCache = new Dictionary<string, string>();
    private static SecretBundle GetSecret(string secretName, string vaultName = null)
    {
        AzureServiceTokenProvider azureServiceTokenProvider = new AzureServiceTokenProvider();
        var keyVaultClient =
            new KeyVaultClient(
                new KeyVaultClient.AuthenticationCallback(azureServiceTokenProvider.KeyVaultTokenCallback));
        var secretUri = $"https://{vaultName ?? KeyVaultName}.vault.azure.net/secrets/{secretName}";
        var secret = keyVaultClient.GetSecretAsync(secretUri);
        return secret.Result;
    }

    public static string GetAppSettingValue(string secretName, string vaultName = null)
    {
        vaultName = vaultName ?? KeyVaultName;
        string key = $"{vaultName}:{secretName}";
        string value;

        if (ConfigurationCache.TryGetValue(key, out value))
            return value;

        if (string.IsNullOrEmpty(vaultName) || vaultName == "develop")
        {
            value = WebConfigurationManager.AppSettings.Get(secretName);
            ConfigurationCache.Add(key, value);
            return value;
        }

        var secret = GetSecret(secretName);
        value = secret.Value;
        ConfigurationCache.Add(key, value);
        return value;
    }

    public static void SetAppSettingValue(string secretName, string value, string vaultName = null)
    {
        vaultName = vaultName ?? KeyVaultName;
        string key = $"{vaultName}:{secretName}";

        if (ConfigurationCache.ContainsKey(key))
            ConfigurationCache[key] = value;
        else
        {
            WebConfigurationManager.AppSettings[key] = value;
            ConfigurationCache.Add(key, value);
        }


    }
    public static string GetConnectionStringValue(string secretName, string vaultName = null)
    {
        vaultName = vaultName ?? KeyVaultName;
        string key = $"{vaultName}:{secretName}";
        string value;

        if (ConfigurationCache.TryGetValue(key, out value))
            return value;

        if (string.IsNullOrEmpty(vaultName) || vaultName == "develop")
        {
            value = WebConfigurationManager.ConnectionStrings[secretName].ConnectionString;
            ConfigurationCache.Add(key, value);
            return value;
        }

        var secret = GetSecret(secretName);
        value = secret.Value;
        ConfigurationCache.Add(key, value);
        return value;
    }
}

然后在我的 dbcontext class 中调用 Configurationmanager.GetConnectionStringValue("DefaultConnection").

    public MyDbContext()
        : base(ConfigurationManager.GetConnectionStringValue("DefaultConnection"))
    {...}

Answer 2

对于 .NET 4.7.1 或更高版本，您可以使用 Configuration Builders for .NET to connect to key vault with just a small amount of XML in appsettings or web.config files. I have used the library along with XML transformations and azure devops to connect to different key vaults based on the environment. I talked about it in my blog post。

具有 Entity Framework "DefaultConnection" 应用程序设置的 Azure Key Vault

Azure Key Vault with Entity Framework "DefaultConnection" app setting

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