带有实体框架“DefaultConnection”应用程序设置的Azure密钥存储库

Question

我试图使用Azure Key Vault来存储实体框架的web api连接字符串。理想情况下，我希望避免将key vault nuget包与我的数据访问代码耦合。我的dbContext类有两个构造函数：

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

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

我的代码使用了从web配置中获取连接字符串的无参数构造函数。我在某些地方实例化了一个新的MyDbContext对象，这禁止了使用注入的解决方案。

我采用的路线是在我的dbcontext上设置一个带有连接字符串定位器的静态属性：

public interface IConnectionStringLocator
{ string Get(); }

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

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

我的web api项目有用于检索密钥库机密的nuget包。因此，在我的global.asax文件中，我有以下内容：

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;
        }
    }
}

我发表了这篇文章，它很有效，但它“感觉”不对。

另一个选择是遵循本文https://blog.falafel.com/keeping-secrets-with-azure-key-vault/但这需要我将KeyVault API包与我的数据访问连接起来。

我在寻找反馈和方向。我应该补充的是，我想使用key vault的原因是，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

以下是我如何解决这个问题的，以防其他人绊倒。

创建了一个ConfigurationManager类，该类首先尝试从密钥库中获取值，但失败后使用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类中，我调用ConfigurationManager.GetConnectionStringValue（“DefaultConnection”）。

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