Azure Durable Function如何替换local.settings.json的AzureWebJobsStorage为Key Vault值

实现方案 #

你不需要修改local.settings.json的物理文件内容，只需要在Startup.cs中通过内存配置源覆盖AzureWebJobsStorage的配置值，再替换默认的配置注入即可，完整修改后的Startup代码如下：

public class Startup : FunctionsStartup
{
    private const string localSettingsJson = "local.settings.json";

    private IConfigurationBuilder GetConfiguration(FunctionsHostBuilderContext context) => new ConfigurationBuilder()
            .SetBasePath(context.ApplicationRootPath)
            .AddJsonFile(localSettingsJson, optional: true, reloadOnChange: true)
            .AddEnvironmentVariables();

    public override void Configure(IFunctionsHostBuilder builder)
    {
        FunctionsHostBuilderContext context = builder.GetContext();
        var configBuilder = GetConfiguration(context);

        DefaultAzureCredential credential = new DefaultAzureCredential(new DefaultAzureCredentialOptions { ManagedIdentityClientId = "61063c32-379d-4e9d-8977-4b826c2bc50a" });
        SecretClient secretClient = new SecretClient(new Uri("https://storageaccount.vault.azure.net/"), credential);
        configBuilder.AddAzureKeyVault(secretClient, new KeyVaultSecretManager());

        IConfigurationRoot config = configBuilder.Build();
        var keyVaultConnectionStringValue = config["storageaccount-connectionstring"];

        // 新增代码开始
        // 构造内存配置源，覆盖AzureWebJobsStorage配置值
        var overrideConfig = new Dictionary<string, string>
        {
            // 兼容两种配置键格式，适配不同版本Functions运行时的读取逻辑
            ["AzureWebJobsStorage"] = keyVaultConnectionStringValue,
            ["Values:AzureWebJobsStorage"] = keyVaultConnectionStringValue
        };
        // 合并原有配置和覆盖配置
        config = new ConfigurationBuilder()
            .AddConfiguration(config)
            .AddInMemoryCollection(overrideConfig)
            .Build();
        // 替换默认IConfiguration注入，让Functions运行时使用自定义配置
        builder.Services.AddSingleton<IConfiguration>(config);
        // 新增代码结束

        var services = builder.Services;
        services.ConfigureAutoMapper();
    }
}

原理说明 #

• Azure Functions运行时读取AzureWebJobsStorage等配置项时，会优先读取DI容器中注入的IConfiguration实例
• 用内存配置源添加的配置优先级高于local.settings.json等文件配置源，不需要修改物理文件也不需要依赖环境变量就能实现配置覆盖
• 本地开发时如果需要保留存储模拟器的配置，可加环境判断，仅在云端运行时执行配置覆盖逻辑即可

内容的提问来源于stack exchange，提问作者user2043071