CAP项目集成带身份和证书验证的MongoDB

大家好，我是Edison。

最近，在在ASP.NET 6中使用CAP事件总线时，碰到了这样一个需求：微服务采用的是MongoDB，而且还是带身份验证和 SSL根证书验证的。由于目前网上能找到的资料，都是不带身份验证的MongoDB，现在网络信息安全越来越被重视，那么就需要自己研究一番了。

CAP.MongoDB组件

CAP是一个开源的事件总线项目，在.NET社区已经十分流行了，它提供了多种存储方式：MSSQL, MySQL, PgSQL，MongoDB等，这里我们主要关注MongoDB。快速安装CAP.MongoDB组件：

PM> Install-Package DotNetCore.CAP.MongoDB

快速集成CAP.MongoDB组件（StartUp.cs）：

public void ConfigureServices(IServiceCollection services)
{
    // ...

    services.AddCap(x =>
    {
        x.UseMongoDB(opt=>{
            //MongoDBOptions
        });
        // x.UseXXX ...
    });
}

目前CAP提供的Options如下：

也就是说，CAP的Option只提供了一个DatabaseConnection选项，让我们自己构造Mongo链接字符串供CAP使用。

那么，我们就需要准确地构造这个Mongo连接字符串了。

这里，我们以之前分享的一篇文章《在ASP.NET 6中使用工作单元操作MongoDB》为基础，不熟悉的朋友可以先看看这篇文章。

前提条件/准备工作

这里我们假设在appsettings中我们针对MongoDB的配置项如下格式：

"MongoDatabaseConfigs": {
    "Servers": "xxx01.server.net,xxx02.server.net,xxx03.server.net",
    "Port": 27017, // optional, default : 27017
    "ReplicaSetName": "myrs",
    "DatabaseName": "TEST_DB",
    "AuthDatabaseName": "admin", // optional, default: admin
    "ApplicationName": "Todo",
    "UserName": "test_dev_user",
    "Password": "test_dev_password",
    "UseTLS": true,  // optional, default : false
    "AllowInsecureTLS": true, // optional, default : true
    "SslCertificatePath": "/etc/pki/tls/certs/MyCustomCA.cer"
}

配置项中给出了UserName、Password 还有 SSL证书的路径，这些都是需要构造到连接字符串中的。当然，在Kubernetes中，都建议放到Secret中去。

核心工作：封装构造连接字符串的方法

这里我们封装一个生成MongoDB连接字符串的静态方法，用于读取appsettings中的配置项，并帮我们生成CAP可以用的MongoDB连接字符串：

public static class DbConnUtil
{
    // Const Settings for Mongo
    private const int DEFAULT_CONNECT_TIMEOUT_MS = 10000; // 10s
    private const int DEFAULT_SERVER_SELECTION_TIMEOUT_MS = 5000; // 5s
    private const string DEFAULT_AUTH_MECHANISM = "SCRAM-SHA-256"; // SCRAM-SHA-256
    private const string DEFAULT_READ_PREFERENCE = "primaryPreferred"; // Primary Preferred
    private const string DEFAULT_SSL_INVALID_HOSTNAME_ALLOWED = "true"; // Allow Invalid HostName for SSL

    /// <summary>
    /// 获取MongoDB数据库连接字符串
    /// 需要在配置文件中提前根据指定Key进行设置
    /// </summary>
    public static string GetMongoDbConnectionString(IConfiguration config)
    {
        var servers = config["MongoDatabaseConfigs:Servers"];
        var port = config["MongoDatabaseConfigs:Port"] ?? "27017";
        if (string.IsNullOrWhiteSpace(servers))
            throw new ArgumentNullException("Mongo Servers Configuration is Missing!");
        var mongoServers = servers.Split(',');

        // Basic Auth
        var userName = config["MongoDatabaseConfigs:UserName"];
        var password = config["MongoDatabaseConfigs:Password"];
        if (string.IsNullOrWhiteSpace(userName) || string.IsNullOrWhiteSpace(password))
            throw new ArgumentNullException("Mongo Account Configuration is Missing!");

        // Uri
        var replicaName = config["MongoDatabaseConfigs:ReplicaSetName"];
        var authDatabaseName = config["MongoDatabaseConfigs:AuthDatabaseName"] ?? "admin";
        var mongoUriBuilder = new StringBuilder();
        mongoUriBuilder.Append($"mongodb://{userName}:{password}@");
        for (int i = 0; i < mongoServers.Length; i++)
        {
            if (i < mongoServers.Length - 1)
            {
                mongoUriBuilder.Append($"{mongoServers[i]}:{port},");
            }
            else
            {
                mongoUriBuilder.Append($"{mongoServers[i]}:{port}/?");
            }
        }

        // Settings
        var applicationName = config["MongoDatabaseConfigs:ApplicationName"];
        mongoUriBuilder.Append($"replicaSet={replicaName}");
        mongoUriBuilder.Append($"&appName={applicationName}");
        mongoUriBuilder.Append($"&authSource={authDatabaseName}");
        mongoUriBuilder.Append($"&authMechanism={DEFAULT_AUTH_MECHANISM}");
        mongoUriBuilder.Append($"&connectTimeoutMS={DEFAULT_CONNECT_TIMEOUT_MS}"); 
        mongoUriBuilder.Append($"&serverSelectionTimeoutMS={DEFAULT_SERVER_SELECTION_TIMEOUT_MS}");
        mongoUriBuilder.Append($"&readPreference={DEFAULT_READ_PREFERENCE}");

        // TLS/SSL Auth
        var useTLS = Convert.ToBoolean(config["MongoDatabaseConfigs:UseTLS"] ?? "false");
        if (useTLS)
        {
            var allowInsecureTls = Convert.ToBoolean(config["MongoDatabaseConfigs:AllowInsecureTLS"] ?? "true");
            var sslCertificatePath = config["MongoDatabaseConfigs:SslCertificatePath"];
            
            mongoUriBuilder.Append($"&ssl={useTLS}");
            mongoUriBuilder.Append($"&net.ssl.CAFile={sslCertificatePath}");
            mongoUriBuilder.Append($"&net.ssl.allowInvalidCertificates={DEFAULT_SSL_INVALID_HOSTNAME_ALLOWED}");
        }

        return mongoUriBuilder.ToString();
    }
}

最终可以生成的连接字符串为：

mongodb://test_dev_user:test_dev_password@xxx01:27017.server.net,xxx02.server.net:27017,xxx03.server.net:27017/?replicaSet=myrs&appName=Todo&authSource=admin&authMechanism=SCRAM-SHA-256&connectTimeoutMS=10000&serverSelectionTimeoutMS=5000&readPreference=primaryPreferred&ssl=True&net.ssl.CAFile=/etc/pki/tls/certs/MyCustomCA.cer&net.ssl.allowInvalidCertificates=true

ASP.NET Core集成CAP

这里我们使用刚刚封装的方法来生成Mongo连接字符串，来快速集成CAP：

public static IServiceCollection AddApplicationEventBus(this IServiceCollection services, IConfiguration config)
{
    ......
    // CAP EventBus
    services.AddCap(option =>
    {
        // Transport
        option.UseKafka(option =>
        {
            option.Servers = config["EventBusConfigs:KafkaServers"]
                ?? throw new ArgumentException("EventBusConfigs:KafkaServers must be set!");
            option.ConnectionPoolSize = int.Parse(config["EventBusConfigs:CapConnectionPoolSize"]
                ?? ApplicationDefaultSettings.Default_ConnectionPool_Size);
            option.CustomHeaders = e => new List<KeyValuePair<string, string>>
                    {
                        new KeyValuePair<string, string>(Headers.MessageId, SnowflakeId.Default().NextId().ToString()),
                        new KeyValuePair<string, string>(Headers.MessageName, e.Topic)
                    };

            if (Convert.ToBoolean(config["EventBusConfigs:EnableAuthorization"] ?? "false"))
            {
                var userName = config["EventBusConfigs:SaslUserName"];
                var passWord = config["EventBusConfigs:SaslPassword"];

                if (string.IsNullOrWhiteSpace(userName) || string.IsNullOrWhiteSpace(passWord))
                    throw new ArgumentNullException("Kafka username or password can't be null!");

                option.MainConfig.Add(KafkaMainConfigKey.SECURITY_PROTOCOL, KafkaProtocol.SASL_SSL);
                option.MainConfig.Add(KafkaMainConfigKey.SASL_MECHANISM, KafkaAuthMechanism.PLAIN);
                option.MainConfig.Add(KafkaMainConfigKey.SASL_USERNAME, userName);
                option.MainConfig.Add(KafkaMainConfigKey.SASL_PASSWORD, passWord);

                if (!string.IsNullOrWhiteSpace(config["EventBusConfigs:SslCertificatePath"]))
                    option.MainConfig.Add(KafkaMainConfigKey.SSL_CA_LOCATION, config["EventBusConfigs:SslCertificatePath"]);
                if (!string.IsNullOrWhiteSpace(config["EventBusConfigs:EnableSslCertificateVerification"]))
                    option.MainConfig.Add(KafkaMainConfigKey.ENABLE_SSL_CERT_VERIFICATION, config["EventBusConfigs:EnableSslCertificateVerification"]);
            }
        });
        option.SucceedMessageExpiredAfter = 3600 * 24 * int.Parse(config["EventBusConfigs:CapSuccessMsgExpireDays"];
        // Storage
        option.UseMongoDB(option =>
        {
            option.DatabaseConnection = DbConnUtil.GetMongoDbConnectionString(config);
            option.DatabaseName = config["MongoDatabaseConfigs:DatabaseName"] 
                ?? throw new ArgumentException("MongoDatabaseConfigs:DatabaseName must be set!");
            option.PublishedCollection = "msg.published";
            option.ReceivedCollection = "msg.received";
        });
    });

    ......

    return services;
}