IdentityServer4 负载均衡配置

　　在不用到负载之前，一切都很好，但是部署多个实例之后，问题挺多的：session问题、令牌签发后的校验问题。

在此之前，先自查官方文档：Deployment — IdentityServer4 1.0.0 documentation

把必要的东西都配置正确，然后继续排查。

session问题

　　 在需要经常需要与统一身份认证平台进行交互的情况（比如，A站点和B站点都是统一身份认证平台下的子系统，希望A站点登录后，在B进行登录的时候可以免登录的情形），建议不用继续使用sessionID，如果不需要，则存放在redis，实现分布式session也是选择。

令牌签发后的校验问题

　　部署后启动：

2021-11-01 12:01:50.098 [WRN] Using an in-memory repository. Keys will not be persisted to storage

然后在A站点登录之后，关闭A站点，启动B站点进行测试是否正常可以验证通过，会发现提示去登录，查看日志发现：

2021-11-01 12:01:50.276 [ERR] cookie Showing login: User is not authenticated

然后F12查看cookie已经被删除，讲白了就是AB两个站点并不互认，官方文档里面写着

IdentityServer itself is stateless and does not require server affinity - but there is data that needs to be shared between the instances.

我真想抽它鸭子的。

解决：

　　因为ids4是有引用到微软库的一个 Microsoft.AspNetCore.DataProtection （数据保护参考：ASP.NET Core数据保护 | Microsoft Docs）所以可以不用引用，你需要引用一个包：

Microsoft.AspNetCore.DataProtection.StackExchangeRedis

然后在使用：

var redis = ConnectionMultiplexer.Connect( Configuration["Redis:HostPort"]);
services.AddDataProtection()
        .SetApplicationName(Configuration["Redis:ApplicationName"])
        .PersistKeysToStackExchangeRedis( redis, "DataProtection-Keys");

就ok了，或者不想用StackExchangeRedis，就自己实现：

 public class CustomRedisXmlRepository : Microsoft.AspNetCore.DataProtection.Repositories.IXmlRepository
    {
        protected readonly IRedisCache redisCache;
        protected readonly int DBIndex;
        private readonly string key;

        public CustomRedisXmlRepository(IRedisCache redisCache, int dbIndex, string key)
        {
            this.redisCache = redisCache;
            this.DBIndex = dbIndex;
            this.key = key;
        }

        /// <inheritdoc />
        public IReadOnlyCollection<XElement> GetAllElements()
        {
            return GetAllElementsCore().ToList().AsReadOnly();
        }

        private IEnumerable<XElement> GetAllElementsCore()
        {
            foreach (var value in redisCache.GetList<string>(DBIndex,key))
            {
                yield return XElement.Parse(value);
            }
        }

        public void StoreElement(XElement element, string friendlyName)
        { 
            redisCache.AddList(DBIndex,key, element.ToString(SaveOptions.DisableFormatting));
        }
    }

扩展：

public static class RedisDataProtectionBuilderExtensions
    {
        private const string DataProtectionKeysName = "DataProtection-Keys";
        private const int DefaultDBIndex = 0;

        public static IDataProtectionBuilder PersistKeysToRedis(this IDataProtectionBuilder builder, IRedisCache redisCache,int dbIndex, string key)
        {
            if (builder == null)
            {
                throw new ArgumentNullException(nameof(builder));
            }
            if (redisCache == null)
            {
                throw new ArgumentNullException(nameof(IRedisCache));
            }
            return PersistKeysToRedisInternal(builder, redisCache, dbIndex, key);
        }

        public static IDataProtectionBuilder PersistKeysToRedis(this IDataProtectionBuilder builder, IRedisCache redisCache)
        {
            return PersistKeysToRedis(builder, redisCache, DefaultDBIndex, DataProtectionKeysName);
        }

        private static IDataProtectionBuilder PersistKeysToRedisInternal(IDataProtectionBuilder builder, IRedisCache redisCache, int dbIndex, string key)
        {
            builder.Services.Configure<KeyManagementOptions>(options =>
            {
                options.XmlRepository = new CustomRedisXmlRepository(redisCache, dbIndex, key);
            });
            return builder;
        }
    }

引用

 var redis = services.BuildServiceProvider().GetService<IRedisCache>(); 
 services.AddDataProtection()
         .SetApplicationName(config.RedisOptions.KeyPrefix+ "-Identityserver4-Production-Key")
         .PersistKeysToRedis(redis, Application.Configs.RedisKey.Application, config.RedisOptions.KeyPrefix + "-DataProtection-Keys");

然后重新测试，会发现token已经校验通过：

2021-11-01 12:02:04.515 [INF] Token request validation success, {"ClientId":"zhicheng","ClientName":"**","GrantType":"authorization_code","Scopes":null,"AuthorizationCode":"****93B3","RefreshToken":"********","UserName":null,"AuthenticationContextReferenceClasses":null,"Tenant":null,"IdP":null,"Raw":{"client_id":"***","client_secret":"***REDACTED***","grant_type":"authorization_code","code":"153AF90A4B84AC5C0C8ABA1E22483A05936B6009E123AA8937015F26FD6A93B3","redirect_uri":"http://localhost:6001/Home/Index"},"$type":"TokenRequestValidationLog"}  

坐等下班！