背景

PowerShell DSC Pull Server因为证书过期挂了一个月，重新好了，会收到所有已经注册的server（称之为Node，或者Agent）这段时间积累的请求。为啥？问就是By design。

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ref: https://github.com/PowerShell/PowerShell/issues/2978

Nginx

然后Nginx 502错误

1. upstream timed out
   加大nginx读取updtream的时间
   proxy_read_timeout 3600;

2. no live upstreams while connecting to upstream
   这个本质问题是#1引发的

3. worker_connections are not enough while connecting to upstream
   加大worker_connections
   events {
   worker_connections 20000;
   }

4. WSARecv() failed (10054: An existing connection was forcibly closed by the remote host) while reading response header from upstream
   加大keepalive_requests和对应的keepalive_timeout

keepalive_requests 500;
keepalive_timeout 120s;

格式 和 作用，见：https://nginx.org/en/docs/ （别找错模块了）
逐个修复后，请求还是不断，查看Access log

Nginx Access log

可以看到2个请求每10分钟重试一直发，说明Report是失败了。

模拟Send Report

DSC web services没有开源，不清楚如何访问，只知道HTTP差不多可以访问

这个老哥说想要API

ref:https://github.com/dsccommunity/xPSDesiredStateConfiguration/issues/443

那就看看吧。

Specifies the Desired State Configuration Pull Model Protocol, which is used to get a client's configuration and modules from the server and to report the client's status back to the server. The protocol depends on HTTP for the transfer of all protocol messages.
ref: https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dscpm/ea744c01-51a2-4000-9ef2-312711dcc8c9?redirectedfrom=MSDN

看到没，这是基于HTTP发明个了协议啊, Desired State Configuration Pull Model Protocol。

很快，我们就找到了SendReport的介绍：https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dscpm/9484a812-d90e-42a8-b4f4-392f2ae1076c
文档写的很好，Demo很到位呀，来，copy...

等等，是不是编码乱了，这特么是啥乱七八糟的...

明察秋毫，下载文档协议文档读读...

打开文档

这个有用的信息，说的描述用的是ABNF语法，看这里：https://tools.ietf.org/search/rfc4234

可以可以，很规范。

高超的英语水平发挥了巨大的作用，终于可以读懂了：

//等号理解为组成
 DSC-SendReport-Request  =  DSC-SendReport-Req-Line DSC-SendReportSetReq-Headers DSC-SendReportReq-Body

//SP 就是空格的意思  
 DSC-SendReport-Req-Line   = "POST" SP Request-URI SP HTTP-Version CRLF
 Request-URI = Request-URI-Start DSC-SendReportRequest-URI-End
            
 DSC-SendReportRequest-URI-End = "Node(AgentId=" SQUOTE AgentID SQUOTE RBRACKET FSLASH "SendReport"

//分号就是注释的意思
 SQUOTE = %x27  ;  ' (Single Quote)
 RBRACKET = %x29 ; ) (Closing Bracket)
 FSLASH = %x2F ; / (Forward Slash)
 AgentID = UUID ; as specified in [RFC4122] 

//星号就是一个或多个的意思
//斜杠就是或者的意思            
 DSC-SendReportSetReq-Headers = *( DSC-SendReportSetReq-Header-REQ
      / DSC-SendReportSetReq-Header-OPT ) 
            
 DSC-SendReportSetReq-Header-REQ    = Host    ; section 14.23 of [RFC2616] 
           / Accept ; section 14.1 of [RFC2616] 
           / ContentType ; section 2.2.2.1.2
           / Content-Length ; section 14.13 of [RFC2616] 
            
 DSC-SendReportSetReq-Header-OPT    = Connection  ; section 14.10 of [RFC2616] 
            / Expect ; section 14.20 of [RFC2616] 
            
 DSC-SendReportReq-Body = ReportRequest ; section 3.10.5.1.1.1

RequestBody也找到了JSON描述

 {
     "title": "SendReport request schema",
     "type": "object",
     "properties": {
         "JobId": {
             "type": [ "string", "null" ],            
             "required": "true"
         },
         "OperationType": {
             "type": [ "string", "null" ]
         },
         "RefreshMode": {
             "enum": [ "Push", "Pull" ]
         },
         "Status": {
             "type": [ "string", "null" ]
         },
         "LCMVersion": {
             "type": [ "string", "null" ]
         },
         "ReportFormatVersion": {
             "type": [ "string", "null" ]
         },
         "ConfigurationVersion": {
             "type": [ "string", "null" ]
         },
         "NodeName": {
             "type": [ "string", "null" ]
         },        
         "IpAddress": {
             "type": [ "string", "null" ]
         },
         "StartTime": {
             "type": [ "string", "null" ]
         },
         "EndTime": {
             "type": [ "string", "null" ]
         },
         "RebootRequested": {
             "enum": [ "True", "False" ]
         },
         "Errors": {
             "type": [ "string", "null" ]
         },
         "StatusData": {
             "type": [ "string", "null" ]
         },
         "AdditionalData": {
             "type": "array",
             "required": false,
             "items": [
                 {
                     "type": "object",
                     "required": true,
                     "properties": {
                         "Key": {
                             "type": "string",
                             "required": true
                         },
                         "Value": {
                             "type": "string",
                             "required": true
                         }
                     }
                 }
             ]
         }
     }
 }

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dscpm/4cd205ec-5b1c-426e-8176-d5e02a91106b

好的，有了以上的铺垫，我们就开始发个普通的HTTP请求吧。

按照上面的JSON描述，JobId是必须的，其他字段可以不传入或者为NULL的，可以我只传入JobId的时候，数据库并没有插入任何数据，但是却响应HTTP 200, 还是提示SavedReport。（这不是坑爹呢么？！）
经过我的验证，NodeName设置上之后，就可以成功入库了。

写入成功，读取当然可以直接读数据库，或者写脚本：https://docs.microsoft.com/en-us/powershell/dsc/pull-server/reportserver?view=dsc-1.1#getting-report-data
但凡认真看下这个，GET请求这么发送，POST还要那么复杂的去读协议？

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