【Azure 应用服务】Azure Function App 执行PowerShell指令[Get-Azsubscription -TenantId $tenantID -DefaultProfile $cxt]错误

问题描述

使用PowerShell脚本执行获取Azure订阅列表的指令（Get-Azsubscription -TenantId $tenantID -DefaultProfile $cxt）。在本地调试后，指令成功运行。

但是当指令并运行在Azure Function时，则出现了异常：详细的异常信息为

完成的错误信息为： "Error getting value from 'Tags' on 'Microsoft.Azure.Commands.Profile.Models.PSAzureSubscription'."

Microsoft.Azure.WebJobs.Script.Workers.Rpc.RpcException : Result: ERROR: Error getting value from 'Tags' on 'Microsoft.Azure.Commands.Profile.Models.PSAzureSubscription'.

Exception             : 
    Type           : Newtonsoft.Json.JsonSerializationException
    TargetSite     : 
        Name          : GetValue
        DeclaringType : Newtonsoft.Json.Serialization.ExpressionValueProvider
        MemberType    : Method
        Module        : Newtonsoft.Json.dll
    StackTrace     : 
   at Newtonsoft.Json.Serialization.ExpressionValueProvider.GetValue(Object target)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.CalculatePropertyValues(JsonWriter writer, Object value, JsonContainerContract contract, JsonProperty member, JsonProperty property, JsonContract& memberContract, Object& memberValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeDictionary(JsonWriter writer, IDictionary values, JsonDictionaryContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonSerializer.Serialize(JsonWriter jsonWriter, Object value, Type objectType)
   at Newtonsoft.Json.JsonConvert.SerializeObjectInternal(Object value, Type type, JsonSerializer jsonSerializer)
   at Newtonsoft.Json.JsonConvert.SerializeObject(Object value, Type type, Formatting formatting, JsonSerializerSettings settings)
   at Newtonsoft.Json.JsonConvert.SerializeObject(Object value, Formatting formatting, JsonConverter[] converters)
   at Microsoft.Azure.Commands.Common.Authentication.Models.AzureRmProfile.ToString(Boolean serializeCache)
   at Microsoft.Azure.Commands.Common.Authentication.Models.AzureRmProfile.ToString()
   at System.Management.Automation.ParameterBinderBase.CoerceTypeAsNeeded(CommandParameterInternal argument, String parameterName, Type toType, ParameterCollectionTypeInformation collectionTypeInfo, Object currentValue)
   at System.Management.Automation.ParameterBinderBase.BindParameter(CommandParameterInternal parameter, CompiledCommandParameter parameterMetadata, ParameterBindingFlags flags)
   at System.Management.Automation.CmdletParameterBinderController.BindParameter(CommandParameterInternal argument, MergedCompiledCommandParameter parameter, ParameterBindingFlags flags)
   at System.Management.Automation.CmdletParameterBinderController.BindParameter(UInt32 parameterSets, CommandParameterInternal argument, MergedCompiledCommandParameter parameter, ParameterBindingFlags flags)
   at System.Management.Automation.CmdletParameterBinderController.BindParameters(UInt32 parameterSets, Collection`1 arguments)
   at System.Management.Automation.CmdletParameterBinderController.BindCommandLineParametersNoValidation(Collection`1 arguments)
   at System.Management.Automation.CmdletParameterBinderController.BindCommandLineParameters(Collection`1 arguments)
   at System.Management.Automation.CommandProcessor.BindCommandLineParameters()
   at System.Management.Automation.CommandProcessor.Prepare(IDictionary psDefaultParameterValues)
   at System.Management.Automation.CommandProcessorBase.DoPrepare(IDictionary psDefaultParameterValues)
   at System.Management.Automation.Internal.PipelineProcessor.Start(Boolean incomingStream)
   at System.Management.Automation.Internal.PipelineProcessor.SynchronousExecuteEnumerate(Object input)
   at System.Management.Automation.PipelineOps.InvokePipeline(Object input, Boolean ignoreInput, CommandParameterInternal[][] pipeElements, CommandBaseAst[] pipeElementAsts, CommandRedirection[][] commandRedirections, FunctionContext funcContext)
   at System.Management.Automation.Interpreter.ActionCallInstruction`6.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
    Message        : Error getting value from 'Tags' on 'Microsoft.Azure.Commands.Profile.Models.PSAzureSubscription'.
    Data           : System.Collections.ListDictionaryInternal
    InnerException : 
        Type       : System.ArgumentNullException
        Message    : Value cannot be null. (Parameter 'value')
        ParamName  : value
        TargetSite : 
            Name          : ArgumentNotNull
            DeclaringType : Newtonsoft.Json.Utilities.ValidationUtils, Newtonsoft.Json, Version=12.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed
            MemberType    : Method
            Module        : Newtonsoft.Json.dll
        StackTrace : 
   at Newtonsoft.Json.Utilities.ValidationUtils.ArgumentNotNull(Object value, String parameterName)
   at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
   at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings)
   at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value)
   at Microsoft.Azure.Commands.Common.Authentication.Abstractions.AzureSubscriptionExtensions.GetTags(IAzureSubscription subscription)
   at lambda_method(Closure , Object )
   at Newtonsoft.Json.Serialization.ExpressionValueProvider.GetValue(Object target)
        Source     : Newtonsoft.Json
        HResult    : -2147467261
    Source         : Newtonsoft.Json
    HResult        : -2146233088
CategoryInfo          : OperationStopped: (:) [], JsonSerializationException
FullyQualifiedErrorId : Newtonsoft.Json.JsonSerializationException
InvocationInfo        : 
    ScriptLineNumber : 26
    OffsetInLine     : 1
    HistoryId        : -1
    ScriptName       : D:homesitewwwrootHttpTrigger1
un.ps1
    Line             : $subs = Get-Azsubscription -TenantId $tenantID -DefaultProfile $cxt
                       
    PositionMessage  : At D:homesitewwwrootHttpTrigger1
un.ps1:26 char:1
                       + $subs = Get-Azsubscription -TenantId $tenantID -DefaultProfile $cxt
                       + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    PSScriptRoot     : D:homesitewwwrootHttpTrigger1
    PSCommandPath    : D:homesitewwwrootHttpTrigger1
un.ps1
    CommandOrigin    : Internal
ScriptStackTrace      : at <ScriptBlock>, D:homesitewwwrootHttpTrigger1
un.ps1: line 26

问题分析及临时解决方案

对比以上本地可以成功运行，而在Azure Function中确出现JSON格式解析错误，所以排查PowerShell脚本错误问题。 那么就定位在运行脚本的环境问题。

第一步：排查PowerShell版本，及az 模块的版本

通过 $PSVersionTable 打出PowerShell版本，通过 Get-InstalledModule -name az 和 Get-InstalledModule -name az.* 打印出当前环境的版本号。

 经过对比，发现本地VM与Azure Function中Powershell和az 模块的版本都不同.  

第二步：寻找临时的解决方案

由于Azure Function中PowerShell的版本从平台级别无法更改（可以修改PS脚本中所使用的az模块版本，修改方式见附件一）。所以主要的寻找发向为：基于现在的版本，从Get-Azsubscription指令本身来寻找Workaround呢？查看Get-Azsubscription指令，发现它使用的是当前登录用户的权限去获取所有的订阅号，指定TenantID是表明只获取当前TenantID下的所有订阅号。而参数DefaultProfile也是只携带用户认证信息，与当前登录的用户所有的认证信息重复。

Get-AzSubscription	Get subscriptions that the current account can access
-TenantId	Specifies the ID of the tenant that contains subscriptions to get
-DefaultProfile	The credentials, tenant and subscription used for communication with azure

如果不添加-DefaultProfile参数，是否同样由异常呢？ 经过验证执行成功并返回结果正确。所以作为Workaround的代码为：

# Write to the Azure Functions log stream.
Write-Host "PowerShell HTTP trigger function processed a request."

$User = "XXXXXXXXXXXXXxxxxxxxx"
$PWord = ConvertTo-SecureString -String "XXXXXXXXXXXXXxxxxxxxx" -AsPlainText -Force
$Credential = New-Object System.Management.Automation.PSCredential($User, $PWord)

Connect-AzAccount -Environment AzureChinaCloud -Credential $Credential

Write-Host "login successfully"

$tenantID = "xxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
$cxt = Set-AzContext -Tenant $tenantID
write-host $cxt


write-host "no defaultprofile"
Write-Host "Get-Azsubscription -TenantId $tenantID"
#$subs = Get-Azsubscription -TenantId $tenantID -DefaultProfile $cxt
Get-Azsubscription -TenantId $tenantID
write-host "========================="
write-host $subs

附件一：在Azure Funciton中修改az的版本号为5.2.0, 问题也得到解决。

在Azure Function 门户页面，点击“App Service Editor (Preview)” 目录，进入Editor页面，在文件requirements.psd1文件中，修改az的版本号为5.2.0. 保存后，回到Azure Function页面。重启Function. 修改页面如下：

结论: 解决办法有两种

1. 修改az的版本号为5.2.0，修改办法见附件一
2. 修改Get-Azsubscription指令，去掉参数 -DefaultProfile $cxt

参考资料

Get-AzSubscription ： https://docs.microsoft.com/en-us/powershell/module/az.accounts/get-azsubscription?view=azps-6.2.0