在使用ansible "win_shell“模块时，”不能对空值表达式调用方法“

Question

我正在使用ansible win_shell模块在windows主机上运行以下命令，但收到错误“您不能在空值表达式上调用方法”

cmd:-

  - name: Get ASG Instance id
    win_shell: |
      $ASG=(Get-ASAutoScalingGroup -AutoScalingGroupName "{{ environment_name }}-asg v2").Instances | findstr \"InstanceId InService\" 
      $InstanceId=(echo $ASG) | findstr InstanceId 
      $InService=(echo $InstanceId | %{ $_.Split(':')[1]; }).replace(' ','')
    register: InService

note:- using {{ environment_name }} as a variable.

CircleCI作业失败，错误如下；

amazon-ebs:     "cmd": "$ASG=(Get-ASAutoScalingGroup -AutoScalingGroupName \"dev-asg-v2\").Instances | findstr \"InstanceId InService\" $InstanceId=(echo $ASG) | findstr 'InstanceId' $InService=(echo $InstanceId | %{ $_.Split(':')[1]; }).replace(' ','')",
    amazon-ebs:     "delta": "0:00:12.531289",
    amazon-ebs:     "end": "2020-02-12 12:12:35.640112",
    amazon-ebs:     "msg": "non-zero return code",
    amazon-ebs:     "rc": 1,
    amazon-ebs:     "start": "2020-02-12 12:12:23.108822",
    amazon-ebs:     "stderr": "You cannot call a method on a null-valued expression.\r\nAt line:1 char:291\r\n+ ... d' $InService=(echo $InstanceId | %{ $_.Split(':')[1]; }).rep ...\r\n+                                                  ~~~~~~~~~~~~~~~~\r\n    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException\r\n    + FullyQualifiedErrorId : InvokeMethodOnNull\r\n \r\nYou cannot call a method on a null-valued expression.\r\nAt line:1 char:65\r\n+ ... ing $false; $ASG=(Get-ASAutoScalingGroup -AutoScalingGroupName \"d ...\r\n+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\r\n    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException\r\n    + FullyQualifiedErrorId : InvokeMethodOnNull",
    amazon-ebs:     "stderr_lines": [
    amazon-ebs:         "You cannot call a method on a null-valued expression.",
    amazon-ebs:         "At line:1 char:291",
    amazon-ebs:         "+ ... d' $InService=(echo $InstanceId | %{ $_.Split(':')[1]; }).rep ...",
    amazon-ebs:         "+                                                  ~~~~~~~~~~~~~~~~",
    amazon-ebs:         "    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException",
    amazon-ebs:         "    + FullyQualifiedErrorId : InvokeMethodOnNull",
    amazon-ebs:         " ",
    amazon-ebs:         "You cannot call a method on a null-valued expression.",
    amazon-ebs:         "At line:1 char:65",
    amazon-ebs:         "+ ... ing $false; $ASG=(Get-ASAutoScalingGroup -AutoScalingGroupName \"d ...",
    amazon-ebs:         "+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~",
    amazon-ebs:         "    + CategoryInfo          : InvalidOperation: (:) [], RuntimeException",
    amazon-ebs:         "    + FullyQualifiedErrorId : InvokeMethodOnNull"
    amazon-ebs:     ],
    amazon-ebs:     "stdout": "",
    amazon-ebs:     "stdout_lines": []
    amazon-ebs: }

Answer 1

这通常意味着调用方法的变量是null。这意味着由于脚本问题而从未设置过变量

您将能够通过查看您在Ansible上调用的脚本来进一步调试它遇到问题的地方：At line:1 char:291。这似乎是这些变量之一：

$InService=(echo $InstanceId | %{ $_.Split(':')[1]; })

尝试直接在主机上运行该脚本以了解更多信息。