[BUG]: FileTransform@1 broken when trying to replace keys starting with `input* in JSON

[ProtossGP32]

Task name

FileTransform@1

Task version

1

Environment type (Please select at least one enviroment where you face this issue)

• [ ] Self-Hosted
• [X] Microsoft Hosted
• [ ] VMSS Pool
• [ ] Container

Azure DevOps Server type

dev.azure.com (formerly visualstudio.com)

Azure DevOps Server Version (if applicable)

No response

Operation system

ubuntu-latest

Task log

Starting: File transformation: test_file.json
==============================================================================
Task         : File transform
Description  : Replace tokens with variable values in XML or JSON configuration files
Version      : 1.220.0
Author       : Microsoft Corporation
Help         : https://docs.microsoft.com/azure/devops/pipelines/tasks/utility/file-transform
==============================================================================
Applying JSON variable substitution for **/test_file.json
Applying JSON variable substitution for /home/vsts/work/1/s/templates/files/test_file.json
Substituting value on key a with (string) value: This is the value for a
Substituting value on key output with (string) value: b_2 output string
Substituting value on key random with (string) value: b_2 random string
Substituting value on key output_path with (string) value: This is the value for output_path
Substituting value on key input_path with (string) value: undefined # This is correctly defined as a variables and instead appears as undefined, thus removing the key from the source JSON
JSON variable substitution applied successfully.
Finishing: File transformation: test_file.json

Relevant log output

There are no errors in the log but currently defined variables that start with `input_*` are incorrectly assigned:

Substituting value on key input_path with (string) value: undefined

Aditional info

Current configuration of the task is as follows:

stages:
  - stage: FileTransformStage
    variables:
      - template: 'templates/variables/test-file-values.yaml'
    jobs:
      - job: FileTransformJob
        steps:
          - checkout: self
            submodules: true
          # Replace variables in `test_file.json`
          - task: FileTransform@1
            displayName: "File transformation: test_file.json"
            inputs:
              folderPath: '$(Build.SourcesDirectory)/templates/files/'
              fileType: 'json'
              targetFiles: '**/test_file.json'
          # Output transformed file
          - task: Bash@3
            displayName: "Check File Transformations"
            inputs:
              targetType: 'inline'
              workingDirectory: '$(Build.SourceDirectory)'
              script: |
                echo "Showing content of $(Build.SourcesDirectory)/templates/files/test_file.json"
                cat $(Build.SourcesDirectory)/templates/files/test_file.json
                echo ""
                echo "==========================="
                echo "Checking template variables:"
                echo "input_path: $(input_path)"

test_file.json is as follows:

{
  "a": "DUMMY",
  "b": {
    "b_2": {
      "input": "DUMMY",
      "output": "DUMMY",
      "random": "DUMMY"
    },
    "b_3": {
      "input": "DUMMY",
      "output": "DUMMY",
      "random": "DUMMY"
    },
    "b_4": {
      "input": "DUMMY",
      "output": "DUMMY",
      "random": "DUMMY"
    }
  },
  "output_path": "DUMMY",
  "input_path": "DUMMY"
}

test-file-values.yaml is as follows:

variables:
  a: "This is the value for a"
  output_path: "This is the value for output_path"
  input_path: "This is the value for input_path"
  b.b_2.output: "b_2 output string"
  b.b_2.random: "b_2 random string"

When looking at the transformed file, the next bash task outputs the following:

Showing content of /home/vsts/work/1/s/templates/files/test_file.json
{
    "a": "This is the value for a",
    "b": {
        "b_2": {
            "input": "DUMMY",
            "output": "b_2 output string",
            "random": "b_2 random string"
        },
        "b_3": {
            "input": "DUMMY",
            "output": "DUMMY",
            "random": "DUMMY"
        },
        "b_4": {
            "input": "DUMMY",
            "output": "DUMMY",
            "random": "DUMMY"
        }
    },
    "output_path": "This is the value for output_path"
}
===========================
Checking template variables:
input_path: This is the value for input_path

As you can see, all defined variable keys are replaced except the ones that start with input_*, which are completely wiped from the original JSON file as FileTransform thinks that its value is undefined.

[ProtossGP32]

Hi! Any news on this bug? This right now is a dealbreaker for all of our CI pipelines

[github-actions[bot]]

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