azp: substring runtime expression is reported as unrecognised

[Viajaz]

substring as an unrecognised function when used in a runtime expression, even though the expression is valid in Azure DevOps Pipelines.

variables:
  Tag: $[ substring(variables['Build.SourceVersion'], 0, 7) ]
  ShortHash: $[ substring(variables['Build.SourceVersion'], 0, 7) ]

Unrecognized function: 'substring'. Located at position 2 within expression:  substring(variables['Build.SourceVersion'], 0, 7) 

[ChristopherHX]

Was this function added recently?

• https://learn.microsoft.com/en-us/azure/devops/pipelines/process/expressions?view=azure-devops does not mention it
• https://stackoverflow.com/questions/62343942/can-i-substring-a-variable-in-azure-pipelines
• https://developercommunity.visualstudio.com/t/add-substring-function-to-Pipelines-to-s/10720891?sort=newest&topics=visual+studio+2017
• https://developercommunity.visualstudio.com/t/add-support-substring-functions-in-azure-pipelines/1026034

Would look into this later this week, if it is available by now without any hints from documentation.

[Viajaz]

Unfortunately, I don't know when they added it, I think I've been using it since sometime last year.

Here is a test pipeline for it:

trigger: none
pr: none

variables:
  Tag: $[ substring(variables['Build.SourceVersion'], 0, 7) ]
  ShortHash: $[ substring(variables['Build.SourceVersion'], 0, 7) ]
  StaticSubstring: $[ substring('abcdef1234567890', 0, 7) ]

pool:
  vmImage: 'ubuntu-latest'

steps:
- checkout: none

- bash: |
    set -euo pipefail

    echo "Build.SourceVersion: ${SOURCE_VERSION}"
    echo "Tag: ${TAG_VALUE}"
    echo "ShortHash: ${SHORT_HASH_VALUE}"
    echo "StaticSubstring: ${STATIC_SUBSTRING_VALUE}"

    expected_short_hash="${SOURCE_VERSION:0:7}"

    if [ "${TAG_VALUE}" != "${expected_short_hash}" ]; then
      echo "##vso[task.logissue type=error]Tag did not match expected short hash '${expected_short_hash}'"
      exit 1
    fi

    if [ "${SHORT_HASH_VALUE}" != "${expected_short_hash}" ]; then
      echo "##vso[task.logissue type=error]ShortHash did not match expected short hash '${expected_short_hash}'"
      exit 1
    fi

    if [ "${STATIC_SUBSTRING_VALUE}" != "abcdef1" ]; then
      echo "##vso[task.logissue type=error]StaticSubstring did not match expected value 'abcdef1'"
      exit 1
    fi

    echo "substring runtime expressions evaluated successfully."
  displayName: 'Test: substring runtime expression'
  env:
    SOURCE_VERSION: $(Build.SourceVersion)
    TAG_VALUE: $(Tag)
    SHORT_HASH_VALUE: $(ShortHash)
    STATIC_SUBSTRING_VALUE: $(StaticSubstring)

Attached is a screenshot of it in use in an Azure DevOps Pipeline.

[ChristopherHX]

Thanks for briging this up, since I would not even tried to use such function myself.

Found a weird bug, if I use substring like you did in $[ ... ] (inclusive your example) and press validate on the online pipeline editor then I get this error.

Sorry, we were unable to validate your pipeline. Please check your YAML definition and try again

Should be very minor thing to support this very soon here as well

[Viajaz]

I must admit, I don't use the ADO Pipeline web editor so I never noticed, but the inconsistent behaviour throughout the product doesn't surprise me.

That said, all this could be a legitimate argument to simply reduce the error down to a warning stating it's not fully supported.

[ChristopherHX]

The prerelease version should resolve the problem (OpenVsx complains about an leaked secret...)