Use Azure DevOps variable in parameters section in azure pipeline - azure

Question

I have a DevOps variable group with a variable like that: VARIABLE=['a', 'b', 'c'].
Then in Azure pipeline, there is a parameter like that:
parameters:
- name: parameter_test
displayName: 'Test paramter'
type: string
default: a
values:
- a
- b
- c
I want to use the variable instead of the hardcoded list, since it's present in multiple pipelines. Tried this, but docs say I can't use expressions in parameters section:
parameters:
- name: parameter_test
displayName: 'Test paramter'
type: string
default: a
values:
- ${{ each group in variables.VARIABLE }}:
- ${{ group }}
Have you ever tried things like that or have any idea how to parametrize it?
Thanks for any help!

Answer 1

According to this document Variable groups for Azure Pipelines - Azure Pipelines | Microsoft Docs, to reference a variable group, use macro syntax or a runtime expression, therefore the parameter cannot be defined with the value of variable from a variable group.
Instead of defining the parameter with the value of the variable in a variable group, you may consider using a core YAML to transfer the parameter/variable value into a YAML Template. Kindly refer to the below sample YAML pipeline.
# Core YAML
trigger:
- none
pool:
  vmImage: ubuntu-latest
variables:
- name: Variable_core
  value: b
parameters:
- name: Parameter_core
  default: c
  values:
    - a
    - b
    - c
steps:
  - template: Parameters.yml
    parameters:
      parameter_test_Azure_Repos_1: ${{ variables.Variable_core }}
      parameter_test_Azure_Repos_2: ${{ parameters.Parameter_core }}
# Parameters.yml from Azure Repos
parameters:
- name: parameter_test_Azure_Repos_1
  displayName: 'Test Parameter 1 from Azure Repos'
  type: string
  default: a
- name: parameter_test_Azure_Repos_2
  displayName: 'Test Parameter 2 from Azure Repos'
  type: string
  default: a
steps:
- script: |
    echo ${{ parameters.parameter_test_Azure_Repos_1 }}
    echo ${{ parameters.parameter_test_Azure_Repos_2 }}

Answer 2

All non yaml files is not recommended as this is not as code, very difficult to check & audit & versionning, so as to variable group, release pipeline etc.
Azure pipeline has indeed some limitations, we can reuse the variables but not the parameters.
If I was you, even multiple pipelines use the same parameter, I will still "hard code" this directly in the pipelines just like what you wrote:
parameters:
- name: parameter_test
displayName: 'Test paramter'
type: string
default: a
values:
- a
- b
- c