Return an object variable from a script - Azure YAML pipelines - azure

Question

Consider the following simplified pipeline:
### template.yml ###
parameters:
- name: "tables"
type: object
default: {}
steps:
- ${{ each table in parameters.tables }}:
- task: BackupTask#0
displayName: "Backup ${{ table }}"
### pipeline.yml ###
- template: template.yml
parameters:
tables:
- "table1"
- "table2"
- "table3"
- "table4"
- "table5"
What I would like is that the list of tables are generated with a bash script instead of having to write them by hand. So every time a new table is created it gets automatically backed up by the pipeline.

Answer 1

As a workaround, we can create another pipeline. In this pipeline, we add two powershell tasks. In the first task, we set a variable with tables as the value.
- task: PowerShell#2
inputs:
targetType: 'inline'
script: 'Write-Host "##vso[task.setvariable variable=list]table1,table2,table3"'
In the second task, we use rest api to trigger the pipeline.yml pipeline. In the request body, we use the variable set in the first task as the value of the template parameter.
- task: PowerShell#2
inputs:
targetType: 'inline'
script: |
$token = "PAT"
$url="https://dev.azure.com/{org}/{pro}/_apis/pipelines/{pipelineId}/runs?api-version=5.1-preview"
$token = [System.Convert]::ToBase64String([System.Text.Encoding]::ASCII.GetBytes(":$($token)"))
$JSON = #'
{
"templateParameters": {
"tab":"[$(list)]"
},
}
'#
$response = Invoke-RestMethod -Uri $url -Headers #{Authorization = "Basic $token"} -Method Post -Body $JSON -ContentType application/json
Below is my test sample:
### pipeline.yml ###
parameters:
- name: tab
type: object
default: {}
pool:
vmImage: 'ubuntu-latest'
steps:
- template: template1.yml
parameters:
tables: ${{ parameters.tab }}
template.yml:
### template1.yml ###
parameters:
- name: "tables"
type: object
default: {}
steps:
- ${{ each table in parameters.tables }}:
- task: PowerShell#2
inputs:
targetType: 'inline'
script: echo "${{ table }}"
Then we run the newly created pipeline to trigger the pipeline.yml pipeline, get the result: