Use query-time variables in pipeline YAML - azure-devops

Question

I have set up a pipeline with variables users can enter using the UI like this:
UI for userinput of variable called 'forceRelease'
I now want to use this variable in the pipeline yaml inside an if-statement like this:
jobs:
- job: Demo
steps:
- ${{ if eq(variables['forceRelease'], 'true') }}:
...some more stuff...
This does'nt work. I've tried different approaches but could not find the right syntax.
If I use the variable inside a condition, it works fine. Like this:
jobs:
- job: MAVEN_Build
- task: Bash#3
condition: eq(variables['forceRelease'], 'true')
I also tried to map the variable inside the variables block to a new pipeline variable like this:
variables:
isReleaseBranch: ${{ startsWith(variables['build.sourcebranch'],'refs/heads/pipelines-playground') }}
isForceRelease: $(forceRelease)
The first variable using 'build.sourcebranch' works fine. My approach using forceRelease doesnt work :(
Any ideas would be appreciated!
Cheers,
Dirk

Answer 1

AFAIK this is working as intended. User set variables are not expanded during parsing of the template.
You can read more on pipeline processing here:
https://learn.microsoft.com/en-us/azure/devops/pipelines/process/runs?view=azure-devops
You should instead use parameters.
parameters:
- name: "forceRelease"
type: boolean
default: "false"
- name: "someOtherParameter"
type: string
default: "someValue"
stages:
- ${{ if eq(parameters['forceRelease'], true)}}:
- stage: build
jobs:
- job: bash_job
steps:
- task: Bash#3
inputs:
targetType: 'inline'
script: |
# Write your commands here
And then when you run the pipeline you have the option to enable the parameter forceRelease or add someOtherParameter string.