Question 37430 in Ubuntu Question posted in
The official Ubuntu documentation can be found here.

Azure DevOps YAML: If-else conditions with variables from templates not working – Ubuntu

Edit 1: In the original post I have a typo: inside step #4 I used compile-time expressions which is not correct of course, and in my original pipeline I am using template expressions. Sorry for the confusion – now YAML snippets in this post are identical to my pipeline. And yes, it’s still not working.
Screenshot of execution

Because of some reason, I have some trouble while using template expressions syntax (If-else statement especially) with variables that are imported from a template. Which broking all logic of my pipeline.
So, I have a quite simple ADO Yaml pipeline:
azure-pipelines.yml

parameters:
  - name: applicationType
    type: string
    values:
    - Backend
    - Frontend
    - Others
    default: Backend

trigger: none
resources:
    repositories:
    - repository: Templates
      type: git
      name: Templates

variables:
 - name: applicationType
  value: ${{ parameters.applicationType }}
 - template: vars/vars.yml@Templates
   parameters:
     varAppType:$(applicationType)

stages:
  - stage: Test
    jobs:
      - job: Test
        pool:
          vmImage: ubuntu-latest
        steps:
        - bash: echo $(applicationType) #1
        - ${{ if eq(variables.applicationType, 'Backend') }}: #2
          - bash: echo "It is Backend" 
        - ${{ else }}:
          - bash: echo "It is something different"
        - bash: echo $(varAppType) #3
        - ${{ if eq(variables.varAppType, 'Backend') }}: #4
          - bash: echo "It is Backend" 
        - ${{ else }}:
          - bash: echo "It is something different"

And here is the snippet of vars/vars.yml which located in Templates repo:

parameters:
    - name: varAppType
      default: ''

variables:
- name: varAppType
  value: ${{ parameters.varAppType }}

Everything looks fine and straightforward, but here is what I see in logs during the run if I set applicationType as ‘Backend’:

#1 output: Backend
#2 output: It is Backend
#3 output: Backend
#4 output: It is something different

Because conditionals only work when used with template syntax I don’t even know what else I can try to do.
Its strange why ADO making such a difference between typical vars and imported from template ones, as I thought it should be working well because template syntax get processed at compile time, before runtime starts.
Maybe somebody knows how to fix this and what point I am missing with such a trivial task.
Any help would be appreciated, so thanks in advance.

Tags:

2

Answers


  1. 0

    For #4 you are using runtime expression ($[]), while for #2 – compile-time expression (${{}}). Conditional insertion can work only with compile-time expressions, that’s why #4 is not working. More info about expressions: https://learn.microsoft.com/en-us/azure/devops/pipelines/process/expressions?view=azure-devops

    To solve your problem you can try to change your pipeline in a way that you would use compile-time expressions or use condition field which is present in any step. In second option it would be possible to use runtime expressions

    Login or Signup to reply.
  2. 0

    You’re mixing different types of variables.

     - template: vars/vars.yml@Templates
   parameters:
     varAppType:$(applicationType)

    $(applicationType) is macro syntax, which is evaluated at runtime. However, template parameters are resolved at compilation time. Thus, varAppType:$(applicationType) should actually be varAppType: ${{ variables.applicationType }} (or more ideally, ${{ parameters.applicationType }}) so it can be resolved at compilation time.

    However, the mapping of parameters into variables that you’re doing is largely unnecessary. You can just reference the parameter directly as ${{ parameters.applicationType }} throughout. As such, your entire vars.yml template is unnecessary.

    Another best practices note:

    What you’re doing here:

    - bash: echo $(applicationType) is potentially dangerous. Just like SQL injection, you’re taking an arbitrary string and injecting it directly into a script. This is called a script injection vulnerability.

    The better way to handle this is to map your parameter into an environment variable and reference it as an environment variable within your script, as follows:

    - bash: echo $APP_TYPE
  env:
   APP_TYPE: ${{ parameters.applicationType }}
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search