Azure DevOps YAML: compare two variables - azure-devops

Question

To determine which parameter value (my_param) I want to pass to a template (my-template.yml), I would like to compare two variables (var1 and var2) in my YAML pipeline.
- template: my-template.yml
parameters:
${{ if eq(variables.var1, variables.var2) }}:
my_param: 'abc'
${{ else }}:
my_param: 'xyz'
I tested this with different values for var1 and var2 (defined in a DevOps variable group/library). No matter what I put as variable values (whether or not they are equal), the "else" case is always triggered even if both variables have the same value. What am I missing?

Answer 1

Based on my test, there is no direct way to compare two variables in library->variable group.
So I suggest you set another variable 'compare' to previously compare the values of the two variables in the variable group.
Example:
In variablegroup 'MyVarGroup', I have var1 'SomeNumber' and var2 'samplevariable'. I now set var3 'compare', if var1=var2, I set var3 value '0', otherwise other different number.
You could also set it as true if the two variables are the same and false if they are different.
Here are my sample:
mytemplate.yml:
parameters:
name: my_param
type: string
steps:
- task: PowerShell#2
inputs:
targetType: 'inline'
script: echo "${{ parameters.my_param }}"][1]][1]
azure-pipelines.yml:
trigger:
- master
variables:
- group: MyVarGroup
- name: para
value: $[replace(replace('True',eq(variables['compare'], '0'), 'abc'),'True','xyz')]
steps:
- task: PowerShell#2
inputs:
targetType: 'inline'
script: |
echo "$(SomeNumber)"
echo "$(samplevariable)"
echo "$(compare)"
echo "$(para)"
- template: mytemplate.yml
parameters:
my_param: $(para)
If var3 compare is '0',then I will get 'abc' in the template output.
[![enter image description here][1]][1]
Otherwise, I will get 'xyz'
[![enter image description here][2]][2]
I hope it could do some help.
[1]: https://i.stack.imgur.com/1uYU6.png
[2]: https://i.stack.imgur.com/yeRy4.png