Azure DevOps Conditional String Variables

Question

I've got a pipeline I've created that deploys some app settings to all our websites (multiple per file), and I'm trying to conditionally set a variable within the JSON structure without any sort of anti-patterns.

For conditional variables, all we have this syntax:

${{ if endsWith('EXISTING_STRING','MATCH_STRING') }}:

${{ else }}:

This syntax assumes that you're going to put the entirety of the string after condition, though. If my JSON structure is 50 lines long, I don't want to do that. Is there a way to do this without that cluttered code, whilst avoiding any sort of anti-patterns as well?

Here's the Azure Piplines Module:

- task: AzureAppServiceSettings@1
displayName: 'Deploy App Settings'
inputs:
  azureSubscription: "${{ parameters.resource_group_name }}"
  appName: "wz${{ parameters.default_environment }}"
  resourceGroupName: "${{ parameters.resource_group_name }}"
  appSettings: |
     [
     {
        "name": "LaunchUrl",
        "value": "False", 
        /* ^^^^ 
          Value I want to be conditional based off:
            if endsWith( parameters['default_environment'], 'matchString'
          The resulting string also contains parameters.default_environment FYI
        */
        "slotSetting": true
    },
    {
        "name": "DisableFHIR",
        "value": "False",
        "slotSetting": true
    },
    ...

Thanks

bryanbcook · Accepted Answer · 2022-02-14 22:42:49Z

2

Putting conditionals inside a string literal is unfortunately not supported. However, one technique my team uses is define our JSON values as a string parameter and populate it with variables that are evaluated at runtime.

parameters:
- name: appSettings
  type: string
  default: |
    '[
       { 
         "name": "appSetting1",
         "value": "$(appSetting1)",
         "slotSetting": "true"
       }
    ]'

Personally, I like to go one further and define them as a yaml parameter and then use the convertToJson expression. This avoids the potential for malformed JSON and I can also put comments in the YAML.

parameters:
- name: resource_group_name
  type: string

- name: appSettings
  type: object
  default:
    - name: 'LaunchUrl'
      value: '$(launchUrl)'
      slotSetting: true
    - name: 'DisableFHIR'
      value: 'false'
      slotSetting: true

job:
  variables:

    ${{ if endsWith('prd', parameters.resource_group_name) }}:
       launchUrl: https://production.dot.com
    ${{ else }}:
       launchUrl: http://somewhere.else.com

  steps:

  - task: AzureAppServiceSettings@1
    inputs:
      azureSubscription: "${{ parameters.resource_group_name }}"
      appName: "wz${{ parameters.default_environment }}"
      resourceGroupName: "${{ parameters.resource_group_name }}"
      appSettings: ${{ convertToJson(parameters.appSettings) }}

answered Feb 14, 2022 at 22:42

bryanbcook

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1 Comment

mochsner Over a year ago

Hmm I definitely like this convertToJson approach! Assuming this doesn't cause any issues with evaluating runtime parameters in the end-result, this sounds like it might solve my issues! I'll follow up in the next week and get you some well awaited credit haha. Ty!

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