In YAML is it possible to supply a template json file for appsettings

I am adding some appsettings for a function app in YAML:

steps:
- download: current
  displayName: Download app artifact
  artifact: app
- task: AzureAppServiceSettings@1
  displayName: Azure App Service Settings
  inputs:
    azureSubscription: ssubscription
    appName: appname
    appSettings: |
      [
        {
          "name": "VarOne",
          "value": "$(VAR_ONE)",
          "slotSetting": false
        },
        {
          "name": "VarTwo",
          "value": "$(VAR_TWO)",
          "slotSetting": false
        },
        {
          "name": "VarThree",
          "value": "$(VAR_THREE)",
          "slotSetting": false
        }
      ]

Is it possible to provide a template json file for appsettings? Something like:

appSettings: templates\appSettings.json

Is it possible to provide a template json file for appsettings?

According to the Azure App Service Settings v1 task Inputs, the input appSettings is a string, so we cannot use a template json file for appsettings field.

However, you can consider referring the step templates with parameters to use a template appSettings.yml. This way, you only need to change the template appSettings.yml when you want to update the appSettings.

templates/appSettings.yml:

parameters:
- name: appSettings
  type: object
  default:
    [
      {
        "name": "key1",
        "value": "value111",
        "slotSetting": false
      },
      {
        "name": "key2",
        "value": "value222",
        "slotSetting": true
      }
    ]
steps:
- task: AzureAppServiceSettings@1
  displayName: Azure App Service Settings
  inputs:
    azureSubscription: 'subscription'
    appName: 'appname'
    resourceGroupName: 'GroupName'
    appSettings: '${{ convertToJson(parameters.appSettings) }}'

main YAML file:

trigger:
- none

pool:
  vmImage: windows-latest

steps:
- other steps
- template: templates/appSettings.yml # Template reference
- other steps

If your appSettings.json file is from the Download app artifact task, the above may not work. In this case, you can use the way mentioned in Rui's answer that using an AzureCLI task with the az webapp config appsettings set command.

Sample YAML:

trigger:
- none

pool:
  vmImage: windows-latest

steps:
- download: current
  displayName: Download app artifact
  artifact: app
- task: AzureCLI@2
  inputs:
    azureSubscription: 'subscription'
    scriptType: 'batch'
    scriptLocation: 'inlineScript'
    inlineScript: |
      az webapp config appsettings set --resource-group groupname --name appname --settings "@templates/appSettings.json"