How to update application settings of an Azure Functions App in Azure DevOps Pipeline

Time needed: 10 minutes

How to update application settings of Azure Functions using AzDO

1. (Optional) Configure your variable group

   Add your desired app settings as variables. Remember the name of your variable group, you’ll need it later!
   
   
   
   Alternatively, you can just define your variables as pipeline variables. But using the variable groups is often easier for centralized management, and because of the Azure Key Vault integration.
2. (Optional) “Import” your Azure DevOps variable group to your pipeline

   There’s probably a better word for this – but you can “import” or “reference” your variable groups from a lot of tasks on Azure DevOps using a syntax like shown below:
   
   
   
   This’ll enable your task to use the variables like they were defined as build pipeline variables – which is really neat!
   
   If you’re not using variable groups (i.e. you skipped the first step too and simply defined pipeline variables), you can skip this one as well.

3. Add a task that supports appSettings transformation

   Okay – so this is one step that could easily go wrong, as the way application settings are updated for Azure Functions is quite a bit different as opposed to an App Service or IIS website deployment.
   
   Instead of enabling XML/JSON transformations or some other neat and semi-automatic way of replacing application settings, you’ll need the properties that are to be overwritten to variables one by one – and you need to select the right task for the job!
   
   Aaaaand the right task is called AzureFunctionApp@1. A little bit underwhelming, I know – but the real beef comes next…
   
   (Although – if you DO like JSON instead, skip steps 3 & 4 and jump right to step 5 instead…)

4. Insert the following (which looks very redundant, but works, I assure you)

   One of the inputs this task accepts is called “appSettings.” You can overwrite app settings one by one – like follows:
   
   task: AzureFunctionApp@1
inputs:
azureSubscription: $(serviceconnection)
appSettings: '-CosmosDbConnectionString $(CosmosDbConnectionString)'
   
   Yes – in this configuration, we’re overwriting an application setting called “CosmosDbConnectionString” with whatever value comes from a variable in the mapped variable group (imported in step 2), or in the pipeline variable (takes precedence).
   
   You can obviously add multiple overwrites, and you don’t have to use variables – but most of the time you probably will want to!
5. (Alternative): You can also use the AzureAppServiceSettings task

   As Matt points out in the comments below, if you DO have your future application settings neatly packed into JSON -form, you could also use AzureAppServiceSettings task instead. Way more convenient – but I passed on this as I was not in possession of such a thing.
   
   A sample of how to use the task is below:
   
   task: AzureAppServiceSettings@1
displayName: 'Set Application Settings'
inputs:
azureSubscription: $(ServiceConnection)
appName: $(AppName)
resourceGroupName: $(ResourcGroup)
appSettings: |
[
{
"name": "MySetting",
"value": "MyValue",
"slotSetting": false
}
]