Az Function Consumption plan reverts production slot few minutes after swapping slots (Premium plan doesn't)?

Question

I've got an Azure Function setup to deploy (via GitHub actions for CD) to my staging slot... works as expected. Once I've ensured everything looks good, I swap the slots using the Azure CLI. Again, everything looks good and is running as expected in the production slot.

swap-deployment-slots:  
  name: Swap Azure Function deployment slots  
  runs-on: ubuntu-latest  
  needs: update-prod-slot-settings  
  steps:  
    ######################################################################  
    # login to Azure CLI via service principal  
    ######################################################################  
    - name: Login to Azure  
      run: az login --service-principal --tenant $AZURE_BOT_TENANT_ID --username $AZURE_BOT_CLIENT_ID --password $AZURE_BOT_CLIENT_SECRET  
      env:  
        AZURE_BOT_TENANT_ID: ${<!-- -->{ env.AZURE_BOT_TENANT_ID }}  
        AZURE_BOT_CLIENT_ID: ${<!-- -->{ env.AZURE_BOT_CLIENT_ID }}  
        AZURE_BOT_CLIENT_SECRET: ${<!-- -->{ secrets.AZURE_BOT_CLIENT_SECRET }}  
  
    ######################################################################  
    # swap deployment slots  
    ######################################################################  
    - name: Swap staging & production deployment slot  
      run: |  
        az functionapp deployment slot swap --resource-group $AZURE_FUNCTION_APP_RESOURCE_GROUP --name $AZURE_FUNCTION_APP_NAME --slot $AZURE_FUNCTION_APP_STAGING_SLOT --target-slot $AZURE_FUNCTION_APP_PRODUCTION_SLOT  
      env:  
        AZURE_FUNCTION_APP_RESOURCE_GROUP: ${<!-- -->{ env.AZURE_FUNCTION_APP_RESOURCE_GROUP }}  
        AZURE_FUNCTION_APP_NAME: ${<!-- -->{ env.AZURE_FUNCTION_APP_NAME }}  
        AZURE_FUNCTION_APP_STAGING_SLOT: ${<!-- -->{ env.AZURE_FUNCTION_APP_STAGING_DEPLOYMENT_SLOT }}  
        AZURE_FUNCTION_APP_PRODUCTION_SLOT: production  

*Ignore the HTML comments in the above snippet... something with question editor is generating those... this does work... *

Just to verify, when I inspect the function in the portal ([function app] > Functions > [select function] > Code + Test), I can see the contents of the function.json file.

However, after a few minutes, with no changes applied, all the files disappear from the production deployment slot. Going back to the same Code + Test interface, the file selector is empty:

This only happens when I'm testing using an Azure Function App on the consumption plan... this doesn't happen when I try this using the Premium plan. From my research, I can't find anything that would trigger this auto-rollback.

• is this expected?
• am I missing something?

Answer 1

This is not a complete answer - just a report of the same thing and a suggestion to try the Windows Consumption Plan instead. The commenting system seemed to be down when I posted this

I think I might be hitting the same issue.

Here's what I'm doing:

• create a new linux consumption plan on the azure portal
• create a slot called "staging"
• deploy a test function to the staging slot, and confirm that it's working with postman.
• use the azure portal to trigger a swap with production (this is different from what @Andrew Connell did but it appears to yield the same result).
• the portal indicates that the swap succeeded, and if you view the logs in Deployment Slots > Logs, everything I can see there shows "Success", too.

When I try out the test function for the production slot, I get 404 errors, and I don't see my test function in the azure portal in the production slot. The function is still in the "staging" slot as if the swap never occurred.

When I try the same thing with a windows consumption plan, everything works as expected.

In the docs, staging slots for Linux Consumption Plan functions are listed as "Preview" (not GA) status: https://learn.microsoft.com/en-us/azure/azure-functions/functions-deployment-slots#support-levels

I wonder if this is a bug associated with the preview? I'm happy to file it somewhere and provide more details/logs.