fix: prevent failure when deleting cloud function with missing schedule

[crossan007]

Closes: 4795

Description

Fixes #4795 (comment)

When deletion of a pubsub.schedule Cloud Function partially fails, manual interaction is required to fully delete the function.

In my case, deletion of the Cloud Function was unpredictably failing after deleting the associated Cloud Schedule, leaving the function unable to be deleted by a deployment even with the --force CLI flag

This MR changes the behavior of Cloud Functions deployment so that a function which is supposed to have an associated schedule will be deleted if the schedule no longer exists.

Scenarios Tested

Using the latest build of master @ a54e4ff20cc0aca11d89e2f6b31c35f063918d87

1. Deploy a Cloud Function (v1) using firebase deploy
2. Confirm the function exists https://console.cloud.google.com/functions/list
3. Confirm the schedule for the function exists https://console.cloud.google.com/cloudscheduler
4. Delete the schedule associated with the function
   a. I am unsure what specific scenarios cause the schedule to be deleted without the function being deleted, but it's happened to me a number of times
   b. Notice the Trigger column in the Firebase console becomes blank:
   
5. Remove the function from the deployment source code
6. Run firebase deploy
   a. Observe the failure in the deploy logs: HTTP Error: 404, Job not found.
   b. Observe the final failure notice in the deploy logs:

   Error: There was an error deploying functions:
     Error Failed to upsert schedule function <function name> in region us-central1
   

Using the changes from this merge request

repeat steps 1-5

6. Run firebase deploy
   a. Observe the warning in the deploy logs:

   HTTP Error: 404, Job not found.
   Trigger for dispatchCampaign not found, continuing with deletion of function
   

   b. Confirm the deployment succeeds and the affected functions have been removed.

Sample Commands

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[crossan007]

@taeold and @christhompsongoogle are tagged in the associated issue

[joehan]

Thanks for the contribution! I added some early review feedback, and assigned some folks with more context on functions to give a more thorough pass.

Could you also add a changelog entry?

[joehan]

Drive by: Probably safer to just check if err.status == 404 - relying on the exact string is vulnerable to breaking in the future.

[crossan007]

I considered that; however, I wasn't sure whether the backend here may re-use the 404 status code for a scenario where we would not want to continue cleanup.

I can adjust this either way based on guidance from someone familiar with the possible failure modes here.

[joehan]

This concerns me - if the topic deletion fails for a generic reason, I don't like orphaning the resource. If we can check for specific failures (ie 404s), I'd be more comfortable with this

[joehan]

Fixes #4795