How to ensure kubernetes cronjob does not restart on failure

It turns out that you have to set a backoffLimit: 0 in combination with restartPolicy: Never in combination with concurrencyPolicy: Forbid.

backoffLimit means the number of times it will retry before it is considered failed. The default is 6.

concurrencyPolicy set to Forbid means it will run 0 or 1 times, but not more.

restartPolicy set to Never means it won't restart on failure.

You need to do all 3 of these things, or your cronjob may run more than once.

spec:
  concurrencyPolicy: Forbid
  failedJobsHistoryLimit: 1
  jobTemplate:
    metadata:
      creationTimestamp: null
    spec:
      [ADD THIS -->]backoffLimit: 0
      template: 
      ... MORE STUFF ...