tasks: retry tasks on failure

[morpheu]

Since most RpaaS API operations are asynchronous , maybe its a good idea implement retry on celery tasks. Today the only way available is remove instance and create it again :(

[sanchezg]

Hi! I can take this issue if it's ok. Could you address me which tasks do you want to be retried if there's an error?

[morpheu]

Hi @sanchezg, there are 3 tasks that need retry, at this moment: NewInstanceTask RemoveInstanceTask, ScaleInstanceTask. The first two are a bit more complicated to address cause both of them are related to rollback processes. Scale task could be a good starting point in this issue 👍