Re: [pve-devel] [PATCH qemu-server 1/2] api: return UPID in template call

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

On 10.09.21 11:26, Dominik Csapak wrote:
> Isn't this technically a breaking api change?
> 
> I.e. if someone relies on the '{data:null}' return for a successfull
> template task start, it would now break?
> 
> Not that i'm opposed to the patch (on the contrary), just wanted
> to clarify
> 

We never saw the change from null to some data, especially UPID as
breaking change.

If you argue that one asserted for null, which one can do but we simply
do not care, especially as we often did that and nobody yelled about that
practice yet, then we also must not add new parameters because once could
have asserted that their API work by asserting the return of an error code
by using an unknown parameter, i.e., that arguing is a slippery slope to
absolutely freezing development.

Breaking change in response are basically:
- change from non-null type to something else
- removal of properties without guarding such removal behind a new+
  property or similar opt-in way