Preliminary remark: The word replica means repetition or copy for me, but:
When someone speaks of "one replica", does that mean one instance or two instances in total? Interestingly, I have come across the use of the former case and this makes me a little insecure. Based on the second case, would one speak of "zero replicas" if there is only one app or instance in total?
Sorry if that question seems a bit vague. Example time. My app or instance has 8 different containers in 8 different pods.
+------------+--------------+--------------+
| #container | case 1 | case 2 |
+------------+--------------+--------------+
| 8 x 1 | "1 replica" | "0 replicas" |
| 8 x 2 | "2 replicas" | "1 replica" |
| 8 x 3 | "3 replicas" | "2 replicas" |
| ... | ... | ... |
+------------+--------------+--------------+
The question whether the word replica refers to a single container/pod or to the whole app is not important here (it is equivalent), because I will replicate each different container/pod of the 8 containers/pods with the same number. I would like to know if you would rather use case 1 or case 2 (in discussions among colleagues), or if the numbering is one-based or zero-based. Please mark the question as opinion-based, if necessary.