Ask HN: How to write a configurator for deploying a multi-service system?
Suppose your product manager says, package this system in such a way that we can sell our system to another customer. It will involve scaling down to varying levels (from demo version all they way up to a smaller multi-DC version for fault-tolerance), but significantly less scale than yours.
Now, although you have the experience to advise your customers about a system to achieve a specific scale, you don't want to be stuck helping them through their deployment. So you start writing a configurator that takes in a desired input transaction rate, and outputs a smaller clone of your architecture that can handle that load.
I'm looking for ideas/papers/advice on how to write such a configurator. The problem is that there are still a lot of variables, such as how many hardware servers, how many of each software server (keeping fault-tolerance in mind), their placement etc. Because each of these systems have different demands on cpu/memory/disk/network, they are inherently unequal in their effect. It is analogous to a recipe generator that spits out a recipe for a given number of people, where different components scale differently in terms of amounts and cooking time.
It is easy to describe a minimal system. Starting with the fault-tolerance criteria, one will need a minimum of a three-box cluster. One can start all the required services manually and arrive at a configuration that maximizes the TPS. Is there a nice way to compute how many of each will be required to handle double that base workload? I am thinking I'd put in as many hardware/software servers as the number the most performance bottleneck components require, and then do some elementary bin-packing of the rest of the components depending on their resource usage. If you have some guidance, pointers for me, I'd be most grateful. Thanks in advance.