swch_optimiser

A Python wrapper around MiniZinc for solving system reconfiguration problems: given the current mapping of pods (microservice instances) to nodes plus an application-specific rule set, SwchOptimiser finds an optimal next mapping (including scaling nodes/pods up or down) and turns the result into a list of concrete actions (create_ms, destroy_ms, create_node, destroy_node).

Application-specific constraints and the optimisation goal are written in MiniZinc and passed in as a rule string; the library supplies the shared system parameters (sys_*) that every rule set builds on.

Requirements

• Python 3.12+
• A working MiniZinc installation with the Gecode solver available on your system (minizinc --solvers should list Gecode)

Installation

This project uses Poetry:

poetry install

Usage

from swch_optimiser import SwchOptimiser

rule = r"""
    % --- APPLICATION CONSTANTS ---
    float: threshold_min_node_load;
    float: threshold_max_node_load;
    % --- APPLICATION PARAMETERS ---
    array[1..sys_node_count_actual] of float: node_load;

    constraint sys_pod_count_next >= 1;
    % ... additional constraints ...

    var int: loss = 100 * sum(p in 1..sys_pod_count_max)(bool2int(sys_mapping_next[p] != sys_mapping_actual[p]));
    solve minimize loss;
    """

optimiser = SwchOptimiser(rule, mslist=["my-service"])
if optimiser.get_error() is not None:
    raise SystemExit(optimiser.get_error())

optimiser.add_input_system({
    "sys_pod_count_max": 14,
    "sys_node_count_max": 10,
    "sys_node_count_actual": 3,
    "sys_mapping_actual": [1, 1, 2, 2, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0],
})
optimiser.add_input_constants({
    "threshold_min_node_load": 40.0,
    "threshold_max_node_load": 70.0,
})
optimiser.add_input_metrics({
    "node_load": [30.0, 30.0, 30.0],
})
optimiser.validate_inputs()

result = optimiser.solve(time_limit_milliseconds=None)
if result is not None and result.solution is not None:
    for action in optimiser.generate_actions():
        print(action)

More complete, runnable examples for different use cases are in examples/:

• demo_nodescaling.py
• demo_fuelics_wastewater.py
• demo_innorenew_sound_processing.py
• demo_ust_forest_dt.py

Run any of them with:

poetry run python examples/demo_nodescaling.py

API reference

The public API is a single class, SwchOptimiser, exported from swch_optimiser.

Constructor

Input setup

Solving

Reading back results / actions

Introspection / debugging helpers

License

MIT — see LICENSE.