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"""Main module of kytos/pathfinder Kytos Network Application.""" |
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import pathlib |
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from threading import Lock |
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from typing import Generator |
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from kytos.core import KytosNApp, log, rest |
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from kytos.core.helpers import load_spec, validate_openapi |
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from kytos.core.rest_api import (HTTPException, JSONResponse, Request, |
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get_json_or_400) |
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from kytos.core.retry import before_sleep |
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from napps.kytos.pathfinder.graph import KytosGraph |
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from tenacity import (retry, retry_if_exception_type, stop_after_attempt, |
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wait_fixed) |
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from .exceptions import LinkNotFound |
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class Main(KytosNApp): |
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""" |
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Main class of kytos/pathfinder NApp. |
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This class is the entry point for this napp. |
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""" |
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spec = load_spec(pathlib.Path(__file__).parent / "openapi.yml") |
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def setup(self): |
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"""Create a graph to handle the nodes and edges.""" |
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self.graph = KytosGraph() |
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self._topology = None |
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self._lock = Lock() |
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def execute(self): |
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"""Do nothing.""" |
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def shutdown(self): |
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"""Shutdown the napp.""" |
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def _filter_paths_le_cost(self, paths, max_cost): |
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"""Filter by paths where the cost is le <= max_cost.""" |
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if not max_cost: |
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return paths |
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return [path for path in paths if path["cost"] <= max_cost] |
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def _non_excluded_edges(self, links: list[str]) -> list[tuple[str, str]]: |
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"""Exlude undesired links. It'll return the remaning edges.""" |
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endpoints: list[tuple[str, str]] = [] |
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if not self._topology: |
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return endpoints |
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endpoint_ids = self._map_endpoints_from_link_ids(links) |
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for edge in self.graph.graph.edges: |
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if edge not in endpoint_ids: |
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endpoints.append(edge) |
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return endpoints |
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def _map_endpoints_from_link_ids(self, link_ids: list[str]) -> dict: |
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"""Map endpoints from link ids.""" |
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endpoints = {} |
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for link_id in link_ids: |
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try: |
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link = self._topology.links[link_id] |
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endpoint_a, endpoint_b = link.endpoint_a, link.endpoint_b |
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endpoints[(endpoint_a.id, endpoint_b.id)] = link |
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except KeyError: |
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pass |
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return endpoints |
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def _find_all_link_ids( |
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self, paths: list[dict], link_ids: list[str] |
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) -> Generator[int, None, None]: |
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"""Find indexes of the paths that contain all link ids.""" |
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endpoints_links = self._map_endpoints_from_link_ids(link_ids) |
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if not endpoints_links: |
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return None |
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endpoint_keys = set(endpoints_links.keys()) |
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for idx, path in enumerate(paths): |
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head, tail, found_endpoints = path["hops"][:-1], path["hops"][1:], set() |
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for endpoint_a, endpoint_b in zip(head, tail): |
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if (endpoint_a, endpoint_b) in endpoints_links: |
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found_endpoints.add((endpoint_a, endpoint_b)) |
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if (endpoint_b, endpoint_a) in endpoints_links: |
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found_endpoints.add((endpoint_b, endpoint_a)) |
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if found_endpoints == endpoint_keys: |
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yield idx |
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return None |
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@rest("v3/", methods=["POST"]) |
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@validate_openapi(spec) |
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def shortest_path(self, request: Request) -> JSONResponse: |
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"""Calculate the best path between the source and destination.""" |
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data = get_json_or_400(request, self.controller.loop) |
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if not isinstance(data, dict): |
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raise HTTPException(400, detail=f"Invalid body value: {data}") |
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undesired = data.get("undesired_links", []) |
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spf_attr = data.get("spf_attribute", "hop") |
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spf_max_paths = data.get("spf_max_paths", 2) |
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spf_max_path_cost = data.get("spf_max_path_cost") |
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mandatory_metrics = data.get("mandatory_metrics", {}) |
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flexible_metrics = data.get("flexible_metrics", {}) |
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minimum_hits = data.get("minimum_flexible_hits") |
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log.debug(f"POST v2/ payload data: {data}") |
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try: |
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with self._lock: |
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self._get_latest_topology() |
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graph = self.graph.graph |
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if undesired: |
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non_excluded_edges = self._non_excluded_edges(undesired) |
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graph = graph.edge_subgraph(non_excluded_edges) |
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if any([mandatory_metrics, flexible_metrics]): |
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paths = self.graph.constrained_k_shortest_paths( |
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data["source"], |
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data["destination"], |
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weight=self.graph.spf_edge_data_cbs[spf_attr], |
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k=spf_max_paths, |
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graph=graph, |
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minimum_hits=minimum_hits, |
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mandatory_metrics=mandatory_metrics, |
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flexible_metrics=flexible_metrics, |
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) |
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else: |
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paths = self.graph.k_shortest_paths( |
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data["source"], |
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data["destination"], |
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weight=self.graph.spf_edge_data_cbs[spf_attr], |
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k=spf_max_paths, |
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graph=graph, |
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) |
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paths = self.graph.path_cost_builder( |
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paths, |
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weight=spf_attr, |
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) |
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log.debug(f"Found paths: {paths}") |
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except TypeError as err: |
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raise HTTPException(400, str(err)) |
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except LinkNotFound as err: |
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log.error(f"Link {err.link} not found in pathfinder graph.") |
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raise HTTPException(409, str(err)) |
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paths = self._filter_paths_le_cost(paths, max_cost=spf_max_path_cost) |
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log.debug(f"Filtered paths: {paths}") |
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return JSONResponse({"paths": paths}) |
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@retry( |
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stop=stop_after_attempt(3), |
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wait=wait_fixed(1), |
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retry=retry_if_exception_type(LinkNotFound), |
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before_sleep=before_sleep, |
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reraise=True, |
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) |
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def _get_latest_topology(self): |
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"""Get the latest topology from the topology napp.""" |
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try: |
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topology_napp = self.controller.napps[("kytos", "topology")] |
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except KeyError: |
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log.warning("Failed to get topology napp for forcing topology update.") |
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return |
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topology = topology_napp.get_latest_topology() |
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self._update_to_topology(topology) |
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def _update_to_topology( |
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self, |
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topology |
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): |
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if self._topology is topology: |
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return |
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self.graph.update_topology(topology) |
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self._topology = topology |
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switches = list(topology.switches.keys()) |
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links = list(topology.links.keys()) |
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log.debug(f"Topology graph updated with switches: {switches}, links: {links}.") |
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kytos-ng /
pathfinder
