123 lines
4.2 KiB
Python
123 lines
4.2 KiB
Python
"""Flows Planner"""
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from dataclasses import dataclass, field
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from time import time
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from typing import Any, Dict, List, Optional, Tuple
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from django.core.cache import cache
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from django.http import HttpRequest
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from structlog import get_logger
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from passbook.core.models import User
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from passbook.flows.exceptions import EmptyFlowException, FlowNonApplicableException
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from passbook.flows.models import Flow, Stage
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from passbook.policies.engine import PolicyEngine
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LOGGER = get_logger()
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PLAN_CONTEXT_PENDING_USER = "pending_user"
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PLAN_CONTEXT_SSO = "is_sso"
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def cache_key(flow: Flow, user: Optional[User] = None) -> str:
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"""Generate Cache key for flow"""
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prefix = f"flow_{flow.pk}"
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if user:
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prefix += f"#{user.pk}"
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return prefix
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@dataclass
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class FlowPlan:
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"""This data-class is the output of a FlowPlanner. It holds a flat list
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of all Stages that should be run."""
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flow_pk: str
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stages: List[Stage] = field(default_factory=list)
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context: Dict[str, Any] = field(default_factory=dict)
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def next(self) -> Stage:
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"""Return next pending stage from the bottom of the list"""
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return self.stages[0]
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class FlowPlanner:
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"""Execute all policies to plan out a flat list of all Stages
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that should be applied."""
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use_cache: bool
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flow: Flow
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def __init__(self, flow: Flow):
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self.use_cache = True
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self.flow = flow
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def _check_flow_root_policies(self, request: HttpRequest) -> Tuple[bool, List[str]]:
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engine = PolicyEngine(self.flow.policies.all(), request.user, request)
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engine.build()
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return engine.result
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def plan(
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self, request: HttpRequest, default_context: Optional[Dict[str, Any]] = None
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) -> FlowPlan:
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"""Check each of the flows' policies, check policies for each stage with PolicyBinding
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and return ordered list"""
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LOGGER.debug("f(plan): Starting planning process", flow=self.flow)
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# First off, check the flow's direct policy bindings
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# to make sure the user even has access to the flow
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root_passing, root_passing_messages = self._check_flow_root_policies(request)
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if not root_passing:
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raise FlowNonApplicableException(root_passing_messages)
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# Bit of a workaround here, if there is a pending user set in the default context
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# we use that user for our cache key
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# to make sure they don't get the generic response
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if default_context and PLAN_CONTEXT_PENDING_USER in default_context:
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user = default_context[PLAN_CONTEXT_PENDING_USER]
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else:
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user = request.user
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cached_plan_key = cache_key(self.flow, user)
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cached_plan = cache.get(cached_plan_key, None)
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if cached_plan and self.use_cache:
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LOGGER.debug(
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"f(plan): Taking plan from cache", flow=self.flow, key=cached_plan_key
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)
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LOGGER.debug(cached_plan)
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return cached_plan
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plan = self._build_plan(user, request, default_context)
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cache.set(cache_key(self.flow, user), plan)
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if not plan.stages:
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raise EmptyFlowException()
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return plan
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def _build_plan(
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self,
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user: User,
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request: HttpRequest,
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default_context: Optional[Dict[str, Any]],
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) -> FlowPlan:
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"""Actually build flow plan"""
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start_time = time()
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plan = FlowPlan(flow_pk=self.flow.pk.hex)
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if default_context:
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plan.context = default_context
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# Check Flow policies
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for stage in (
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self.flow.stages.order_by("flowstagebinding__order")
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.select_subclasses()
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.select_related()
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):
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binding = stage.flowstagebinding_set.get(flow__pk=self.flow.pk)
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engine = PolicyEngine(binding.policies.all(), user, request)
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engine.request.context = plan.context
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engine.build()
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passing, _ = engine.result
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if passing:
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LOGGER.debug("f(plan): Stage passing", stage=stage, flow=self.flow)
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plan.stages.append(stage)
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end_time = time()
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LOGGER.debug(
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"f(plan): Finished building",
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flow=self.flow,
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duration_s=end_time - start_time,
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)
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return plan
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