Initial commit: stateful OpenStack API laboratory simulator.

Ship Keystone auth, multi-service handlers (Yoga→Dalmatian), Compose/Helm
packaging, API contract packs, and pytest/Pulumi coverage labs.

app/simulation/scenarios.py

@@ -0,0 +1,49 @@
+"""Seeded deterministic fault-rule evaluation."""
+
+from __future__ import annotations
+
+import hashlib
+from dataclasses import dataclass
+
+
+@dataclass(frozen=True, slots=True)
+class FaultContext:
+    method: str
+    path: str
+    principal: str | None = None
+    node: str | None = None
+    vmid: str | None = None
+    call_number: int = 1
+
+
+@dataclass(frozen=True, slots=True)
+class FaultRule:
+    kind: str
+    probability: float = 1.0
+    method: str | None = None
+    path_prefix: str | None = None
+    principal: str | None = None
+    node: str | None = None
+    vmid: str | None = None
+    call_number: int | None = None
+
+    def __post_init__(self) -> None:
+        if not 0 <= self.probability <= 1:
+            raise ValueError("fault probability must be between zero and one")
+
+
+def matches(rule: FaultRule, context: FaultContext, seed: int) -> bool:
+    filters = (
+        (rule.method, context.method),
+        (rule.principal, context.principal),
+        (rule.node, context.node),
+        (rule.vmid, context.vmid),
+        (rule.call_number, context.call_number),
+    )
+    if any(expected is not None and expected != actual for expected, actual in filters):
+        return False
+    if rule.path_prefix is not None and not context.path.startswith(rule.path_prefix):
+        return False
+    material = f"{seed}:{rule.kind}:{context.method}:{context.path}:{context.call_number}"
+    sample = int.from_bytes(hashlib.sha256(material.encode()).digest()[:8], "big") / 2**64
+    return sample < rule.probability