didericis
de9da29027
Review: the resolver is called rarely enough that a round-trip doesn't matter, and correctness beats speed — always fetching means a revocation, policy change, or teardown the orchestrator knows about is honored immediately instead of lingering for a cache TTL. Remove the TTL cache (and `invalidate`); `resolve` now hits the orchestrator every call. Noted in the docstring that any future caching should use orchestrator-driven invalidation, not a blind TTL. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck
76 lines
3.3 KiB
Python
76 lines
3.3 KiB
Python
"""Sidecar-side per-client policy resolver (PRD 0070).
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The consolidated sidecar serves every bottle from one process, so for each
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request it must apply the *calling* bottle's policy, selected by the source
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IP the attribution invariant makes unspoofable. This resolves that policy
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from the orchestrator's control plane (`POST /resolve`), keyed on the
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`(source_ip, identity_token)` pair.
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**Always fresh — no cache.** The resolver is called rarely enough that a
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round-trip doesn't matter, and correctness matters more than speed: every
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resolve reflects the orchestrator's *current* view, so a revocation, a
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policy change, or a bottle teardown the orchestrator knows about is honored
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immediately rather than lingering for a cache TTL. (If this ever becomes a
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hot path, add caching with orchestrator-driven invalidation — not a blind
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TTL.)
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**Fail-closed:** an unattributed client (the orchestrator answers `403`)
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resolves to `None`, and the caller (the egress addon, git-gate) must then
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deny — exactly as an unknown bottle should be treated. Orchestrator
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*errors* (unreachable / unexpected status) raise, so the caller can fail
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closed too rather than silently serving stale or empty policy.
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The resolved value is the policy blob the orchestrator stores verbatim; the
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consumer parses it (e.g. the egress addon's `load_config`). This module is
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stdlib-only and free of bot-bottle imports so it can be COPYed flat into
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the sidecar bundle.
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"""
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from __future__ import annotations
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import json
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import urllib.error
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import urllib.request
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DEFAULT_TIMEOUT_SECONDS = 2.0
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class PolicyResolveError(RuntimeError):
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"""The orchestrator was unreachable or returned an unexpected status —
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distinct from a clean `403` (unattributed), which returns None."""
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class PolicyResolver:
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"""Resolves each client's policy from the orchestrator, fresh per call."""
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def __init__(self, base_url: str, *, timeout: float = DEFAULT_TIMEOUT_SECONDS) -> None:
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self._base = base_url.rstrip("/")
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self._timeout = timeout
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def resolve(self, source_ip: str, identity_token: str) -> str | None:
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"""The calling bottle's policy blob, or None if unattributed. Always
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fetches from the orchestrator so revocations / changes / teardowns
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are honored immediately. Raises `PolicyResolveError` if the
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orchestrator can't be reached / errors."""
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body = json.dumps(
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{"source_ip": source_ip, "identity_token": identity_token}
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).encode()
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req = urllib.request.Request(
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f"{self._base}/resolve", data=body, method="POST",
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headers={"Content-Type": "application/json"},
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)
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try:
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with urllib.request.urlopen(req, timeout=self._timeout) as resp:
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payload = json.loads(resp.read())
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except urllib.error.HTTPError as e:
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if e.code == 403:
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return None # unattributed → fail closed (caller denies)
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raise PolicyResolveError(f"/resolve returned HTTP {e.code}") from e
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except (urllib.error.URLError, TimeoutError, OSError, ValueError) as e:
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raise PolicyResolveError(f"/resolve unreachable or malformed: {e}") from e
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policy = payload.get("policy") if isinstance(payload, dict) else None
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return policy if isinstance(policy, str) else ""
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__all__ = ["PolicyResolver", "PolicyResolveError"]
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