didericis
40ad2364ab
Deterministic per-bottle address assignment on the consolidated docker gateway's shared network — the address the gateway uses as its attribution key. Pure ipaddress logic; the docker-specific inputs (subnet CIDR, the gateway container's own address) are gathered by the caller and passed as `taken`, keeping it testable without docker. - next_free_ip(cidr, taken): lowest host address not reserved (network + broadcast excluded by hosts(); docker's router .1 excluded here) and not already assigned (gateway container + live bottles from the registry). NoFreeAddressError when the subnet is exhausted. pyright 0 errors; pylint 9.83/10; unit suite green (the 13 test_sidecar_init /bin/sleep errors are pre-existing NixOS-local noise). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WBMWTEtQdJ4W5UrWuLHCck
48 lines
1.9 KiB
Python
48 lines
1.9 KiB
Python
"""Shared-gateway source-IP allocation for the consolidated docker backend
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(PRD 0070).
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In the consolidated model one gateway container serves every bottle over a
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single shared docker network, and each agent bottle attaches with a pinned,
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deterministic address that the gateway uses as its **attribution key**. This
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allocates those addresses from the network's subnet, skipping the reserved
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ones — the network address and broadcast (excluded by `hosts()`), docker's
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router `.1`, and everything already in use (`taken`: the gateway container
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plus every live bottle, which the caller reads from the registry).
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Pure `ipaddress` logic — the docker-specific bits (the subnet CIDR, the
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gateway container's own address) are gathered by the caller and passed in, so
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this stays testable without docker.
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"""
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from __future__ import annotations
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import ipaddress
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from collections.abc import Iterable
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class NoFreeAddressError(RuntimeError):
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"""The shared gateway network's subnet is exhausted — every host address
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is reserved or already assigned to a bottle."""
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def next_free_ip(cidr: str, taken: Iterable[str]) -> str:
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"""The lowest host address in `cidr` not in `taken` and not docker's
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router (`.1`). `taken` must include the gateway container's own address
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and every live bottle's. Raises `NoFreeAddressError` if the subnet is
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full."""
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net = ipaddress.ip_network(cidr, strict=False)
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reserved = {str(a) for a in taken}
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# Docker assigns the network's first host (.1) to the bridge router; a
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# bottle must never be handed that address.
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reserved.add(str(net.network_address + 1))
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for host in net.hosts(): # hosts() already excludes network + broadcast
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candidate = str(host)
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if candidate not in reserved:
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return candidate
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raise NoFreeAddressError(
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f"no free address in {cidr} ({len(reserved)} reserved/assigned)"
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)
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__all__ = ["next_free_ip", "NoFreeAddressError"]
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