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https://github.com/kevinveenbirkenbach/computer-playbook.git
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37 lines
898 B
Python
37 lines
898 B
Python
from __future__ import annotations
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import json
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import os
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from pathlib import Path
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from typing import Mapping
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DOCKER_DAEMON_CONFIG_PATH = Path("/etc/docker/daemon.json")
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MIN_VALID_MTU = 576
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MAX_VALID_MTU = 9000
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def detect_outer_network_mtu(
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env: Mapping[str, str] | None = None,
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*,
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daemon_config_path: Path = DOCKER_DAEMON_CONFIG_PATH,
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) -> str | None:
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current_env = os.environ if env is None else env
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explicit_mtu = current_env.get("INFINITO_OUTER_NETWORK_MTU", "").strip()
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if explicit_mtu:
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return explicit_mtu
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if not daemon_config_path.exists():
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return None
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try:
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daemon_config = json.loads(daemon_config_path.read_text())
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except (json.JSONDecodeError, OSError):
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return None
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mtu = daemon_config.get("mtu")
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if isinstance(mtu, int) and MIN_VALID_MTU <= mtu <= MAX_VALID_MTU:
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return str(mtu)
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return None
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