Proven working Postgresql monitor
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Lyncoln
@@ -0,0 +1,174 @@
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#!/usr/bin/env python3
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import importlib.util
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import json
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import os
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from pathlib import Path
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class RegistryError(Exception):
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pass
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class Plugin:
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def __init__(self, plugin_root, name):
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self.name = name
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self.path = Path(plugin_root) / name
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self.manifest_path = self.path / "manifest.json"
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if not self.manifest_path.is_file():
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raise RegistryError(
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f"plugin manifest not found: {self.manifest_path}"
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)
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with self.manifest_path.open("r", encoding="utf-8") as f:
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self.manifest = json.load(f)
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module_name = self.manifest.get("module", "plugin.py")
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module_path = self.path / module_name
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if not module_path.is_file():
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raise RegistryError(
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f"plugin module not found: {module_path}"
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)
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spec = importlib.util.spec_from_file_location(
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f"managed_containerd_plugin_{name}",
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module_path,
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)
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if spec is None or spec.loader is None:
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raise RegistryError(
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f"unable to load plugin: {name}"
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)
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self.module = importlib.util.module_from_spec(spec)
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spec.loader.exec_module(self.module)
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@property
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def actions(self):
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return list(self.manifest.get("actions", []))
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@property
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def required_config(self):
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return list(
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self.manifest.get("required_config", [])
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)
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def validate_config(self, config):
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missing = [
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key
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for key in self.required_config
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if not config.get(key)
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]
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if missing:
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raise RegistryError(
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"missing required configuration: "
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+ ", ".join(missing)
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)
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def execute(self, action, config):
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if action not in self.actions:
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raise RegistryError(
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f"plugin {self.name} does not support action {action}"
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)
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handler = getattr(self.module, action, None)
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if handler is None:
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raise RegistryError(
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f"plugin {self.name} advertises {action} "
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"but does not implement it"
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)
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return handler(config)
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class Resource:
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def __init__(self, resource_id, plugin, config):
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self.resource_id = resource_id
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self.plugin = plugin
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self.config = config
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self.plugin.validate_config(config)
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def describe(self):
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return {
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"resource": self.resource_id,
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"plugin": self.plugin.name,
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"plugin_version": self.plugin.manifest.get(
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"version"
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),
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"actions": self.plugin.actions,
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"configured": True,
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}
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class Registry:
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def __init__(self):
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self.plugin_root = os.environ.get(
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"MANAGED_CONTAINERD_PLUGIN_ROOT",
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"/opt/managed-containerd/plugins",
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)
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self.resources = {}
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self._load_environment_resource()
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def _load_environment_resource(self):
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resource_id = os.environ.get("RESOURCE_ID")
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plugin_name = os.environ.get("PLUGIN")
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if not resource_id:
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raise RegistryError(
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"RESOURCE_ID is not configured"
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)
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if not plugin_name:
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raise RegistryError(
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"PLUGIN is not configured"
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)
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plugin = Plugin(
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self.plugin_root,
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plugin_name,
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)
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config = {
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key: os.environ.get(key)
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for key in plugin.required_config
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}
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self.resources[resource_id] = Resource(
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resource_id,
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plugin,
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config,
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)
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def list_resources(self):
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return {
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resource_id: resource.describe()
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for resource_id, resource
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in self.resources.items()
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}
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def execute(self, resource_id, action):
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resource = self.resources.get(resource_id)
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if resource is None:
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raise RegistryError(
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f"unknown resource: {resource_id}"
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)
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result = resource.plugin.execute(
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action,
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resource.config,
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)
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return {
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"ok": True,
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"resource": resource_id,
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"plugin": resource.plugin.name,
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"action": action,
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"result": result,
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}
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@@ -0,0 +1,165 @@
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#!/usr/bin/env python3
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import json
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import os
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import signal
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import socket
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import traceback
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from registry import Registry, RegistryError
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SOCKET_PATH = os.environ.get(
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"MANAGED_CONTAINERD_SOCKET",
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"/run/managed-containerd/managed-containerd.sock",
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)
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server_socket = None
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registry = None
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def handle_request(req):
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action = req.get("action")
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if action == "ping":
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return {
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"ok": True,
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"daemon": "managed-containerd",
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"protocol_version": 1,
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}
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if action == "registry.list":
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return {
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"ok": True,
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"resources": registry.list_resources(),
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}
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resource = req.get("resource")
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if not resource:
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return {
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"ok": False,
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"error": "resource is required",
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}
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return registry.execute(
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resource,
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action,
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)
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def cleanup_socket():
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try:
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os.unlink(SOCKET_PATH)
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except FileNotFoundError:
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pass
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def shutdown(signum, frame):
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global server_socket
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print(
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f"managed-containerd received signal {signum}; shutting down",
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flush=True,
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)
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if server_socket is not None:
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try:
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server_socket.close()
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except OSError:
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pass
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cleanup_socket()
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raise SystemExit(0)
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def serve():
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global server_socket
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global registry
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registry = Registry()
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os.makedirs(
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os.path.dirname(SOCKET_PATH),
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exist_ok=True,
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)
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cleanup_socket()
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signal.signal(signal.SIGTERM, shutdown)
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signal.signal(signal.SIGINT, shutdown)
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server_socket = socket.socket(
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socket.AF_UNIX,
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socket.SOCK_STREAM,
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)
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server_socket.bind(SOCKET_PATH)
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os.chmod(SOCKET_PATH, 0o660)
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server_socket.listen(16)
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print(
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f"managed-containerd listening on {SOCKET_PATH}",
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flush=True,
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)
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print(
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"registered resources: "
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+ ", ".join(registry.resources),
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flush=True,
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)
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try:
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while True:
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conn, _ = server_socket.accept()
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with conn:
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try:
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raw = b""
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while b"\n" not in raw:
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chunk = conn.recv(65536)
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if not chunk:
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break
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raw += chunk
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req = json.loads(
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raw.decode("utf-8").strip()
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)
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response = handle_request(req)
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except (
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RegistryError,
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ValueError,
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KeyError,
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) as exc:
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response = {
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"ok": False,
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"error": str(exc),
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}
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except Exception as exc:
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traceback.print_exc()
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response = {
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"ok": False,
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"error": str(exc),
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}
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conn.sendall(
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json.dumps(
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response,
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default=str,
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).encode("utf-8")
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+ b"\n"
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)
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finally:
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cleanup_socket()
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if __name__ == "__main__":
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serve()
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