kstyagi
b0bf99a6ee
- Introduced a standalone guest execution agent to facilitate command execution within the guest VM over Firecracker's vsock. - Enhanced FirecrackerClient to support vsock configuration, validating guest CID and UDS path. - Updated configuration to include vsock settings by default. - Refactored FirecrackerProcessManager to manage runtime sockets more effectively. - Implemented guest agent installation and provisioning in the image store. - Added API endpoints for executing commands in the VM and installing the guest agent. - Improved error handling for guest execution failures and agent availability.
200 lines
11 KiB
Python
200 lines
11 KiB
Python
from __future__ import annotations
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import hashlib
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import json
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import shutil
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import sys
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import tempfile
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import unittest
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from pathlib import Path
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from unittest.mock import patch
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from uvm.config import Settings
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from uvm.errors import UvmError
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from uvm.images import GUEST_AGENT_PREPARE, ImageStore, guest_agent_files
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from uvm.system import CommandRunner
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class GuestRuntimeBootstrapTests(unittest.TestCase):
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def test_runtime_install_is_guest_only_skipped_when_ready_and_stops_on_apt_failure(self) -> None:
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with tempfile.TemporaryDirectory() as temporary:
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directory = Path(temporary)
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python = directory / "python3"
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apt = directory / "apt-get"
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ready = directory / "ready"
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python.write_text(
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f"#!{sys.executable}\nimport os, sys\nfrom pathlib import Path\n"
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"sys.exit(0 if Path(os.environ['READY']).exists() else 1)\n", encoding="utf-8",
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)
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apt.write_text(
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f"#!{sys.executable}\nimport json, os, sys\nfrom pathlib import Path\n"
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"print(json.dumps(sys.argv[1:]))\n"
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"if sys.argv[-1] == 'update' and os.environ['FAIL_UPDATE'] == '1': sys.exit(100)\n"
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"if sys.argv[-1] == 'python3': Path(os.environ['READY']).touch()\n", encoding="utf-8",
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)
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python.chmod(0o755)
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apt.chmod(0o755)
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script = GUEST_AGENT_PREPARE.replace("/usr/bin/python3", str(python)).replace("/usr/bin/apt-get", str(apt))
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for installed, fail in ((True, False), (False, False), (False, True)):
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with self.subTest(installed=installed, fail=fail):
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ready.unlink(missing_ok=True)
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if installed:
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ready.touch()
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result = CommandRunner(emit=None).run((
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"env", f"READY={ready}", f"FAIL_UPDATE={int(fail)}", "/bin/sh", "-c", script,
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), check=False, capture=True)
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calls = [json.loads(line) for line in result.stdout.splitlines()]
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self.assertEqual(result.returncode, 100 if fail else 0)
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self.assertEqual(len(calls), 0 if installed else 1 if fail else 2)
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if calls:
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self.assertEqual(calls[0][-1], "update")
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self.assertIn("APT::Update::Error-Mode=any", calls[0])
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if not installed and not fail:
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self.assertEqual(calls[-1][-2:], ["install", "python3"])
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@unittest.skipUnless(all(shutil.which(tool) for tool in ("mkfs.ext4", "debugfs", "e2fsck", "cp")),
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"e2fsprogs and coreutils are required for offline guest agent checks")
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class GuestAgentImageTests(unittest.TestCase):
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def setUp(self) -> None:
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temporary = tempfile.TemporaryDirectory()
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self.addCleanup(temporary.cleanup)
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self.base = Path(temporary.name)
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self.settings = Settings(base=self.base / "uvm")
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self.settings.images_dir.mkdir(parents=True)
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self.disk = self.base / "VM with spaces" / "rootfs.ext4"
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self.disk.parent.mkdir()
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self.runner = CommandRunner(emit=None)
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self.images = ImageStore(self.settings, self.runner)
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self.retained = {
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"/etc/shadow": "worker:$6$retained-hash:1:0:99999:7:::\n",
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"/etc/ssh/ssh_host_ed25519_key": "retained private SSH key\n",
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"/home/worker/data": "retained application data\n",
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}
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def make_disk(self, marker="uvm-ubuntu-jammy-v3\n") -> None:
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root = self.base / "tree"
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payloads = {
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**self.retained, "/etc/uvm-image": marker,
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"/usr/lib/systemd/systemd": "systemd fixture", "/usr/bin/apt-get": "apt fixture",
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}
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for path, content in payloads.items():
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target = root / path.lstrip("/")
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target.parent.mkdir(parents=True, exist_ok=True)
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target.write_text(content, encoding="utf-8")
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target.chmod(0o644)
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for directory in (root, *(path for path in root.rglob("*") if path.is_dir())):
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directory.chmod(0o755)
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with self.settings.rootfs_image.open("wb") as image:
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image.truncate(32 * 1024 * 1024)
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self.runner.run(("mkfs.ext4", "-q", "-F", "-b", "4096", "-d", root, self.settings.rootfs_image), capture=True)
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# mkfs -d retains the creating user's ownership. Model the root-built
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# guest while allowing this test itself to run without root.
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paths = {"/"}
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for path in payloads:
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paths.add(path)
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paths.update(str(parent) for parent in Path(path).parents)
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commands = "\n".join(f"set_inode_field {path} {field} 0" for path in paths for field in ("uid", "gid"))
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self.runner.run(("debugfs", "-w", self.settings.rootfs_image), input_text=commands + "\n", capture=True)
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self.runner.run(("cp", "--sparse=always", self.settings.rootfs_image, self.disk), capture=True)
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self.disk.chmod(0o600)
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def guest(self, command: str, *, disk: Path | None = None) -> str:
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return self.runner.run(("debugfs", "-R", command, disk or self.disk), capture=True).stdout
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def snapshot(self) -> tuple[int, bytes]:
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return self.disk.stat().st_ino, hashlib.sha256(self.disk.read_bytes()).digest()
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def replace_guest_file(self, path: str, contents: str, *, disk: Path | None = None) -> None:
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source = self.base / "edited"
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source.write_text(contents, encoding="utf-8")
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source.chmod(0o644)
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self.runner.run(("debugfs", "-w", disk or self.disk), input_text=(
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f"rm {path}\nwrite {source} {path}\nset_inode_field {path} uid 0\nset_inode_field {path} gid 0\n"
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), capture=True)
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def test_existing_guest_is_upgraded_atomically_with_private_identity_and_retained_data(self) -> None:
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self.make_disk()
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template = hashlib.sha256(self.settings.rootfs_image.read_bytes()).digest()
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self.assertTrue(self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True))
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self.assertEqual(json.loads(self.guest("cat /etc/uvm-agent.json")), {"vm_id": "vm-test", "username": "worker"})
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self.assertRegex(self.guest("stat /etc/uvm-agent.json"), r"Mode:\s+0?600")
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self.assertRegex(self.guest("stat /etc/uvm-agent.json"), r"User:\s+0\s+Group:\s+0")
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for path, content in guest_agent_files().items():
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self.assertEqual(self.guest(f"cat {path}"), content.decode("utf-8"))
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self.assertIn('Fast link dest: "/etc/systemd/system/uvm-agent.service"',
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self.guest("stat /etc/systemd/system/multi-user.target.wants/uvm-agent.service"))
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self.assertEqual(self.guest("cat /etc/uvm-image"), "uvm-ubuntu-jammy-v3\n")
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for path, content in self.retained.items():
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self.assertEqual(self.guest(f"cat {path}"), content)
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self.assertEqual(hashlib.sha256(self.settings.rootfs_image.read_bytes()).digest(), template)
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self.assertEqual(self.disk.stat().st_mode & 0o777, 0o600)
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self.runner.run(("e2fsck", "-f", "-n", self.disk), capture=True)
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self.assertEqual(list(self.disk.parent.iterdir()), [self.disk])
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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self.assertEqual(self.guest("cat /home/worker/data"), self.retained["/home/worker/data"])
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def test_current_templates_are_configured_and_older_templates_require_explicit_install(self) -> None:
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self.make_disk()
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before = self.snapshot()
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self.assertFalse(self.images.provision_guest_agent(self.disk, "vm-test", "worker"))
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self.assertEqual(self.snapshot(), before)
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self.replace_guest_file("/etc/uvm-image", "uvm-ubuntu-jammy-v4\n")
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self.assertTrue(self.images.provision_guest_agent(self.disk, "vm-test", "worker"))
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def test_agent_updates_use_recorded_hashes_but_preserve_guest_customizations(self) -> None:
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self.make_disk()
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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updated = guest_agent_files()
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updated["/usr/lib/uvm/agent.py"] += b"\n# next packaged revision\n"
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with patch("uvm.images.guest_agent_files", return_value=updated):
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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self.assertTrue(self.guest("cat /usr/lib/uvm/agent.py").endswith("# next packaged revision\n"))
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self.replace_guest_file("/usr/lib/uvm/agent.py", "guest customization\n")
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before = self.snapshot()
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with self.assertRaisesRegex(UvmError, "customized guest agent file"):
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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self.assertEqual(self.snapshot(), before)
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self.assertEqual(list(self.disk.parent.iterdir()), [self.disk])
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def test_failure_during_provisioning_keeps_the_original_disk(self) -> None:
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self.make_disk()
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before = self.snapshot()
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write = self.images._write_guest_file
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def fail(candidate, path, source):
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self.assertNotEqual(candidate, self.disk)
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write(candidate, path, source)
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raise UvmError("simulated write failure")
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with patch.object(self.images, "_write_guest_file", side_effect=fail), self.assertRaisesRegex(UvmError, "write failure"):
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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self.assertEqual(self.snapshot(), before)
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self.assertEqual(list(self.disk.parent.iterdir()), [self.disk])
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def test_guest_edits_revealed_by_journal_replay_are_checked_before_replacement(self) -> None:
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self.make_disk()
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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before = self.snapshot()
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run = self.runner.run
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def replay(command, **options):
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result = run(command, **options)
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if command[:3] == ("e2fsck", "-f", "-p"):
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self.replace_guest_file("/usr/lib/uvm/agent.py", "journal-committed guest edit\n", disk=command[-1])
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return result
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with patch.object(self.runner, "run", side_effect=replay), self.assertRaisesRegex(UvmError, "customized"):
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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self.assertEqual(self.snapshot(), before)
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def test_unsafe_guest_directory_and_shared_disk_are_rejected(self) -> None:
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self.make_disk()
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with self.assertRaisesRegex(UvmError, "unsafe"):
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self.images.provision_guest_agent(self.settings.rootfs_image, "vm-test", "worker", install=True)
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self.runner.run(("debugfs", "-w", "-R", "set_inode_field /etc mode 040777", self.disk), capture=True)
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before = self.snapshot()
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with self.assertRaisesRegex(UvmError, "unsafe guest agent directory"):
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self.images.provision_guest_agent(self.disk, "vm-test", "worker", install=True)
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self.assertEqual(self.snapshot(), before)
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