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feat: update terminal support messaging and enhance guest agent provisioning logic

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kstyagi
2026-09-25 21:12:21 +05:30
parent d870c98bfa
commit 6573f483e6
10 changed files with 163 additions and 29 deletions
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uvm/guest_exec.py
+2 -2
View File
@@ -71,8 +71,8 @@ class GuestSession:
if connection is not None:
connection.close()
raise GuestAgentUnavailableError(
"guest agent is unavailable or not ready; install it with POST /vms/{vm_id}/agent/install "
"while stopped, then start the VM (vsock-capable kernel required)"
"guest agent is unavailable or not ready; wait for guest startup, or restart the VM "
"to apply automatic vsock guest-agent setup (vsock-capable kernel required)"
) from error
def execute(self, command: str, *, sudo: bool, timeout_seconds: float) -> ExecResult:
uvm/guest_terminal.py
+2 -2
View File
@@ -38,8 +38,8 @@ class GuestTerminal(GuestSession):
except (OSError, EOFError, ProtocolError) as error:
self.close()
raise GuestAgentUnavailableError(
"Interactive terminal support is unavailable. Stop this VM, use Install / update terminal support "
"in its Sessions view, then start it and launch a new session."
"Interactive terminal support is unavailable. Restart this VM to apply automatic guest-agent setup, "
"then wait for the agent to start and launch a new session."
) from error
async def _receive_exact(self, size: int) -> bytes:
uvm/images.py
+40 -11
View File
@@ -304,10 +304,12 @@ class ImageStore:
return profile
def provision_guest_agent(self, disk: Path, vm_id: str, username: str, *, install: bool = False) -> bool:
"""Configure new templates, or explicitly install on a proven-offline disk.
"""Ensure every guest has its vsock agent before booting its private disk.
The lifecycle lock and confirmed VMM exit are required. A checked sparse
copy preserves the original disk on failure and makes retries atomic.
Return False only when the managed files and service are already current.
An explicit install request always stages and rechecks the installation.
"""
parse_username(username)
if re.fullmatch(r"[A-Za-z0-9][A-Za-z0-9_.-]{0,80}", vm_id) is None:
@@ -319,13 +321,8 @@ class ImageStore:
raise UvmError("private VM disk is unsafe for guest agent installation")
with tempfile.TemporaryDirectory(prefix="uvm-guest-agent-") as name:
files = Path(name)
if not install:
marker = self._read_guest_file(disk, "/etc/uvm-image", files / "marker",
required=False, regular_only=True)
if marker is None or marker.path.read_text(encoding="utf-8") not in {
"uvm-ubuntu-jammy-v4\n", "uvm-ubuntu-jammy-v5\n",
}:
return False
if not install and self._guest_agent_current(disk, files, vm_id, username):
return False
descriptor, candidate = tempfile.mkstemp(prefix=".rootfs-agent-", suffix=".ext4", dir=disk.parent)
os.close(descriptor)
temporary = Path(candidate)
@@ -352,16 +349,48 @@ class ImageStore:
except (OSError, UnicodeError) as error:
raise UvmError(f"could not provision guest agent: {error}") from error
@staticmethod
def _agent_payloads(vm_id: str, username: str) -> dict[str, bytes]:
payloads = guest_agent_files()
payloads["/etc/uvm-agent.json"] = (json.dumps({"vm_id": vm_id, "username": username}) + "\n").encode("utf-8")
return payloads
def _guest_agent_current(self, disk: Path, files: Path, vm_id: str, username: str) -> bool:
"""Read-only fast path; changed installations are checked again after journal replay."""
payloads = self._agent_payloads(vm_id, username)
for index, (path, content) in enumerate(payloads.items()):
existing = self._agent_file(disk, path, files / f"current-{index}")
mode = 0o600 if path.endswith(".json") else 0o644
if (existing is None or (existing.mode, existing.gid) != (mode, 0)
or existing.path.read_bytes() != content):
return False
manifest = self._agent_file(disk, "/etc/uvm-agent-files.json", files / "current-manifest")
if manifest is None or (manifest.mode, manifest.gid) != (0o600, 0):
return False
try:
hashes = json.loads(manifest.path.read_bytes())
except (ValueError, UnicodeError):
return False
if hashes != {path: hashlib.sha256(content).hexdigest() for path, content in payloads.items()}:
return False
service = self._runner.run((
"debugfs", "-R", "stat /etc/systemd/system/multi-user.target.wants/uvm-agent.service", disk,
), capture=True)
return (re.search(r"Type:\s+symlink\b", service.stdout) is not None
and 'Fast link dest: "/etc/systemd/system/uvm-agent.service"' in service.stdout)
def _install_agent_files(self, disk: Path, files: Path, vm_id: str, username: str) -> None:
for binary in ("/usr/lib/systemd/systemd", "/usr/bin/apt-get"):
result = self._runner.run(("debugfs", "-R", f"stat {binary}", disk), capture=True)
if re.search(r"Type:\s+regular\b", result.stdout) is None:
raise UvmError("guest agent installation requires a systemd/apt image (Ubuntu 22.04 or newer)")
raise UvmError(
"automatic vsock guest-agent setup requires a systemd/apt image (Ubuntu 22.04 or newer); "
"use the default Ubuntu rootfs or a compatible custom image"
)
for directory in ("/etc", "/usr", "/usr/lib", "/usr/lib/uvm", "/etc/systemd",
"/etc/systemd/system", "/etc/systemd/system/multi-user.target.wants"):
self._agent_directory(disk, directory)
payloads = guest_agent_files()
payloads["/etc/uvm-agent.json"] = (json.dumps({"vm_id": vm_id, "username": username}) + "\n").encode("utf-8")
payloads = self._agent_payloads(vm_id, username)
manifest_path = "/etc/uvm-agent-files.json"
previous = self._agent_file(disk, manifest_path, files / "manifest")
old_hashes = {}
uvm/lifecycle.py
+1
View File
@@ -198,6 +198,7 @@ class LifecycleService:
self._cleanup_runtime(vm)
self._apply_pending_resize(vm)
self._images.configure_guest_network(Path(vm.disk), vm.guest_ip)
self._images.provision_guest_agent(Path(vm.disk), vm.id, vm.username)
vm.network, vm.bridge = str(self._settings.network), self._settings.bridge
self._boot(vm, kernel)
return vm