selfprivacy-rest-api/selfprivacy_api/services/service.py

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"""Abstract class for a service running on a server"""
from abc import ABC, abstractmethod
from typing import List, Optional
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from selfprivacy_api import utils
from selfprivacy_api.utils.default_subdomains import DEFAULT_SUBDOMAINS
from selfprivacy_api.utils import ReadUserData, WriteUserData, get_domain
from selfprivacy_api.utils.waitloop import wait_until_true
from selfprivacy_api.utils.block_devices import BlockDevice, BlockDevices
from selfprivacy_api.jobs import Job, Jobs, JobStatus, report_progress
from selfprivacy_api.jobs.upgrade_system import rebuild_system
from selfprivacy_api.models.services import ServiceStatus, ServiceDnsRecord
from selfprivacy_api.services.generic_size_counter import get_storage_usage
from selfprivacy_api.services.owned_path import OwnedPath, Bind
from selfprivacy_api.services.moving import (
check_binds,
check_volume,
unbind_folders,
bind_folders,
ensure_folder_ownership,
MoveError,
move_data_to_volume,
)
DEFAULT_START_STOP_TIMEOUT = 5 * 60
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class Service(ABC):
"""
Service here is some software that is hosted on the server and
can be installed, configured and used by a user.
"""
@staticmethod
@abstractmethod
def get_id() -> str:
"""
The unique id of the service.
"""
pass
@staticmethod
@abstractmethod
def get_display_name() -> str:
"""
The name of the service that is shown to the user.
"""
pass
@staticmethod
@abstractmethod
def get_description() -> str:
"""
The description of the service that is shown to the user.
"""
pass
@staticmethod
@abstractmethod
def get_svg_icon() -> str:
"""
The monochrome svg icon of the service.
"""
pass
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@classmethod
def get_url(cls) -> Optional[str]:
"""
The url of the service if it is accessible from the internet browser.
"""
domain = get_domain()
subdomain = cls.get_subdomain()
return f"https://{subdomain}.{domain}"
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@classmethod
def get_subdomain(cls) -> Optional[str]:
"""
The assigned primary subdomain for this service.
"""
name = cls.get_id()
with ReadUserData() as user_data:
if "modules" in user_data:
if name in user_data["modules"]:
if "subdomain" in user_data["modules"][name]:
return user_data["modules"][name]["subdomain"]
return DEFAULT_SUBDOMAINS.get(name)
@classmethod
def get_user(cls) -> Optional[str]:
"""
The user that owns the service's files.
Defaults to the service's id.
"""
return cls.get_id()
@classmethod
def get_group(cls) -> Optional[str]:
"""
The group that owns the service's files.
Defaults to the service's user.
"""
return cls.get_user()
@staticmethod
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@abstractmethod
def is_movable() -> bool:
"""`True` if the service can be moved to the non-system volume."""
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pass
@staticmethod
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@abstractmethod
def is_required() -> bool:
"""`True` if the service is required for the server to function."""
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pass
@staticmethod
def can_be_backed_up() -> bool:
"""`True` if the service can be backed up."""
return True
@staticmethod
@abstractmethod
def get_backup_description() -> str:
"""
The text shown to the user that exlplains what data will be
backed up.
"""
pass
@classmethod
def is_enabled(cls) -> bool:
"""
`True` if the service is enabled.
`False` if it is not enabled or not defined in file
If there is nothing in the file, this is equivalent to False
because NixOS won't enable it then.
"""
name = cls.get_id()
with ReadUserData() as user_data:
return user_data.get("modules", {}).get(name, {}).get("enable", False)
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@staticmethod
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@abstractmethod
def get_status() -> ServiceStatus:
"""The status of the service, reported by systemd."""
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pass
@classmethod
def _set_enable(cls, enable: bool):
name = cls.get_id()
with WriteUserData() as user_data:
if "modules" not in user_data:
user_data["modules"] = {}
if name not in user_data["modules"]:
user_data["modules"][name] = {}
user_data["modules"][name]["enable"] = enable
@classmethod
def enable(cls):
"""Enable the service. Usually this means enabling systemd unit."""
cls._set_enable(True)
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@classmethod
def disable(cls):
"""Disable the service. Usually this means disabling systemd unit."""
cls._set_enable(False)
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@staticmethod
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@abstractmethod
def stop():
"""Stop the service. Usually this means stopping systemd unit."""
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pass
@staticmethod
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@abstractmethod
def start():
"""Start the service. Usually this means starting systemd unit."""
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pass
@staticmethod
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@abstractmethod
def restart():
"""Restart the service. Usually this means restarting systemd unit."""
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pass
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@classmethod
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@abstractmethod
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def get_configuration(cls) -> dict:
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pass
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@classmethod
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@abstractmethod
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def set_configuration(cls, config_items):
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pass
@staticmethod
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@abstractmethod
def get_logs():
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pass
@classmethod
def get_storage_usage(cls) -> int:
"""
Calculate the real storage usage of folders occupied by service
Calculate using pathlib.
Do not follow symlinks.
"""
storage_used = 0
for folder in cls.get_folders():
storage_used += get_storage_usage(folder)
return storage_used
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@classmethod
def get_dns_records(cls, ip4: str, ip6: Optional[str]) -> List[ServiceDnsRecord]:
subdomain = cls.get_subdomain()
display_name = cls.get_display_name()
if subdomain is None:
return []
dns_records = [
ServiceDnsRecord(
type="A",
name=subdomain,
content=ip4,
ttl=3600,
display_name=display_name,
)
]
if ip6 is not None:
dns_records.append(
ServiceDnsRecord(
type="AAAA",
name=subdomain,
content=ip6,
ttl=3600,
display_name=f"{display_name} (IPv6)",
)
)
return dns_records
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@classmethod
def get_drive(cls) -> str:
"""
Get the name of the drive/volume where the service is located.
Example values are `sda1`, `vda`, `sdb`.
"""
root_device: str = BlockDevices().get_root_block_device().name
if not cls.is_movable():
return root_device
with utils.ReadUserData() as userdata:
if userdata.get("useBinds", False):
return (
userdata.get("modules", {})
.get(cls.get_id(), {})
.get(
"location",
root_device,
)
)
else:
return root_device
@classmethod
def get_folders(cls) -> List[str]:
"""
get a plain list of occupied directories
Default extracts info from overriden get_owned_folders()
"""
if cls.get_owned_folders == Service.get_owned_folders:
raise NotImplementedError(
"you need to implement at least one of get_folders() or get_owned_folders()"
)
return [owned_folder.path for owned_folder in cls.get_owned_folders()]
@classmethod
def get_owned_folders(cls) -> List[OwnedPath]:
"""
Get a list of occupied directories with ownership info
Default extracts info from overriden get_folders()
"""
if cls.get_folders == Service.get_folders:
raise NotImplementedError(
"you need to implement at least one of get_folders() or get_owned_folders()"
)
return [cls.owned_path(path) for path in cls.get_folders()]
@staticmethod
def get_foldername(path: str) -> str:
return path.split("/")[-1]
# TODO: with better json utils, it can be one line, and not a separate function
@classmethod
def set_location(cls, volume: BlockDevice):
"""
Only changes userdata
"""
service_id = cls.get_id()
with WriteUserData() as user_data:
if "modules" not in user_data:
user_data["modules"] = {}
if service_id not in user_data["modules"]:
user_data["modules"][service_id] = {}
user_data["modules"][service_id]["location"] = volume.name
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def binds(self) -> List[Bind]:
owned_folders = self.get_owned_folders()
return [
Bind.from_owned_path(folder, self.get_drive()) for folder in owned_folders
]
def assert_can_move(self, new_volume):
"""
Checks if the service can be moved to new volume
Raises errors if it cannot
"""
service_name = self.get_display_name()
if not self.is_movable():
raise MoveError(f"{service_name} is not movable")
with ReadUserData() as user_data:
if not user_data.get("useBinds", False):
raise MoveError("Server is not using binds.")
current_volume_name = self.get_drive()
if current_volume_name == new_volume.name:
raise MoveError(f"{service_name} is already on volume {new_volume}")
check_volume(new_volume, space_needed=self.get_storage_usage())
binds = self.binds()
if binds == []:
raise MoveError("nothing to move")
check_binds(current_volume_name, binds)
def do_move_to_volume(
self,
new_volume: BlockDevice,
job: Job,
):
"""
Move a service to another volume.
Note: It may be much simpler to write it per bind, but a bit less safe?
"""
service_name = self.get_display_name()
binds = self.binds()
report_progress(10, job, "Unmounting folders from old volume...")
unbind_folders(binds)
report_progress(20, job, "Moving data to new volume...")
binds = move_data_to_volume(binds, new_volume, job)
report_progress(70, job, f"Making sure {service_name} owns its files...")
try:
ensure_folder_ownership(binds)
except Exception as error:
# We have logged it via print and we additionally log it here in the error field
# We are continuing anyway but Job has no warning field
Jobs.update(
job,
JobStatus.RUNNING,
error=f"Service {service_name} will not be able to write files: "
+ str(error),
)
report_progress(90, job, f"Mounting {service_name} data...")
bind_folders(binds)
report_progress(95, job, f"Finishing moving {service_name}...")
self.set_location(new_volume)
def move_to_volume(self, volume: BlockDevice, job: Job) -> Job:
service_name = self.get_display_name()
report_progress(0, job, "Performing pre-move checks...")
self.assert_can_move(volume)
report_progress(5, job, f"Stopping {service_name}...")
assert self is not None
with StoppedService(self):
report_progress(9, job, "Stopped service, starting the move...")
self.do_move_to_volume(volume, job)
report_progress(98, job, "Move complete, rebuilding...")
rebuild_system(job, upgrade=False)
Jobs.update(
job=job,
status=JobStatus.FINISHED,
result=f"{service_name} moved successfully.",
status_text=f"Starting {service_name}...",
progress=100,
)
return job
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@classmethod
def owned_path(cls, path: str):
"""Default folder ownership"""
service_name = cls.get_display_name()
try:
owner = cls.get_user()
if owner is None:
# TODO: assume root?
# (if we do not want to do assumptions, maybe not declare user optional?)
raise LookupError(f"no user for service: {service_name}")
group = cls.get_group()
if group is None:
raise LookupError(f"no group for service: {service_name}")
except Exception as error:
raise LookupError(
f"when deciding a bind for folder {path} of service {service_name}, error: {str(error)}"
)
return OwnedPath(
path=path,
owner=owner,
group=group,
)
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def pre_backup(self):
pass
def post_restore(self):
pass
class StoppedService:
"""
A context manager that stops the service if needed and reactivates it
after you are done if it was active
Example:
```
assert service.get_status() == ServiceStatus.ACTIVE
with StoppedService(service) [as stopped_service]:
assert service.get_status() == ServiceStatus.INACTIVE
```
"""
def __init__(self, service: Service):
self.service = service
self.original_status = service.get_status()
def __enter__(self) -> Service:
self.original_status = self.service.get_status()
if self.original_status not in [ServiceStatus.INACTIVE, ServiceStatus.FAILED]:
try:
self.service.stop()
wait_until_true(
lambda: self.service.get_status() == ServiceStatus.INACTIVE,
timeout_sec=DEFAULT_START_STOP_TIMEOUT,
)
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except TimeoutError as error:
raise TimeoutError(
f"timed out waiting for {self.service.get_display_name()} to stop"
) from error
return self.service
def __exit__(self, type, value, traceback):
if self.original_status in [ServiceStatus.ACTIVATING, ServiceStatus.ACTIVE]:
try:
self.service.start()
wait_until_true(
lambda: self.service.get_status() == ServiceStatus.ACTIVE,
timeout_sec=DEFAULT_START_STOP_TIMEOUT,
)
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except TimeoutError as error:
raise TimeoutError(
f"timed out waiting for {self.service.get_display_name()} to start"
) from error