Tasks (internal API)

Collection of tasks.

The debusine.tasks module hierarchy hosts a collection of BaseTask that are used by workers to fulfill debusine.db.models.WorkRequests sent by the debusine scheduler.

Creating a new task requires adding a new file containing a class inheriting from the BaseTask or RunCommandTask base class. The name of the class must be unique among all child classes.

A child class must, at the very least, override the BaseTask.execute() method.

class debusine.tasks.BaseExternalTask(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None)

Bases: BaseTask[TD, DTD], Generic[TD, DTD]

A BaseTask that runs on an external worker.

Concrete subclasses must implement:

• run(execute_directory: Path) -> bool: Do the main work of the task.

Most concrete subclasses should also implement:

• fetch_input(self, destination) -> bool. Download the needed artifacts into destination. Suggestion: can use fetch_artifact(artifact, dir) to download them. (default: return True)

• configure_for_execution(self, download_directory: Path) -> bool (default: return True)

• check_directory_for_consistency_errors(self, build_directory: Path) -> list[str] (default: return an empty list, indicating no errors)

• upload_artifacts(self, directory: Path, \*, execution_success: bool). The member variable self._source_artifacts_ids is set by fetch_input() and can be used to create the relations between uploaded artifacts and downloaded artifacts. (default: return True)

TASK_TYPE: TaskTypes = 'Worker'

The worker type must be suitable for the task type. TaskTypes.WORKER requires an external worker; TaskTypes.SERVER requires a Celery worker; TaskTypes.SIGNING requires a signing worker.

__init__(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None) → None

Initialize the task.

check_directory_for_consistency_errors(build_directory: Path) → list[str]

Return list of errors after doing the main work of the task.

cleanup() → None

Clean up after running the task.

configure_for_execution(download_directory: Path) → bool

Configure task: set variables needed for the self._cmdline().

Called after the files are downloaded via fetch_input().

configure_server_access(debusine: Debusine)

Set the object to access the server.

dynamic_task_data_type

Class used as the in-memory representation of dynamic task data.

alias of TypeVar(‘DTD’, bound=BaseDynamicTaskData)

fetch_artifact(artifact_id: int, destination: Path) → ArtifactResponse

Download artifact_id to destination.

Add artifact_id to self._source_artifacts_ids.

fetch_input(destination: Path) → bool

Download artifacts needed by the task, update self.source_artifacts_ids.

Task might use self.data.input to download the relevant artifacts.

The method self.fetch_artifact(artifact, destination) might be used to download the relevant artifacts and update self.source_artifacts_ids.

name: ClassVar[str] = 'baseexternaltask'

prepare_to_run(download_directory: Path, execute_directory: Path) → None

Prepare the execution environment to do the main work of the task.

abstract run(execute_directory: Path) → bool

Do the main work of the task.

task_data_type

Class used as the in-memory representation of task data.

alias of TypeVar(‘TD’, bound=BaseTaskData)

upload_artifacts(execute_directory: Path, *, execution_success: bool)

Upload the artifacts for the task.

class debusine.tasks.BaseTask(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None)

Bases: Generic[TD, DTD]

Base class for tasks.

A BaseTask object serves two purpose: encapsulating the logic of what needs to be done to execute the task (cf configure() and execute() that are run on a worker), and supporting the scheduler by determining if a task is suitable for a given worker. That is done in a two-step process, collating metadata from each worker (with the analyze_worker() method that is run on a worker) and then, based on this metadata, see if a task is suitable (with can_run_on() that is executed on the scheduler).

Most concrete task implementations should inherit from RunCommandTask instead.

TASK_TYPE: TaskTypes

The worker type must be suitable for the task type. TaskTypes.WORKER requires an external worker; TaskTypes.SERVER requires a Celery worker; TaskTypes.SIGNING requires a signing worker.

TASK_VERSION: int | None = None

Must be overridden by child classes to document the current version of the task’s code. A task will only be scheduled on a worker if its task version is the same as the one running on the scheduler.

__init__(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None) → None

Initialize the task.

abort()

Task does not need to be executed. Once aborted cannot be changed.

property aborted: bool

Return if the task is aborted.

Tasks cannot transition from aborted -> not-aborted.

classmethod analyze_worker() → dict[str, Any]

Return dynamic metadata about the current worker.

This method is called on the worker to collect information about the worker. The information is stored as a set of key-value pairs in a dictionary.

That information is then reused on the scheduler to be fed to can_run_on() and determine if a task is suitable to be executed on the worker.

Derived objects can extend the behaviour by overriding the method, calling metadata = super().analyze_worker(), and then adding supplementary data in the dictionary.

To avoid conflicts on the names of the keys used by different tasks you should use key names obtained with self.prefix_with_task_name(...).

Returns:

a dictionary describing the worker.

Return type:

dict.

classmethod analyze_worker_all_tasks()

Return dictionary with metadata for each task in BaseTask._sub_tasks.

Subclasses of BaseTask get registered in BaseTask._sub_tasks. Return a dictionary with the metadata of each of the subtasks.

This method is executed in the worker when submitting the dynamic metadata.

append_to_log_file(filename: str, lines: list[str]) → None

Open log file and write contents into it.

Parameters:

• filename – use self.open_debug_log_file(filename)

• lines – write contents to the logfile

can_run_on(worker_metadata: dict[str, Any]) → bool

Check if the specified worker can run the task.

This method shall take its decision solely based on the supplied worker_metadata and on the configured task data (self.data).

The default implementation always returns True unless TASK_TYPE doesn’t match the worker type or there’s a mismatch between the TASK_VERSION on the scheduler side and on the worker side.

Derived objects can implement further checks by overriding the method in the following way:

if not super().can_run_on(worker_metadata):
    return False

if ...:
    return False

return True

Parameters:

worker_metadata (dict) – The metadata collected from the worker by running analyze_worker() on all the tasks on the worker under consideration.

Returns:

the boolean result of the check.

Return type:

bool.

static class_from_name(task_type: TaskTypes, task_name: str) → type[debusine.tasks._task.BaseTask[Any, Any]]

Return class for :param task_name (case-insensitive).

Parameters:

task_type – type of task to look up

__init_subclass__() registers BaseTask subclasses’ into BaseTask._sub_tasks.

compute_dynamic_data(task_database: TaskDatabaseInterface) → Optional[DTD]

Compute dynamic data for this task.

This may involve resolving artifact lookups.

data: TD

dynamic_data: Optional[DTD]

dynamic_task_data_type: type[DTD]

Class used as the in-memory representation of dynamic task data.

execute() → bool

Call the _execute() method, upload debug artifacts.

See _execute() for more information.

Returns:

result of the _execute() method.

execute_logging_exceptions() → bool

Execute self.execute() logging any raised exceptions.

abstract get_label() → str

Return a short human-readable label for the task.

Returns:

None if no label could be computed from task data

get_source_artifacts_ids() → list[int]

Return the list of source artifact IDs used by this task.

This refers to the artifacts actually used by the task. If dynamic_data is empty, this returns the empty list.

This is used by views to show what artifacts were used by a task. _source_artifacts_ids cannot be used for this purpose because it is only set during task execution.

static is_valid_task_name(task_type: TaskTypes, task_name: str) → bool

Return True if task_name is registered (its class is imported).

static is_worker_task(task_name: str) → bool

Check if task_name is a task that can run on external workers.

logger

A logging.Logger instance that can be used in child classes when you override methods to implement the task.

name: ClassVar[str]

open_debug_log_file(filename: str, *, mode: OpenTextModeWriting = 'a') → TextIO

open_debug_log_file(filename: str, *, mode: OpenBinaryModeWriting) → BinaryIO

Open a temporary file and return it.

The files are always for the same temporary directory, calling it twice with the same file name will open the same file.

The caller must call .close() when finished writing.

classmethod prefix_with_task_name(text: str) → str

Returns:

the text prefixed with the task name and a colon.

task_data_type: type[TD]

Class used as the in-memory representation of task data.

static task_names(task_type: TaskTypes) → list[str]

Return list of sub-task names.

static worker_task_names() → list[str]

Return list of sub-task names not of type TaskTypes.SERVER.

class debusine.tasks.BaseTaskWithExecutor(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None)

Bases: BaseExternalTask[TDE, DTDE], Generic[TDE, DTDE]

Base for tasks with executor capabilities.

Concrete subclasses must implement fetch_input(), configure_for_execution(), run(), check_directory_for_consistency_errors(), and upload_artifacts(), as documented by BaseExternalTask.

DEFAULT_BACKEND = 'unshare'

property backend: str

Return the backend name to use.

cleanup() → None

Clean up after running the task.

Some tasks use the executor in upload_artifacts, so we clean up the executor here rather than in run().

dynamic_task_data_type

Class used as the in-memory representation of dynamic task data.

alias of TypeVar(‘DTDE’, bound=BaseDynamicTaskDataWithExecutor)

get_environment_lookup() → int | str | None

Get the environment lookup for an executor-capable task.

This automatically fills in some additional constraints from the task data if needed.

name: ClassVar[str] = 'basetaskwithexecutor'

prepare_to_run(download_directory: Path, execute_directory: Path) → None

Copy the download and execution directories into the executor.

task_data_type

Class used as the in-memory representation of task data.

alias of TypeVar(‘TDE’, bound=BaseTaskDataWithExecutor)

class debusine.tasks.RunCommandTask(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None)

Bases: BaseExternalTask[TD, DTD], Generic[TD, DTD]

A BaseTask that can execute commands and upload artifacts.

Concrete subclasses must implement:

• _cmdline(self) -> list[str]

• task_succeeded(self, returncode: Optional[int], execute_directory: Path) -> bool (defaults to True)

They must also implement configure_for_execution(), fetch_input(), check_directory_for_consistency_errors(), and upload_artifacts(), as documented by BaseTaskWithExecutor. (They do not need to implement run(), but may do so if they need to run multiple commands rather than just one.)

Use self.append_to_log_file() / self.open_debug_log_file() to provide information for the user (it will be available to the user as an artifact).

Command execution uses process groups to make sure that the command and possible spawned commands are finished, and cancels the execution of the command if BaseTask.aborted() is True.

See the main entry point BaseTask._execute() for details of the flow.

CAPTURE_OUTPUT_FILENAME: str | None = None

CMD_LOG_FILENAME = 'cmd-output.log'

CMD_LOG_SEPARATOR = '--------------------'

dynamic_task_data_type

Class used as the in-memory representation of dynamic task data.

alias of TypeVar(‘DTD’, bound=BaseDynamicTaskData)

name: ClassVar[str] = 'runcommandtask'

run(execute_directory) → bool

Run a single command via the executor.

Note

If the member variable CAPTURE_OUTPUT_FILENAME is set: create a file with its name with the stdout of the command. Otherwise, the stdout of the command is saved in self.CMD_LOG_FILENAME).

run_cmd(cmd: list[str], working_directory: Path, *, run_as_root: bool = False, capture_stdout_filename: str | None = None) → int | None

Run cmd in working_directory. Create self.CMD_OUTPUT_FILE log file.

If BaseTask.aborted == True terminates the process.

Parameters:

• cmd – command to execute with its arguments.

• working_directory – working directory where the command is executed.

• run_as_root – if True, run the command as root. Otherwise, the command runs as the worker’s user

• capture_stdout_filename – for some commands the output of the command is the output of stdout (e.g. lintian) and not a set of files generated by the command (e.g. sbuild). If capture_stdout is not None, save the stdout into this file. The caller can then use it.

Returns:

returncode of the process or None if aborted

task_data_type

Class used as the in-memory representation of task data.

alias of TypeVar(‘TD’, bound=BaseTaskData)

task_succeeded(returncode: int | None, execute_directory: Path) → bool

Sub-tasks can evaluate if the task was a success or failure.

By default, return True (success). Sub-classes can re-implement it.

Parameters:

• returncode – return code of the command, or None if aborted

• execute_directory – directory with the output of the task

Returns:

True (if success) or False (if failure).

exception debusine.tasks.TaskConfigError(message: str, original_exception: Exception | None = None)

Bases: Exception

Exception raised when there is an issue with a task configuration.

__init__(message: str, original_exception: Exception | None = None)

Initialize the TaskConfigError.

Parameters:

• message – human-readable message describing the error.

• original_exception – the exception that triggered this error, if applicable. This is used to provide additional information.

Task to build Debian packages with sbuild.

This task implements the PackageBuild generic task for its task_data: https://freexian-team.pages.debian.net/debusine/reference/tasks.html#task-packagebuild

class debusine.tasks.sbuild.Sbuild(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None)

Bases: SbuildValidatorMixin, RunCommandTask[SbuildData, SbuildDynamicData], BaseTaskWithExecutor[SbuildData, SbuildDynamicData]

Task implementing a Debian package build with sbuild.

TASK_VERSION: int | None = 1

Must be overridden by child classes to document the current version of the task’s code. A task will only be scheduled on a worker if its task version is the same as the one running on the scheduler.

__init__(task_data: dict[str, Any], dynamic_task_data: dict[str, Any] | None = None) → None

Initialize the sbuild task.

classmethod analyze_worker()

Report metadata for this task on this worker.

can_run_on(worker_metadata: dict[str, Any]) → bool

Check the specified worker can run the requested task.

property chroot_name: str

Build name of required chroot.

compute_dynamic_data(task_database: TaskDatabaseInterface) → SbuildDynamicData

Resolve artifact lookups for this task.

configure_for_execution(download_directory: Path) → bool

Configure Task: set variables needed for the build() step.

Return True if configuration worked, False, if there was a problem.

dynamic_task_data_type

alias of SbuildDynamicData

execute() → bool

Verify task can be executed and super().execute().

Raises:

TaskConfigError.

fetch_input(destination: Path) → bool

Download the source artifact.

get_label() → str

Return the task label.

get_source_artifacts_ids() → list[int]

Return the list of source artifact IDs used by this task.

This refers to the artifacts actually used by the task. If dynamic_data is empty, this returns the empty list.

name: ClassVar[str] = 'sbuild'

task_data_type

alias of SbuildData

upload_artifacts(directory: Path, *, execution_success: bool)

Upload the artifacts from directory.

Parameters:

• directory – directory containing the files that will be uploaded.

• execution_success – if False skip uploading .changes and .deb/.udeb