openjd-sessions 0.8.1

Provides a library that can be used to build a runtime that is able to run Jobs in a Session as defined by Open Job Description.

Open Job Description - Sessions for Python

Open Job Description is a flexible open specification for defining render jobs which are portable between studios and render solutions. This package provides a library that can be used to build a runtime that is able to run Jobs in a Session as defined by Open Job Description.

For more information about Open Job Description and our goals with it, please see the Open Job Description Wiki on GitHub.

Compatibility

This library requires:

1. Python 3.9 or higher;
2. Linux, MacOS, or Windows operating system;
3. On Linux/MacOS:
   • sudo
4. On Windows:
   • CPython implementation of Python

Versioning

This package's version follows Semantic Versioning 2.0, but is still considered to be in its initial development, thus backwards incompatible versions are denoted by minor version bumps. To help illustrate how versions will increment during this initial development stage, they are described below:

1. The MAJOR version is currently 0, indicating initial development.
2. The MINOR version is currently incremented when backwards incompatible changes are introduced to the public API.
3. The PATCH version is currently incremented when bug fixes or backwards compatible changes are introduced to the public API.

Contributing

We encourage all contributions to this package. Whether it's a bug report, new feature, correction, or additional documentation, we greatly value feedback and contributions from our community.

Please see CONTRIBUTING.md for our contributing guidelines.

Example Usage

Running a Session

from openjd.model import (
    StepParameterSpaceIterator,
    create_job,
    decode_job_template,
    preprocess_job_parameters
)
from openjd.sessions import (
    LOG,
    ActionState,
    ActionStatus,
    Session
)
import logging
import os
from pathlib import Path
import sys
from threading import Event

#   Setup
# ========
job_template_path = Path("/absolute/path/to/job")
job_template = decode_job_template(
    template={
        "name": "DemoJob",
        "specificationVersion": "jobtemplate-2023-09",
        "parameterDefinitions": [
            { "name": "Foo", "type": "INT" }
        ],
        "jobEnvironments": [
            {
                "name": "DemoJobEnv",
                "script": {
                    "actions": {
                        "onEnter": { "command": "python", "args": [ "-c", "print('Entering DemoJobEnv')" ] },
                        "onExit": { "command": "python", "args": [ "-c", "print('Exiting DemoJobEnv')" ] }
                    }
                }
            }
        ],
        "steps": [
            {
                "name": "DemoStep",
                "stepEnvironments": [
                    {
                        "name": "DemoStepEnv",
                        "script": {
                            "actions": {
                        "onEnter": { "command": "python", "args": [ "-c", "print('Entering DemoStepEnv')" ] },
                        "onExit": { "command": "python", "args": [ "-c", "print('Exiting DemoStepEnv')" ] }
                    }
                        }
                    }
                ],
                "parameterSpace": {
                    "taskParameterDefinitions": [
                        { "name": "Bar", "type": "INT", "range": "1-10" }
                    ]
                },
                "script": {
                    "actions": {
                        "onRun": { "command": "python", "args": [ "-c", "print(r'Foo={{Param.Foo}} Bar={{Task.Param.Bar}}')" ] }
                    }
                }
            }
        ]
    }
)
job_parameters = preprocess_job_parameters(
    job_template=job_template,
    job_parameter_values={
        "Foo": "12"
    },
    job_template_dir=job_template_path,
    current_working_dir=Path(os.getcwd())
)
job = create_job(
    job_template=job_template,
    job_parameter_values=job_parameters
)

# stdout/stderr from the Session's running processes are sent to LOG
LOG.addHandler(logging.StreamHandler(stream=sys.stdout))

#   Run the Session
# ======
action_event = Event()
last_status: ActionStatus = None

def action_complete_callback(session_id: str, status: ActionStatus) -> None:
    # This function will be called by the Session when one of the processes
    # that was started has experienced a status change.
    # e.g. Completing as FAILED/SUCCEEDED, or an update to a progress message.
    global last_status
    last_status = status
    if status.state != ActionState.RUNNING:
        action_event.set()

# Run all tasks in the DemoStep within a Session
with Session(
    session_id="demo",
    job_parameter_values=job_parameters,
    callback=action_complete_callback
) as session:
    unwind_session: bool = False
    environment_ids = list[str]()
    step = job.steps[0]
    try:
        def run_environment(env):
            global status
            action_event.clear()
            id = session.enter_environment(environment=env)
            environment_ids.append(id)
            # enter_environment is non-blocking, wait for the process to complete
            action_event.wait()
            if last_status.state in (ActionState.CANCELED, ActionState.FAILED):
                raise RuntimeError("Abnormal exit")
        # Enter each job environment
        for env in job.jobEnvironments:
            run_environment(env)
        # Enter each step environment
        for env in step.stepEnvironments:
            run_environment(env)
        # Run each task in the step
        for task_parameters in StepParameterSpaceIterator(space=step.parameterSpace):
            action_event.clear()
            session.run_task(
                step_script=step.script,
                task_parameter_values=task_parameters
            )
            # run_task is non-blocking, wait for the process to complete
            action_event.wait()
            if last_status.state in (ActionState.CANCELED, ActionState.FAILED):
                raise RuntimeError("Abnormal exit")
    except RuntimeError:
        pass
    finally:
        # Exit all environments in the reverse order that they were entered.
        environment_ids.reverse()
        for _id in environment_ids:
            session.exit_environment(identifier=_id)
            action_event.clear()
            action_event.wait()

Impersonating a User

This library supports running its Session Actions as a different operating system user than the user that is running the library. In the following, we refer to the operating system user that is running this library as the host user and the user that is being impersonated to run actions as the actions user.

This feature exists to:

1. Provide a means to securely isolate the environment and files of the host user from the environment in which the Session Actions are run. Configure your filesystem permissions, and user groups for the host and actions users such that the actions user cannot read, write, or execute any of the host user files that it should not be able to.
2. Provide a way for you to permit access, on a per-Session basis, to specific local and shared filesystem assets to the running Actions running in the Session.

Impersonating a User: POSIX Systems

To run an impersonated Session on POSIX Systems modify the "Running a Session" example as follows:

...
from openjd.sessions import PosixSessionUser
...
user = PosixSessionUser($USERNAME$, password=$PASSWORD_OF_USERNAME$)
...
with Session(
    session_id="demo",
    job_parameter_values=job_parameters,
    callback=action_complete_callback,
    user=user
) as session:
    ...

You must ensure that the host user is able to run commands as the actions user with passwordless sudo by, for example, adding a rule like follows to your sudoers file or making the equivalent change in your user permissions directory:

host ALL=(actions) NOPASSWD: ALL

Impersonating a User: Windows Systems

To run an impersonated Session on Windows Systems modify the "Running a Session" example as follows:

...
from openjd.sessions import WindowsSessionUser
...
# If you're running in an interactive logon session (e.g. cmd or powershell on your desktop)
user = WindowsSessionUser($USERNAME$, password=$PASSWORD_OF_USERNAME$)
# If you're running in a Windows Service
user = WindowsSessionUser($USERNAME$, logon_token=user_logon_token)
# Where `user_logon_token` is a token that you have created that is compatible
# with the Win32 API: CreateProcessAsUser
...
with Session(
    session_id="demo",
    job_parameter_values=job_parameters,
    callback=action_complete_callback,
    user=user
) as session:
    ...

You must ensure that the Python installation hosting this code can be run by any impersonated user in addition to the host user. The library makes impersonated subprocess calls to perform operations dependent on the impersonated user file system permissions, such as finding files in search paths.

If running in a Windows Service, then you must ensure that:

1. The host user is an Administrator, LocalSystem, or LocalService user as your security posture requires; and
2. The host user has the Replace a process level token privilege.

Downloading

You can download this package from:

• PyPI
• GitHub releases

Verifying GitHub Releases

You can verify the authenticity of the release artifacts using the gpg command line tool.

1. Download the desired release artifacts from the GitHub releases page. Make sure to download the corresponding PGP signature file (ending with .sig) as well. For example, if you would like to verify your download of the wheel for version 1.2.3, you should have the following files downloaded:

   openjd_sessions-1.2.3-py3-none-any.whl
   openjd_sessions-1.2.3-py3-none-any.whl.sig
   

2. Install the gpg command line tool. The installation process varies by operating system. Please refer to the GnuPG website for instructions: https://gnupg.org/download/

3. Save the following contents to a file called openjobdescription-pgp.asc:

   -----BEGIN PGP PUBLIC KEY BLOCK-----
   
   mQINBGXGjx0BEACdChrQ/nch2aYGJ4fxHNQwlPE42jeHECqTdlc1V/mug+7qN7Pc
   C4NQk4t68Y72WX/NG49gRfpAxPlSeNt18c3vJ9/sWTukmonWYGK0jQGnDWjuVgFT
   XtvJAAQBFilQXN8h779Th2lEuD4bQX+mGB7l60Xvh7vIehE3C4Srbp6KJXskPLPo
   dz/dx7a+GXRiyYCYbGX4JziXSjQZRc0tIaxLn/GDm7VnXpdHcUk3qJitree61oC8
   agtRHCH5s56E8wt8fXzyStElMkFIZsoLDlLp5lFqT81En9ho/+K6RLBkIj0mC8G7
   BafpHKlxkrIgNK3pWACL93GE6xihqwkZMCAeqloVvkOTdfAKDHuDSEHwKxHG3cZ1
   /e1YhtkPMVF+NMeoQavykUGVUT1bRoVNdk6bYsnbUjUI1A+JNf6MqvdRJyckZqEC
   ylkBekBp/SFpFHvQkRCpfVizm2GSrjdZKgXpm1ZlQJyMRVzc/XPbqdSWhz52r3IC
   eudwReHDc+6J5rs6tg3NbFfPVfCBMSqHlu1HRewWAllIp1+y6nfL4U3iEsUvZ1Y6
   IV3defHIP3kNPU14ZWf3G5rvJDZrIRnjoWhDcaVmivmB/cSdDzphL5FovSI8dsPm
   iU/JZGQb3EvZq+nl4pOiK32hETJ/fgCCzgUA3WqGeFNUNSI9KYZgBe6daQARAQAB
   tDRPcGVuIEpvYiBEZXNjcmlwdGlvbiA8b3BlbmpvYmRlc2NyaXB0aW9uQGFtYXpv
   bi5jb20+iQJXBBMBCABBFiEEvBcWYrv5OB7Tl2sZovDwWbzECYcFAmXGjx0DGy8E
   BQkDwmcABQsJCAcCAiICBhUKCQgLAgMWAgECHgcCF4AACgkQovDwWbzECYcSHRAA
   itPYx48xnJiT6tfnult9ZGivhcXhrMlvirVYOqEtRrt0l18sjr84K8mV71eqFwMx
   GS7e4iQP6guqW9biQfMA5/Id8ZjE7jNbF0LUGsY6Ktj+yOlAbTR+x5qr7Svb7oEs
   TMB/l9HBZ1WtIRzcUk9XYqzvYQr5TT997A63F28u32RchJ+5ECAz4g/p91aWxwVo
   HIfN10sGzttoukJCzC10CZAVscJB+nnoUbB/o3bPak6GUxBHpMgomb0K5g4Z4fXY
   4AZ9jKFoLgNcExdwteiUdSEnRorZ5Ny8sP84lwJziD3wuamVUsZ1C/KiQJBGTp5e
   LUY38J1oIwptw5fqjaAq2GQxEaIknWQ4fr3ZvNYUuGUt5FbHe5U5XF34gC8PK7v7
   bT/7sVdZZzKFScDLfH5N36M5FrXfTaXsVbfrRoa2j7U0kndyVEZyJsKVAQ8vgwbJ
   w/w2hKkyQLAg3l5yO5CHLGatsfSIzea4WoOAaroxiNtL9gzVXzqpw6qPEsH9hsws
   HsPEQWXHmDQvFTNUU14qic1Vc5fyxCBXIAGAPBd20b+219XznJ5uBKUgtvnqcItj
   nMYe6Btxh+pjrTA15X/p81z6sB7dkL1hPHfawLhCEzJbIPyyBTQYqY00/ap4Rj7t
   kzSiyzBejniFfAZ6eYBWsej7uXUsVndBF1ggZynPTeE=
   =iaEm
   -----END PGP PUBLIC KEY BLOCK-----
   

4. Import the OpenPGP key for Open Job Description by running the following command:

   gpg --import --armor openjobdescription-pgp.asc
   

5. Determine whether to trust the OpenPGP key. Some factors to consider when deciding whether or not to trust the above key are:

   • The internet connection you’ve used to obtain the GPG key from this website is secure
   • The device that you are accessing this website on is secure

   If you have decided to trust the OpenPGP key, then edit the key to trust with gpg like the following example:

   $ gpg --edit-key A2F0F059BCC40987
   gpg (GnuPG) 2.0.22; Copyright (C) 2013 Free Software Foundation, Inc.
   This is free software: you are free to change and redistribute it.
   There is NO WARRANTY, to the extent permitted by law.
   
   
   pub  4096R/BCC40987  created: 2024-02-09  expires: 2026-02-08  usage: SCEA
                        trust: unknown       validity: unknown
   [ unknown] (1). Open Job Description <[e-mail]>
   
   gpg> trust
   pub  4096R/BCC40987  created: 2024-02-09  expires: 2026-02-08  usage: SCEA
                        trust: unknown       validity: unknown
   [ unknown] (1). Open Job Description <[e-mail]>
   
   Please decide how far you trust this user to correctly verify other users' keys
   (by looking at passports, checking fingerprints from different sources, etc.)
   
     1 = I don't know or won't say
     2 = I do NOT trust
     3 = I trust marginally
     4 = I trust fully
     5 = I trust ultimately
     m = back to the main menu
   
   Your decision? 5
   Do you really want to set this key to ultimate trust? (y/N) y
   
   pub  4096R/BCC40987  created: 2024-02-09  expires: 2026-02-08  usage: SCEA
                        trust: ultimate      validity: unknown
   [ unknown] (1). Open Job Description <[e-mail]>
   Please note that the shown key validity is not necessarily correct
   unless you restart the program.
   
   gpg> quit
   

6. Verify the signature of the Open Job Description release via gpg --verify. The command for verifying the example files from step 1 would be:

   gpg --verify ./openjd_sessions-1.2.3-py3-none-any.whl.sig ./openjd_sessions-1.2.3-py3-none-any.whl
   

Security

See CONTRIBUTING for more information.

License

This project is licensed under the Apache-2.0 License.