.. index:: developing LAVA

.. _lava_development:

LAVA development
################

Before you start, ensure you've read:

* :ref:`development_pre_requisites`
* :ref:`contribution_guide`
* :ref:`code_of_conduct`
* :ref:`criteria`.

.. seealso:: :ref:`contribute_upstream`

.. _running_all_unit_tests:

Run the unit tests
==================

Extra dependencies are required to run the tests. On Debian based
distributions, you can install ``lava-dev``.

To run the tests, use the ``ci-run`` script::

 $ ./ci-run

There is never any need to use ``sudo`` for unit tests, it causes lots
of complications by changing file permissions in your local git clone.

.. seealso:: :ref:`testing_pipeline_code` and
   :ref:`developer_preparations`

Functional testing
==================

Unit tests cannot replicate all tests required on LAVA code, some tests
will need to be run with real devices under test. On Debian based
distributions, see :ref:`dev_builds`. See :ref:`test_developer` for
information on writing LAVA test jobs to test particular device
functionality.

.. index:: git commit messages

.. _making_git_changes:

Make your changes
=================

* Follow PEP8 style for Python code.
* Use one topic branch for each logical change.
* Include new unit tests in the proposed merge request.
* Write good commit messages.

  * Describe why the change was made, not what files were changed.
    The commit message should reflect your intention, not the contents
    of the commit.

  * Avoid putting documentation into the commit message. Keep the
    commit message to a reasonable length (about 10 to 12 lines at
    most). Include changes to the existing documentation in your
    commit.

  * Usage examples need to go into the documentation, not the commit
    message. Everything which is intended to help users to add this
    support to their own test jobs must be in the documentation.

  * Avoid duplicating or summarizing the documentation in the commit
    message, reviewers will be reading the documentation as well.

  * Use comments in the code in preference to detailed commit messages.

.. index:: codestyle, black

.. _running_black:

Source code formatting
----------------------

`black` and `isort` should be applied to **all** LAVA source code files.
Merge requests will **fail** CI if a change breaks the formatting.

`isort` should be run with `--profile black` option to ensure
compatibility with black.

When changing files formatted by black, make your changes and then run
``black`` on all modified Python files before pushing the branch to
GitLab. In some situations, ``black`` and ``pylint`` can disagree on
continuation of long lines, particularly when using multiple operators
and bracketing. In case of conflict, **black is always correct**. If
you disagree with how `black` has formatted your change, consider
expanding list comprehensions and other syntax until you and black can
agree.

.. index:: developer: adding unit tests

.. _developer_adding_unit_tests:

Add some unit tests
===================

Some changes will **always** need additional unit tests and reviews
will not be merged without this support. The purpose is to ensure that
future changes in the codebase have some assurance that existing
support has not been affected. The intent is that as much as possible
of the test job and device configuration is covered by at least one
unit test. Some examples include:

#. Changes to an existing jinja2 device-type template which change the
   output YAML of the device configuration need a unit test to show that
   the change is being included.

#. Adding a new deployment or boot method needs unit tests (including
   sample test jobs) which check that all ``validate()`` functions work
   correctly and particular tests checking for the specific details of
   the new method.

#. Adding a change to an existing deployment or boot method which
   changes the construction of the pipeline based on test job or device
   configuration. Unit tests will be required to show that the change is
   being made.

Reviewers may ask for unit test support for any change, so :ref:`talk
to us <getting_support>` during development. You can also use an
``WIP:`` prefix in your git commit to indicate that the change is not
ready for merging but is ready for comments.

lava_dispatcher
---------------

Whenever new functionality is added to ``lava_dispatcher``, especially
a new :ref:`Strategy class <using_strategy_classes>`, there **must** be
some new unit tests added to allow some assurance that the new classes
continue to operate as expected as the rest of the codebase continues
to develop. There are a lot of examples in the current unit tests.

#. Start with a sample test job which is known to work. Copy that into
   ``lava_dispatcher/tests/sample_jobs``. The URLs in that sample job
   will need to be valid URLs but do not need to be working files.
   (This sample_job is not being submitted to run on a device, it is
   only being used to check that the construction of the pipeline is
   valid.) If you need files which other sample jobs do not use then
   :ref:`we can help with that <getting_support>` by putting files onto
   images.validation.linaro.org.

#. Use the updated ``Factory`` support to generate the device
   configuration directly from the ``lava_scheduler_app`` templates.

   If a suitable device dictionary does not already exist in
   ``lava_scheduler_app/tests/devices``, a new one can be added to
   support the unit tests.

#. Add a function to a suitable Factory class to use the device config
   file to create a device and use the parser to create a Job instance
   by following the examples in the existing unit tests

#. Create the pipeline ref by following the ``readme.txt`` in the
   ``pipeline_ref`` directory. The simplest way to create a single new
   pipeline reference file is to add one line to the new unit test
   function:

   .. code-block:: python

    self.update_ref = True

   Run the unit test and the pipeline reference will be created. Remove
   the line before committing for review or the ``./ci-run`` check will
   fail.

   This file acts as a description of the classes involved in the
   pipeline which has been constructed from the supplied test job and
   device configuration. Validating it in the unit tests ensures that
   later development does not invalidate the new code by accidentally
   removing or adding unexpected actions.

#. In the new function, use the ``pipeline_refs`` README to add a check
   that the pipeline reference continues to reflect the pipeline which
   has been constructed by the parser.

.. note:: unit tests do not typically check any of the ``run`` function
   code. Do as much checking as is practical in the ``validate``
   functions of all the new classes. For example, if ``run`` relies on
   a parameter being set, check for that parameter in ``validate`` and
   check that the value of that parameter is correct based on the
   sample job and the supplied device configuration.

lava_scheduler_app
------------------

Some parts of lava_scheduler_app are easier to test than others. New
device-type templates need to have specific unit tests added to
``tests/lava_scheduler_app/test_templates`` or one of the relevant
specialist template unit test files. Follow the examples and make sure
that if the new template adds new items then those items are checked
for existence and validity in the new function which tests the new
template.

.. code-block:: shell

 $ python3 -m unittest -vcf tests.lava_scheduler_app.test_fastboot_templates

 $ python3 -m unittest -vcf tests.lava_scheduler_app.test_qemu_templates

 $ python3 -m unittest -vcf tests.lava_scheduler_app.test_uboot_templates

If you are adding or modifying documentation in ``lava-server``, make sure that
the documentation builds cleanly:

.. code-block:: none

 $ make -C doc/v2 clean
 $ make -C doc/v2 html

For other parts of ``lava-server``, follow the examples of the existing unit
tests and :ref:`talk to us <getting_support>`.

Re-run the unit tests
=====================

Make sure that your changes do not cause any failures in the unit tests::

 $ ./ci-run

Wherever possible, always add new unit tests for new code.

Testing local changes
=====================

For any sufficiently large change, :ref:`building <dev_builds>` and
installing a new package on a local instance is recommended. Ensure
that the test instance is already running the most recent production
release.

If the test instance has a separate worker, ensure that the master and
the worker always have precisely the same code applied. For some
changes, it may be necessary to have a test instance which is a clone
of a production instance, complete with devices. **Never** make live
changes to a production instance. (This is why integrating new device
types into LAVA requires multiple devices.)

Once your change is working successfully:

#. Ensure that your local branch is clean - check for left over debug
   code.

#. Ensure that your local branch has been rebased against current
   ``master``

#. Build and install a package from the ``master`` branch. If you have
   added any new files in your local change, make sure these have been
   removed. Reproduce the original bug or problem.

#. Build and install a package from your local branch and repeat the
   tests.

lava_dispatcher
---------------

Changes to most files in ``lava_dispatcher`` can be symlinked or copied
into the packaged locations. e.g.::

 $ PYTHONDIR=/usr/lib/python3/dist-packages/
 $ sudo cp <path_to_file> $PYTHONDIR/<path_to_file>

.. note:: The path used for ``PYTHONDIR`` has changed with the LAVA
   runtime support moving to Python3 in 2018.4.

There is no need to copy files used solely by the unit tests.

Changes to files in ``./etc/`` will require restarting the relevant
service.

Changes to files in ``./lava/dispatcher/`` will need the ``lava-worker``
service to be restarted but changes to ``./lava_dispatcher/`` will not.

* When adding or modifying ``run``, ``validate``, ``populate`` or
  ``cleanup`` functions, **always** ensure that ``super`` is called
  appropriately, for example:

  .. code-block:: python

    super().validate()

    connection = super().run(connection, max_end_time)

* When adding or modifying ``run`` functions in subclasses of
  ``Action``, **always** ensure that each return point out of the
  ``run`` function returns the ``connection`` object:

  .. code-block:: python

    return connection

* When adding new classes, use **hyphens**, ``-``, as separators in
  ``self.name``, *not underscores*,  ``_``. The function will fail if
  underscore or whitespace is used. Action names need to all be
  lowercase and describe something about what the action does at
  runtime. More information then needs to be added to the
  ``self.summary`` and an extended sentence in ``self.description``.

  .. code-block:: python

    self.name = 'do-something-at-runtime'

  .. seealso:: :ref:`developing_new_classes`

* Use **namespaces** for all dynamic data. Parameters of actions are
  immutable. Use the namespace functions when an action needs to store
  dynamic data, for example the location of files which have been
  downloaded to temporary directories, Do not access ``self.data``
  directly (except for use in iterators). Use the get and set
  primitives, for example:

  .. code-block:: python

   set_namespace_data(action='boot', label='shared', key='boot-result', value=res)

   image_arg = self.get_namespace_data(action='download-action', label=label, key='image_arg')

lava-server
-----------

Changes to device-type templates and device dictionaries take effect
immediately, so simply submitting a test job will pick up the latest
version of the code in
``/etc/lava-server/dispatcher-config/device-types/``. Make changes to
the templates in ``lava_scheduler_app/tests/device-types/``. Check them
using the ``test_all_templates`` test, and only then copy the updates
into ``/etc/lava-server/dispatcher-config/device-types/`` when the
tests pass.

.. seealso:: :ref:`testing_new_devicetype_templates`

Changes to django templates can be applied immediately by copying the
template into the packaged path, e.g. html files in
``lava_scheduler_app/templates/lava_scheduler_app/`` can be copied or
symlinked to
``/usr/lib/python3/dist-packages/lava_scheduler_app/templates/lava_scheduler_app/``

.. note:: The path changed when the LAVA runtime support moved to
   Python3 with the 2018.4 release.

Changes to python code generally require copying the files and
restarting the ``lava-server-gunicorn`` service before the changes will
be applied::

 sudo service lava-server-gunicorn restart

Changes to ``lava_scheduler_app/models.py``,
``lava_scheduler_app/db_utils.py`` or ``lava_results_app/dbutils`` will
require restarting the ``lava-master`` service::

 sudo service lava-master restart

Changes to files in ``./etc/`` will require restarting the relevant
service. If multiple services are affected, it is normally best to
build and install a new package.

:ref:`database_migrations` are a complex area - read up on the django
documentation for migrations. Instead of ``python ./manage.py``, use
``sudo lava-server manage``.

lava-server-doc
---------------

Documentation files in ``doc/v2`` can be built locally in the git
checkout using ``make``::

 make -C doc/v2 clean
 make -C doc/v2 html

Files can then be checked in a web browser using the ``file://`` url
scheme and the ``_build/html/`` subdirectory. For example:
``file:///home/neil/code/lava/lava-server/doc/v2/_build/html/first_steps.html``

Some documentation changes can add images, example test jobs, test
definitions and other files. Depending on the type of file, it may be
necessary to make changes to the packaging, so :ref:`talk to us
<getting_support>` before making such changes.

Documentation is written in RST, so the `RST Primer
<http://www.sphinx-doc.org/en/stable/rest.html>`_ is essential reading
when modifying the documentation.

#. Keep all documentation paragraphs wrapped to 80 columns.

#. Strip trailing whitespace from all modified files.

#. When you build your changes from clean, make sure there are no
   warning or error messages from the build.

#. Use ``en_US`` in both code and documentation.

#. Use syntax highlighting for code and check the rendered page. For
   example, ``code-block:: shell`` relates to the contents of shell
   scripts, not the output of commands or scripts in a shell (those
   should use ``code-block:: none``)

#. Wherever possible, pull in code samples from working example files
   so that these can be checked for accuracy on `staging
   <https://staging.validation.linaro.org/>`_ before future releases.

.. _developer_commit_for_review:

Debugging lava-dispatcher with pdb, the Python debugger
=======================================================

Due to the nature of how ``lava-run`` is executed by ``lava-worker``, it's
tricky to debug ``lava-dispatcher`` directly. However, one can use the
`remote-pdb`_ package and do remote debugging.

.. _remote-pdb: https://pypi.org/project/remote-pdb/


You need to have the ``remote-pdb`` python package installed, and a ``telnet``
client.

If ``lava-worker`` is started with the ``--debug`` command line option, then it
will make ``lava-run`` stop right before running the test job for debugging.
You will see a message on the console where ``lava-run`` is running that is
similar to this::

    RemotePdb session open at 127.0.0.1:37865, waiting for connection ...

Note the address where the debugging server is listening.  Then, to access the
debugger, you point ``telnet`` to the provided address and port::

    telnet 127.0.0.1 37865
    Connected to 127.0.0.1.
    Escape character is '^]'.
    > /path/to/lava/dispatcher/lava-run(274)main()
    -> job.run()
    (Pdb)

From that point on, you have a normal `pdb`_ session, and can debug the
execution of ``lava-dispatcher``.

.. _pdb: https://docs.python.org/3/library/pdb.html

Send your commits for review
============================

From each topic branch, just run::

    git push

#. each merge request is reviewed and approved individually and

#. later commits will depend on earlier commits, so if a later commit
   is approved and the one before it is not, the later commit will not
   be merged until the earlier one is approved.

#. you are responsible for **rebasing** your branch(es) against updates
   on master and this can become more difficult when there are multiple
   commits on one local branch.

#. Fixes from comments or unit test failures in one review are **not**
   acceptable as separate merge requests.

#. It is common for merge requests to go through repeated cycles of
   comments and updates. This is not a reflection on the usefulness of
   the change or on any particular contributors, it is a natural
   evolution of the code. Comments may reflect changes being made in
   other parallel reviews or reviews merged whilst this change was
   being reviewed. Contributors may be added to other reviews where the
   team consider this to be useful for feedback or where the
   documentation is being updated in areas which relate to your change.
   The number of comments per review is no indication of the quality of
   that review and does not affect when the review would be merged.

#. It is common for changes to develop merge conflicts during the
   review process as other reviews are merged. You are responsible for
   fixing all merge conflicts in your merge requests.

#. All merge requests must pass all CI tests.

Therefore the recommendations are:

#. **Always** use a separate local branch per change and a new commit
   for changes on that branch each time branch gets pushed until it
   is merged.

#. Think carefully about whether to base one local branch on another
   local branch. This is recommended when one change logically extends
   an earlier change and makes it a lot easier than having multiple
   commits on a single branch.

#. Keep all your branches up to date with master **regularly**. It is
   much better to resolve merge conflicts one change at a time instead
   of having multiple merge commits all in the one rebase operation
   when the merge request is finally ready to be merged. GitLab will
   show a message if a rebase is required but you can also simply
   rebase your local branch before pushing any new changes.

#. Check gitlab periodically and ensure that you address **all**
   comments on the review.

.. _developer_adding_reviewers:

Adding reviewers
================

The lava group is automatically added as approver for every merge
request.

Optionally, you can put ``WIP:`` at the start of your git commit
message and then amend the message when the request is ready to merge.

Handling your local branches
============================

After placing a few reviews, there will be a number of local branches.
To keep the list of local branches under control, the local branches
can be easily deleted after the merge. Note: git will warn if the
branch has not already been merged when used with the lower case ``-d``
option. This is a useful check that you are deleting a merged branch
and not an unmerged one, so work with git to help your workflow.

::

    $ git switch bugfix
    $ git rebase master
    $ git switch master
    $ git branch -d bugfix


If the final command fails, check the status of the review of the
branch. If you are completely sure the branch should still be deleted
or if the review of this branch was abandoned, use the `-D` option
instead of `-d` and repeat the command.

Future proofing
===============

All developers are encouraged to write code with future changes in
mind, so that it is easy to do a technology upgrade. This includes
watching for errors and warnings generated by dependency packages, as
well as upgrading and migrating to newer APIs as a normal part of
development.

This is particularly true for Django where the ``lava-server`` package
needs to retain support for multiple django versions as well as
monitoring for deprecation warnings in the newest django version. Where
necessary, write code for different versions and separate with:

.. code-block:: python

 import django
 if django.VERSION > (1, 8):
     pass  # newer code
 else:
     pass  # older compatibility code

.. _use_templates_in_dispatcher:

Use templates to generate device configuration
==============================================

One of the technical reasons to merge the lava-dispatcher and
lava-server source trees into a single source is to allow
lava-dispatcher to use the output of the lava-server templates in
development. Further changes are being made in this area to provide a
common module but it is already possible to build a lava_dispatcher
unit test which pulls device configuration directly from the templates
in lava_scheduler_app. This removes the problem of static YAML files in
``lava_dispatcher/devices`` getting out of date compared to the actual
YAML created by changes in the templates.

The YAML device configuration is generated from a device dictionary in
``lava_scheduler_app`` which extends a template in
``lava_scheduler_app`` - the same template which is used at runtime on
LAVA instances. Any change to the template or device dictionary is
immediately reflected in the YAML sent to the ``lava_dispatcher`` unit
test.

.. code-block:: python

    import unittest
    from tests.lava_dispatcher.test_basic import Factory, LavaDispatcherTestCase
    from tests.lava_dispatcher.utils import infrastructure_error_multi_paths

    class TestFastbootDeploy(LavaDispatcherTestCase):  # pylint: disable=too-many-public-methods

        def setUp(self):
            super().setUp()
            self.factory = Factory()

        @unittest.skipIf(infrastructure_error_multi_paths(
            ['lxc-info', 'img2simg', 'simg2img']),
            "lxc or img2simg or simg2img not installed")
        def test_lxc_api(self):
            job = self.factory.create_job('d02-01.jinja2', 'sample_jobs/grub-ramdisk.yaml')


.. _database_migrations:

Database migrations
===================

The LAVA team recommend using Debian stable but also support testing
and unstable which have a newer version of `python-django
<https://tracker.debian.org/pkg/python-django>`_.

Database migrations on Debian Jessie and later are managed within
django. Support for `python-django-south
<https://tracker.debian.org/pkg/python-django-south>`_ has been
**dropped**. **Only django** migration types should be included in any
reviews which involve a database migration.

Once modified, the updated ``models.py`` file needs to be copied into
the system location for the relevant extension, e.g.
``lava_scheduler_app``. This is a step which needs to be done by the
developer - developer packages **cannot** be installed cleanly and
**unit tests will likely fail** until the migration has been created
and applied.

On Debian Jessie and later::

 $ sudo lava-server manage makemigrations lava_scheduler_app

The migration file will be created in
``/usr/lib/python3/dist-packages/lava_scheduler_app/migrations/``
(which is why ``sudo`` is required) and will need to be copied into
your git working copy and added to the review.

The migration is applied using::

 $ sudo lava-server manage migrate lava_scheduler_app

See `django docs
<https://docs.djangoproject.com/en/3.2/topics/migrations/>`_ for more
information.

.. index:: developer: use python3

.. _use_python3:

Python 3.x
==========

Python3 support in LAVA is related to a number of factors:

* Forthcoming LTS releases of django which will remove support for
  python2.7

* Transition within Debian to full python3 support.

https://lists.lavasoftware.org/archives/list/lava-announce@lists.lavasoftware.org/thread/6QEDKDIQ2GFEPK5SRIE36RV234NSLSB6/

https://lists.lavasoftware.org/archives/list/lava-announce@lists.lavasoftware.org/thread/KWEPRA5P2LGVZ6WPIBWCYLC3G6TD5SN6/

lava-dispatcher and lava-server now fully support python3, runtime and
testing. Code changes to either codebase **must** be Python3
compatible.

All reviews run the ``lava-dispatcher`` and ``lava-server`` unit tests
against python 3.x and changes must pass all unit tests.

The ``./ci-run`` script for ``lava-dispatcher`` and ``lava-server`` can
run the unit tests using Python3::

 ./ci-run -a

Some additional Python3 dependencies will be required. In particular,
``python3-django-auth-ldap`` will need to be installed.

.. warning:: Django will be dropping python2.7 support with the 2.2LTS
   release, *frozen* instances of LAVA will not be able to use django
   updates after that point.

XML-RPC changes
===============

Each of the installed django apps in ``lava-server`` are able to expose
functionality using :ref:`XML-RPC <xml_rpc>`.

.. code-block:: python

 from linaro_django_xmlrpc.models import ExposedAPI

 class SomeAPI(ExposedAPI):

#. The ``docstring`` **must** include the full user-facing documentation of
   each function exposed through the API.

#. Authentication should be supported using the base class support:

   .. code-block:: python

    self._authenticate()

#. Catch exceptions for all errors, ``SubmissionException``,
   ``DoesNotExist`` and others, then re-raise as
   ``xmlrpc.client.Fault``.

#. Move as much of the work into the relevant app as possible, either
   in ``models.py`` or in ``dbutils.py``. Wherever possible, reuse
   existing functions with wrappers for error handling in the API code.

.. _lava_instance_settings:

Instance settings
=================

``/etc/lava-server/instance.conf`` is principally for V1 configuration.
V2 uses this file only for the database connection settings on the
master, instance name and the ``lavaserver`` user.

Most settings for the instance are handled inside django using
``/etc/lava-server/settings.conf``. (For historical reasons, this file
uses **JSON** syntax.)

.. seealso:: :ref:`branding`, :ref:`django_debug_toolbar` and
   :ref:`developer_access_to_django_shell`

.. _pylint_tool:

Pylint3
=======

`Pylint`_ is a tool that checks for errors in Python code, tries to
enforce a coding standard and looks for bad code smells. We encourage
developers to run LAVA code through pylint and fix warnings or errors
shown by pylint to maintain a good score. For more information about
code smells, refer to Martin Fowler's `refactoring book`_. LAVA
developers stick on to `PEP 008`_ (aka `Guido's style guide`_) across
all the LAVA component code.

``pylint3`` does need to be used with some caution, the messages
produced should not be followed blindly. It can be very useful for
spotting unused imports, unused variables and other issues. To simplify
the pylint output, some warnings are recommended to be disabled::

 $ pylint3 -d line-too-long -d missing-docstring

.. note:: Docstrings should still be added wherever a docstring would
   be useful.

Many developers use a ``~/.pylintrc`` file which already includes a
sample list of warnings to disable. Other warnings frequently disabled
in ``~/.pylintrc`` include:

.. code-block:: none

        too-many-locals,
        too-many-ancestors,
        too-many-arguments,
        too-many-instance-attributes,
        too-many-nested-blocks,
        too-many-return-statements,
        too-many-branches,
        too-many-statements,
        too-few-public-methods,
        wrong-import-order,
        ungrouped-imports,

``pylint`` also supports local disabling of warnings and there are many
examples of:

.. code-block:: python

 variable = func_call()  # pylint: disable=

There is a ``pylint-django`` plugin available in unstable and testing
and whilst it improves the pylint output for the ``lava-server``
codebase, it still has a high level of false indications, particularly
when extending an existing model.

pep8
====

In order to check for `PEP 008`_ compliance the following command is
recommended::

  $ pep8 --ignore E501

`pep8` can be installed in Debian based systems as follows::

  $ apt install pep8

.. index:: unit tests

.. _unit_tests:

Unit-tests
==========

LAVA has set of unit tests which the developers can run on a regular
basis for each change they make in order to check for regressions if
any. Most of the LAVA components such as ``lava-server``,
``lava-dispatcher``, :ref:`lavacli <lavacli>` have unit tests.

Extra dependencies are required to run the tests. On Debian based
distributions, you need to install ``lava-dev``.

.. seealso:: :ref:`unit_test_dependencies`

To run the tests, use the ci-run / ci-build scripts::

  $ ./ci-run

.. _`Pylint`: https://www.pylint.org/
.. _`refactoring book`: https://www.refactoring.com/
.. _`PEP 008`: https://www.python.org/dev/peps/pep-0008/
.. _`Guido's style guide`: https://www.python.org/doc/essays/styleguide.html

.. seealso:: :ref:`developer_preparations`,
   :ref:`unit_test_dependencies` and :ref:`testing_pipeline_code` for
   examples of how to run individual unit tests or all unit tests
   within a class or module.

LAVA database model visualization
=================================

LAVA database models can be visualized with the help of
`django_extensions`_ along with tools such as `pydot`_. In Debian based
systems install the following packages to get the visualization of LAVA
database models:

.. code-block:: shell

 $ apt install python-django-extensions python-pydot

Once the above packages are installed successfully, use the following command
to get the visualization of ``lava-server`` models in PNG format:

.. code-block:: shell

 $ sudo lava-server manage graph_models --pydot -a -g -o lava-server-model.png

More documentation about graph models is available in
https://django-extensions.readthedocs.io/en/latest/graph_models.html

Other useful features from `django_extensions`_ are as follows:

* `shell_plus`_ - similar to the built-in "shell" but autoloads all models

* `validate_templates`_ - check templates for rendering errors:

  .. code-block:: shell

   $ sudo lava-server manage validate_templates

* `runscript`_ - run arbitrary scripts inside ``lava-server``
  environment:

  .. code-block:: shell

   $ sudo lava-server manage runscript fix_user_names --script-args=all

.. _`django_extensions`: https://django-extensions.readthedocs.io/en/latest/
.. _`pydot`: https://pypi.org/project/pydot/
.. _`shell_plus`: https://django-extensions.readthedocs.io/en/latest/shell_plus.html
.. _`validate_templates`: https://django-extensions.readthedocs.io/en/latest/validate_templates.html
.. _`runscript`: https://django-extensions.readthedocs.io/en/latest/runscript.html

.. _developer_access_to_django_shell:

Developer access to django shell
================================

Default configurations use a side-effect of the logging behavior to
restrict access to the ``lava-server manage`` operations which typical
Django apps expose through the ``manage.py`` interface. This is because
``lava-server manage shell`` provides read-write access to the
database, so the command requires ``sudo``.

On developer machines, this can be unnecessary. Set the location of the
django log to a new location to allow easier access to the management
commands to simplify debugging and to be able to run a Django Python
Console inside a development environment. In
``/etc/lava-server/settings.conf`` add::

 "DJANGO_LOGFILE": "/tmp/django.log"

.. note:: ``settings.conf`` is JSON syntax, so ensure that the previous
   line ends with a comma and that the resulting file validates as
   JSON. Use `JSONLINT <https://jsonlint.com>`_

The new location needs to be writable by the ``lavaserver`` user (for
use by localhost) and by the developer user (but would typically be
writeable by anyone).
