Before you start, ensure you’ve read the Pre-requisites to start with development.
See also
This is a short guide on how to send your patches to LAVA. The LAVA team uses the gerrit code review system to review changes.
If you do not already have a Linaro account, you will first need to Register with Linaro as a Community contributor.
So the first step will be logging in to gerrit and uploading you SSH public key there.
There are two main components to LAVA, lava-server
and
lava-dispatcher
.
git clone https://git.linaro.org/git/lava/lava-server.git
cd lava-server
git clone https://git.linaro.org/git/lava/lava-dispatcher.git
cd lava-dispatcher
There is also lava-tool
which is gaining more support for operations
involving the Lava Dispatcher Design:
git clone https://git.linaro.org/git/lava/lava-tool.git
cd lava-tool
If you have not done so already, git review
needs to be setup for each
clone of each source:
git review -s
We recommend never working off the master branch (unless you are a git expert and really know what you are doing). You should create a topic branch for each logically distinct change you work on.
Note
Unless your change directly depends on changes made in an earlier commit on a branch, this means making a fresh branch for each change with one commit per branch.
Before you start, make sure your master branch is up to date:
git checkout master
git pull
Now create your topic branch off master:
git checkout -b my-change master
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
..seealso:: Testing the new design and Preparing for LAVA development
It is essential to run pep8 --ignore E501
routinely on your local
changes as ./ci-run
will fail on any PEP8 errors.
Note
There can be differences in behaviour between pep8
in Jessie
and in Stretch or unstable. All reviews are tested using Jessie.
It is important to run tools like pylint, particularly when adding new files, to check for missing or unused imports. Other analysis tools should also be used, for example from within your IDE.
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 Developer package build. See Writing a LAVA test shell definition for information on writing LAVA test jobs to test particular device functionality.
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.
For any sufficiently large change, building 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:
master
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.Changes to most files in lava-dispatcher
can be symlinked or copied into
the packaged locations. e.g.:
PYTHONDIR=/usr/lib/python2.7/dist-packages/
sudo cp <path_to_file> $PYTHONDIR/<path_to_file>
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-slave
service to be restarted.
When adding or modifying run
, validate
, populate
or cleanup
functions, always ensure that super
is called appropriately, for example:
super(ThisClass, self).validate()
connection = super(ThisClass, self).run(connection, max_end_time, args)
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:
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
.
self.name = 'do-something-at-runtime'
See also
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:
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')
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.
See also
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/python2.7/dist-packages/lava_scheduler_app/templates/lava_scheduler_app/
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.
Database migrations are a complex area - read up on the django
documentation for migrations. Instead of python ./manage.py
, use
sudo lava-server manage
.
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 talk to us before making such changes.
Documentation is written in RST, so the RST Primer is essential reading when modifying the documentation.
en_GB
unless referring to elements of code which use en_US
.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
)From each topic branch, just run:
git review
If you have multiple commits in that topic branch, git review will warn you. It’s OK to send multiple commits from the same branch, but note that:
-1
by lava-bot
, a reviewer or the author,
the team will generally ignore that review unless it relates to parallel work on
a bug fix or other feature.Therefore the recommendations are:
Reviews submitted for lava-server
, lava-dispatcher
and lava-tool
will automatically have the LAVA software team added as reviewers when the
review is first submitted.
Other reviewers can also be added to individual reviews. The Owner of the
review is always added. Reviewers will get email for all changes relating to
that review. All reviewers need to Register with Linaro as a Community contributor, email will go to the
@linaro.org
account of that reviewer.
If you know that there are still problems to fix in the review, please use the
Gerrit interface to reply to the review and give the review a score of -1
and summarize your concerns in the comment. This indicates to the software team
that this review should not be considered for merging into master at this time.
You may still get comments.
Optionally, you can put [RFC]
or similar at the start of your git commit
message and then amend the message when the review is ready to merge.
When reviewers make comments on your change, you should amend the original commit to address the comments, and not submit a new change addressing the comments while leaving the original one untouched.
Gerrit handles this by adding a ChangeId to your commit message. Keep this Id unchanged when amending commit messages.
Locally, you can make a separate commit addressing the reviewer comments, it’s not a problem. But before you resubmit your branch for review, you have to rebase your changes against master to end up with a single, enhanced commit. For example:
$ git branch
master
* my-feature
$ git show-branch master my-feature
! [master] Last commit on master
! [my-feature] address reviewer comments
--
+ [my-feature] address reviewer comments
+ [my-feature^] New feature or bug fix
-- [master] Last commit on master
$ git rebase -i master
git rebase -i
will open your $EDITOR
and present you with something
like this:
pick xxxxxxx New feature or bug fix
pick yyyyyyy address reviewer comments
You want the last commit to be combined with the first and keep the first
commit message, so you change pick
to fixup
ending up with something
like this:
pick xxxxxxx New feature or bug fix
fixup yyyyyyy address reviewer comments
If you also want to edit the commit message of the first commit to mention
something else, change pick
to reword
and you will have the chance to
do that. Just remember to keep the Change-Id
unchanged.
NOTE: if you want to abort the rebase, just delete everything, save
the file as empty and exit the $EDITOR
.
Now save the file and exit your $EDITOR
.
In the end, your original commit will be updated with the changes:
$ git show-branch master my-feature
! [master] Last commit on master
! [my-feature] New feature or bug fix
--
+ [my-feature] New feature or bug fix
-- [master] Last commit on master
Note that the “New feature or bug fix” commit is now not the same as before
since it was modified, so it will have a new hash (zzzzzzz
instead of the
original xxxxxxx
). But as long as the commit message still contains the
same Change-Id
, gerrit will know it is a new version of a previously
submitted change.
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 checkout bugfix
$ git rebase master
$ git checkout 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.
If you haven’t got a clone handy on the instance to be used for the review, prepare a clone as usual.
Gerrit provides a number of ways to apply the changes to be reviewed, so set up a test branch as usual - always ensuring that the master branch of the clone is up to date before creating the review branch.
$ git checkout master
$ git pull
$ git checkout -b review-111
To pull in the changes in the review already marked for commit in your local
branch, use the pull
link in the patch set of the review you want to run.
Alternatively, to pull in the changes as plain patches, use the patch`
link
and pipe that to patch -p1
. In this full example, the second patch set of
review 159 is applied to the review-159
branch as a patch set.
$ git checkout master
$ git pull
$ git checkout -b review-159
$ git fetch https://review.linaro.org/lava/lava-server refs/changes/59/159/2 && git format-patch -1 --stdout FETCH_HEAD | patch -p1
$ git status
Handle the local branch as normal. If the reviewed change needs modification and a new patch set is added, revert the local change and apply the new patch set.
All developers are encouraged to write code with futuristic changes in mind, so that it is easy to do a technology upgrade, which 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:
import django
if django.VERSION > (1, 8):
pass # newer code
else:
pass # older compatibility code
LAVA recommends Debian Jessie but also supports testing and unstable which have a newer version of python-django.
Database migrations on Debian Jessie and later are managed within django. Support for 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/python2.7/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 for more information.
Python3 support in LAVA is related to a number of factors:
https://lists.linaro.org/pipermail/lava-announce/2017-June/000032.html
LAVA dispatcher now supports python3 testing but only for the pipeline unit
tests. Code changes to the V2 dispatcher code (i.e. in the
lava_dispatcher/pipeline
tree) must be sufficiently aware of Python3 to
not break the unit tests when run using python3.
LAVA is not yet ready to use python 3.x support at runtime, particularly in
lava-server, due to the lack of python 3.x support in the V1 code. However
it is good to take python 3.x support into account in lava-server
, when
writing new code for LAVA v2, so that it makes it easy during the move anytime
in the future.
All reviews run the lava-dispatcher.pipelnie
V2 unit tests against python
3.x and changes must pass without breaking compatibility with python 2.x
The ./ci-run
script for lava-dispatcher
shows how to run the python3
unit tests:
# to run python3 unit tests, you can use
# python3 -m unittest discover -v lava_dispatcher.pipeline
# but the python3 dependencies are not automatically installed.
The list of python3 dependencies needed for the pipeline unit tests is maintained as part of the functional tests:
https://git.linaro.org/lava-team/refactoring.git/tree/functional/dispatcher-pipeline-python3.yaml
From time to time, reviews may add more python dependencies - check on the Mailing lists if your tests start to fail after rebasing on current master or if you want to help with more python3 support in LAVA V2.
Warning
Avoid making changes to LAVA V1 code for python3 - only LAVA V2 is going to support python3. Also note that as django wil 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.
Each of the installed django apps in lava-server
are able to expose
functionality using XML-RPC.
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:
self._authenticate()
Catch exceptions for all errors, SubmissionException
, DoesNotExist
and others, then re-raise as xmlrpclib.Fault
.
Move as much of the work into the relevant app as possible, either in
models.py
or in dbutils.py
. Wherever possible, re-use existing
functions with wrappers for error handling in the API code.
/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.)
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.
pylint
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:
$ pylint -d line-too-long -d missing-docstring
Note
Docstrings should still be added wherever a docstring would be useful.
pylint
also supports local disabling of warnings and there are many
examples of:
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.
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
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
, lava-tool have 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 / ci-build scripts:
$ ./ci-run
See also
Preparing for LAVA development and Testing the new design for examples of how to run individual unit tests or all unit tests within a class or module.
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:
$ 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:
$ 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.org/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:
$ sudo lava-server manage validate_templates
runscript - run arbitrary scripts inside lava-server
environment:
$ sudo lava-server manage runscript fix_user_names --script-args=all
Default configurations use a side-effect of the logging behaviour 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
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).