Developing LAVA on Debian

LAVA no longer supports development on Ubuntu.

Packages for LAVA are available for:

  • Debian Buster (testing)

  • Debian Sid (unstable)

When using the packages to develop LAVA, there is a change to the workflow compared to the old lava-deployment-tool buildouts.


Changes to build dependencies between Debian versions can cause changes to the builds for each suite. Always ensure that you build packages for unstable using unstable and build packages for stable using a chroot or VM or other stable environment. If a package built on unstable does not install on stable, rebuild the same changes in a stable environment and re-install. Backports to stable in Debian are always built in a stable chroot or VM for this reason.

Why Debian?

In the very early stages, LAVA was deployed using a custom script based on PyPi and a lot of manual effort. This deployment tool frequently failed in complex and unexpected ways. It become clear that this would block successful and reliable deployment and upgrades of LAVA, particularly in larger scale environments.

The main LAVA developer at the time was also a Debian developer with the rights and familiarity with Debian to convert the deployment tool into a packaged format which solved these issues.

LAVA is not inherently tied to Debian but following the route of packaging LAVA in Debian solved many issues very easily. By using a well supported and readily understood distribution as our base, many users have been able to install and operate LAVA without needing direct help from the developers. We have also gained a stable and reliable platform for our internal CI which was an enormous aid during the V2 development cycle.

Whilst it might seem that lots of developer time is spent doing Debian specific development, equivalent (and possibly more) work would be needed to develop and support LAVA on any platform. Debian provides a very large collection of packaged software, removing the need for us to package and maintain the full stack which LAVA needs.

Options for other distributions

Although LAVA is not inherently tied to the Debian distribution, there would be some work involved to ensure that another method of deploying LAVA would work well enough for the upstream LAVA team to officially support that method.

On top of developing LAVA itself, full support of LAVA in Debian includes:

  1. Maintenance of packaging code, either upstream or in a public git repository.

  2. Preparation of LAVA releases for inclusion into the distribution.

  3. Rights to upload LAVA releases to the distribution and access within the distribution to apply local patches, upload security fixes and provide for backporting newer dependencies to maintain support for existing releases.

  4. Maintenance of a LAVA lab using this distribution and running CI on LAVA devices. (This is to ensure that the functionality of LAVA is being tested on this distribution. It would be very useful, for example. for such a lab to participate in functional testing of LAVA upstream.)

  5. Sufficient involvement in the distribution and familiarity with the distribution release process to provide full support for both installing new instances and smoothly upgrading established instances to each new release of the distribution.

    This includes planning ahead to ensure that new dependencies are packaged for the distribution in time for the next distribution release.

  6. Maintenance of LAVA releases within the distribution across more than one distribution release cycle, at the same time.

    This is to ensure that users have continuity of support and can choose when to migrate the base operating system of their labs.

  7. Involvement on IRC and mailing lists to promptly support users experiencing problems with using LAVA on the distribution.

  8. Maintenance of the LAVA documentation covering how to use LAVA on the distribution.

  9. Triage and fixing of issues in LAVA which are specific to the distribution.

  10. Discussion with the rest of LAVA Software Community Project development team around issues related to this distribution.

  11. Use of all available tools within the distribution to anticipate problems. Where possible, implementation of fixes before users are affected.

  12. Maintenance of dependencies using ./share/ to enable automated testing. This includes testing the versions of specific dependencies and ensuring that the minimum version is available in all supported releases of the distribution.

  13. Maintenance of scripts which build Docker images for and using that distribution, including publishing such images. These images will be required to support the internal CI.

  14. Maintenance of upstream LAVA CI using that distribution in Docker to run the unit tests as well as build and test the packaging of LAVA for that distribution. This CI will involve, at a minimum, running such tests on the currently supported distribution release and the candidate for the next distribution release.

  15. Maintenance of upstream CI using gitlab-runner on a machine running the relevant distribution so that CI jobs on the new distribution run in parallel to the CI jobs running on Debian.

  16. Maintenance of LAVA tools and support scripts for running a LAVA lab using the distribution.

  17. Consideration that support for the distribution may involve supporting more than one system architecture.

As an example from LAVA’s history, support for migrations between releases was the main problem for LAVA support of Ubuntu. It became impossible to provide a smooth upgrade path from one Ubuntu LTS release (14.04 Trusty) to the next LTS release (16.04 Xenial). LAVA needs to provide long term stability to provide reliable CI whilst keeping up with changes across supported distributions and tools. For the sake of lab admin workload, support needs to concentrate on LTS or server level releases rather than developer releases or interim updates. Even though Ubuntu is closely related to Debian, the timing of Ubuntu releases made it very difficult to manage complex transitions like the change from Django 1.4 to 1.8 and this was also a concern for the transition to Python3.

You may find that more than one person will be required to meet all these criteria and to maintain that support across several releases of the distribution. The current LAVA Software Community Project team does not have enough resources to do this work for any distribution other than Debian.

Talk to us before spending time on such work.

Preparing for LAVA development

LAVA provides a lava-dev package which supplies all the dependencies which are required to build local LAVA packages. This package is intended primarily for developers working on laptops and other systems where a full desktop environment is already installed:

$ sudo apt install lava-dev

If you want to build local packages on a headless box or a system with limited space, you can trim the set of dependencies by pre-installing pinentry-curses instead of the default pinentry-gtk2. QEMU is still required and will bring in some X11 dependencies but these are minimal compared to the full dependencies of pinentry-gtk2 which is brought in via gnupg2:

$ sudo apt install pinentry-curses
$ sudo apt-get --purge remove pinentry-gtk2
$ sudo apt-get --purge autoremove
$ sudo apt install lava-dev

Developer package build


The supported suite for LAVA development is now Buster. The developer package build now defaults to expecting Buster and therefore uses Python3 exclusively. Support for building Python2 has been removed, the master branch only builds Python3. See

The lava-dev package includes a helper script which is also present in the source code in lava-server/share/. The script requires a normal Debian package build environment (i.e. dpkg-dev), the git-buildpackage helper and the build-dependencies of the package itself. The helper checks for package dependencies using dpkg-checkbuilddeps which halts upon failure with a message showing which packages need to be installed.

Changes from 2018.10 onwards

  • the Debian packaging files are now included upstream, so merge requests can include changes to the packaging directly. The helper script converts the package to a “native” package to allow for unreleased changes.

  • ALL local changes must be committed to a local branch before attempting a build - the helper will fail with an error if git ls-files -m -o --exclude-standard reports any output.

  • Builds are executed in a temporary scratch branch called lavadevscratch which is based on the current local branch and which is deleted at the end of the operation. This is required so that the packaging can be temporarily switched to a developer build.

  • The helper script no longer accepts the -p option, the name of the package is determined from the upstream Debian packaging.

  • The helper script not longer accepts the -b option to change the packaging branch as the packaging is now part of the same branch as the build.

$ /usr/share/lava-server/

From time to time, dependencies may need to vary between the current Debian stable release and the unstable suite and the package building tools expect to build for unstable. If you are building a package to update an instance running a different suite, pass that suite using the -s option:

$ ./share/ -s buster

By default, the packages will be built in the ../build-area/ directory, this can be changed with the -o option. Packages are build using a version string based on the output of ./lava_common/, except that hyphens - are replaced with period . to comply with the rules for a native Debian package. The helper script outputs the relative location of all the files generated by the build at the end of a successful build, ready for use with $ sudo dpkg -i <path_to_dot_deb_file>, repeated for every file or $ sudo debi -u <path_to_lava_dot_changes_file> which will upgrade matching packages which are already installed but skip ones which are not installed. e.g.:

$ sudo dpkg -i ../build-area/lava-common_2018.7-15-g64824c402-1_all.deb
$ sudo dpkg -i ../build-area/lava-dispatcher_2018.7-15-g64824c402-1_amd64.deb

or all in one command:

$ sudo debi -u ../build-area/lava_2018.7-15-g64824c402-1_amd64.changes

To install any package, including the developer build packages, the corresponding package must already be installed at the current production release version (or better), on the same machine. This ensures that all of the runtime dependencies already exist on the system.

Which branch to use for changes

Any and all changes for inclusion into a future release need to be based on the current git master branch and will need rebasing from time to time as master moves ahead.

All testing of the LAVA source code is based on the relevant master branch which is then merged into the staging branch for testing as a release candidate. The final release involves merging staging into the release branch. Git tags are based on the release branch.

When using existing git tags or the release branch, create a new local branch and commit your changes to ensure that a local version string is used.

There can also be new dependencies added by changes in master and staging before those changes are merged into release or uploaded as a production release. When these changes are merged into master, the packaging will also be updated.

Local version strings

The local version is built (using ./lava_common/ from these components:

  • package name

  • git describe - (dashes replaced by dots):

    $ ./lava_common/

The latest git hash is a reference to the latest commit. If you have not committed local changes (e.g. you are on a local branch based on a tag) then the short hash can be used to lookup the commit in the master branch, omitting the g prefix, e.g.:

Distribution differences

Always build packages on the suite you expect to use for installation.

Packages available from the LAVA repositories are built on the correct suite (using sbuild) using the lava-buildd scripts.


The helper supports lava:

$ sudo apt install lava-dev
$ git clone
$ cd lava
$ ./share/

lava-dispatcher has architecture-dependent dependencies. By default, the package is built for the native architecture and can only be installed on that architecture. To build for a different architecture, e.g. arm64, use:

$ /usr/share/lava-server/ -a arm64 -B

This does a binary build, so the source is not included, which allows these builds to be included in a local repository, e.g. using reprepro.

Helpers for other distributions may be added in due course. Patches welcome.

Developer build versions

LAVA uses git tags and the developer build adds a suffix to the tag for each local build - the suffix is formed from the output of git describe

See also

Local version strings for information on how to look up the commit information from the version string.

From August 2015, LAVA uses git tags without a leading zero on the month number, in accordance with PEP440, so the git tag will be 2015.8 instead of 2015.07 used for the previous release tag.

Development using Python3

LAVA has moved to exclusive Python3 support as the final stage of the migration to V2. See

Both lava-server and lava-dispatcher only support running the unit tests with Python3. All reviews must pass the unit tests when run with Python3.

Builds for Debian Jessie have ceased, support for Python2 has been dropped and only Python3 is be supported.

Python3 and other dependencies are tracked using files in share/requirements using the ./share/ script. Required arguments are:

-d, --distribution    Name of a distribution directory in ./share/requirements
-s, --suite           Name of a suite in the specified distribution directory
-p, --package         A LAVA package name in the distribution and suite

Optional arguments are:

-n, --names           List the distribution package names
-u, --unittests       Distribution package names for unittest support -
                      requires --names
./share/ --distribution debian --suite buster --package lava-dispatcher --names
python3-configobj python3-guestfs python3-jinja2 python3-magic
python3-netifaces python3-pexpect python3-pyudev
python3-requests python3-setproctitle python3-tz python3-yaml

Quick fixes and testing

The paths to execute LAVA python scripts and run unit tests have changed and developing LAVA based on packages has a different workflow.

Modified files can be copied to the equivalent python path. The current LAVA packages use python3, so the path is beneath /usr/lib/python3/dist-packages/ with sudo:

$ sudo cp <git-path> /usr/lib/python3/dist-packages/<git-path>

Viewing changes

Different actions are needed for local changes to take effect, depending on the type of file(s) updated:


next browser refresh (F5/Ctrl-R)


next testjob submission


next testjob submission


$ sudo apache2ctl restart

Migrating postgresql versions

LAVA installs the postgresql package which installs the current default version of postgresql. When this default changes in Debian, a second package will be added to your system which will start with no actual data.


postgresql will disable database access during the migration and this will interfere with the running instance. There is typically no rush to do the migration, so this is usually a task for a scheduled maintenance window. Declare a time when all devices can be taken offline and put a replacement site in place of the apache configuration to prevent database access during the migration.

Determining the active cluster

The output of pg_lsclusters includes the port number of each cluster. To ensure that the correct cluster is upgraded, check the LAVA_DB_PORT setting in /etc/lava-server/instance.conf for the current instance. If multiple clusters are shown, postgresql will upgrade to the latest version, so ensure that any intermediate clusters are also stopped before starting the migration.

Performing the migration

Debian gives a notice similar to this when a new version of postgres is installed:

Default clusters and upgrading
When installing a postgresql-X.Y package from scratch, a default
cluster 'main' will automatically be created. This operation is
equivalent to doing 'pg_createcluster X.Y main --start'.

Due to this default cluster, an immediate attempt to upgrade an
earlier 'main' cluster to a new version will fail and you need to
remove the newer default cluster first. E. g., if you have
postgresql-8.2 installed and want to upgrade to 8.3, you first install

 apt install postgresql-8.3

Then drop the default 8.3 cluster:

 pg_dropcluster 8.3 main --stop

And then upgrade the 8.2 cluster to 8.3:

 pg_upgradecluster 8.2 main


Upgrading a cluster combines pg_dump and pg_restore (making two copies of the database at one point). Ensure that you have enough available space on the disc, especially with a large database. If pg_upgradecluster is interrupted by the lack of disc space it will not harm the system and full rollback will be applied automatically.

See also

Check your existing clusters:

$ sudo pg_lsclusters

Stop postgresql (stops both versions):

$ sudo service postgresql stop

Drop the main cluster of the NEW postgres as this is empty:

$ sudo pg_dropcluster 9.4 main --stop

Postgresql knows which version is the current default, so just tell postgresql which is the old version to migrate the data into the (empty) new one:

$ sudo pg_upgradecluster 9.3 main
Disabling connections to the old cluster during upgrade...
Restarting old cluster with restricted connections...
Creating new cluster 9.4/main ...
 config /etc/postgresql/9.4/main
 data   /var/lib/postgresql/9.4/main
 locale en_GB.UTF-8
 port   5433
Disabling connections to the new cluster during upgrade...
Roles, databases, schemas, ACLs...
Fixing hardcoded library paths for stored procedures...
Upgrading database postgres...
Analyzing database postgres...
Fixing hardcoded library paths for stored procedures...
Upgrading database lavaserver...
Analyzing database lavaserver...
Fixing hardcoded library paths for stored procedures...
Upgrading database devel...
Analyzing database devel...
Fixing hardcoded library paths for stored procedures...
Upgrading database template1...
Analyzing database template1...
Re-enabling connections to the old cluster...
Re-enabling connections to the new cluster...
Copying old configuration files...
Copying old start.conf...
Copying old pg_ctl.conf...
Stopping target cluster...
Stopping old cluster...
Disabling automatic startup of old cluster...
Configuring old cluster to use a different port (5433)...
Starting target cluster on the original port...
Success. Please check that the upgraded cluster works. If it does,
you can remove the old cluster with

 pg_dropcluster 9.3 main

Check that the instance is still running. Note that the port of the new postgresql server will have been upgraded to the port used for the old postgresql server automatically. Check that this is the case:

$ grep port /etc/postgresql/9.4/main/postgresql.conf
port = 5432

Drop the old cluster:

$ sudo pg_dropcluster 9.3 main

Now the old database package can be removed:

$ sudo apt remove postgresql-9.3

Dependency Requirements

LAVA needs to control and output the list of dependencies in a variety of formats. Building Docker images and running unit tests in an LXC need an updated list of binary package names suitable for the distribution and suite of the LXC. Each needs to cope with dependencies outside the specified suite, e.g. stable releases which need backports. Building the LAVA Debian packages themselves also requires a properly up to date list of dependencies - including minimum versions. Each set of dependencies needs to be specific to each LAVA binary package - lava-server has different dependencies to lava-dispatcher and lava-common.

LAVA has several dependencies which are not available via PyPi or pip and the requirements.txt file is therefore misleading. However, the format of this file is still useful in building the LAVA packages.

Therefore, LAVA has the ./share/ script which can be used to output the preferred format, depending on the arguments. The script is also included in the lava-dev package as /usr/share/lava-server/

The dependencies MUST be installed in the specified release of the specified distribution for LAVA to work, so take care before pushing a merge request to add package names to the support. Make sure your merge request includes a change to the relevant requirement YAML files for all supported distributions or the CI will fail.

Some distributions support Recommends level dependencies. These are typically intended to be installed by ~90% of installations but give flexibility for other use cases. Recommends are not handled by at all. The packages must be listed explicitly by the maintainer of the packaging for the distribution. exists so that automated processes, like CI, can have a reliable but minimal set of packages which must be installed for the specified package to be installable. To use a minimal installation, each package listed by ./share/` can be installed without its recommended packages using the apt install --no-install-recommends <packages> syntax. does not currently support dependencies based on the architecture of the installation. (Currently, only Recommends includes architecture-sensitive packages.)

Outputting the requirements.txt format

Processes which need the version string can use the original output format which mimics requirements.txt:

$ ./share/ --package lava-server --distribution debian --suite buster

Outputting a list of binary package names

This is intended to be passed directly to a package installer like apt-get together with the other required commands and options.

The caller determines the suite, so to use with buster-backports, the -t buster-backports option would also be added to the other apt-get commands before appending the list of packages.

(Line breaks are added for readability only):

$ ./share/ --package lava-server --distribution debian --suite buster --names
python3-django python3-yaml python3-docutils \
python3-jinja2 python3-psycopg2 python3-tz python3-zmq python3-requests \

Adding packages needed for the unittests

Some packages are only required to allow the unittests to pass. To add these packages, use the --unittest option, in combination with --names. These packages need to be added to the installation as well as the base list of packages using --names.

$ ./share/ --package lava-server --distribution debian --suite unstable --names --unittest
python3-pytest-django python3-pytest python3-pytest-cov
$ ./share/ --package lava-dispatcher --distribution debian --suite unstable --names --unittest
pyocd-flashtool gdb-multiarch git schroot lxc img2simg simg2img u-boot-tools xnbd-server telnet qemu-system-x86 qemu-system-arm

Javascript handling

Javascript has particular issues in distributions, often the version of a Javascript file is out of step with the version available in the distribution or not packaged at all. lava-server embeds javascript files in the static/js directories and maintains a list of files which are replaced with symlinks during a Debian package build. The list is in share/javascript.yaml and the replacement of matching files is done using share/ Other distribution builds are invited to use the same script or provide patches if the paths within the script need modification.

After 2015.12 release, all of the .min.js files in the package are removed from VCS and minified files are created at build time. Templates in the system use only minified versions of the javascript files so after the release package rebuild will be mandatory.

Javascript and security

The primary concern is security fixes. Distributions release with a particular release of LAVA and may need to fix security problems in that release. If the file is replaced by a symlink to an external package in the distribution, then the security problem and fix migrate to that package. LAVA tracks these files in share/javascript.yaml. Files which only exist in LAVA or exist at a different version to the one available in the distribution, need to be patched within LAVA. Javascript files created by LAVA are packaged as editable source code and patches to these files will take effect in LAVA after a simple restart of apache and a clearing of any browser cache. Problems arise when the javascript files in the LAVA source code have been minified, resulting in a .min.js file which is not suitable for editing or patching.

The source code for the minified JS used in LAVA is provided in the LAVA source code, alongside the minified version. However, there is a lack of suitable tools to convert changes to the source file into a comparable minified file. If these files need changes, the correct fix would be to patch the unminified javascript and copy the modified file over the top of the minified version. This loses the advantages of minification but gains the benefit of a known security fix.

Javascript maintenance

Work is ongoing upstream to resolve the remaining minified javascript files:

  1. Identify the upstream location of all javascript not listed in share/javascript.yaml and not written by LAVA, specify this location in a README in the relevant js/ directory along with details, if any, of how a modified file can be minified or whether a modified file should simply replace the minified file.

  2. Replace the use of the remaining minified JS where the change to unminified has a negligible or acceptable performance change. If no upstream can be identified, LAVA will need to take over maintenance of the javascript itself, at which point minified files will be dropped until other LAVA javascript can also be minified.

  3. Monitor availability of packages for all javascript files not written by LAVA and add to the listing in share/javascript.yaml when packages become available.

  4. Maintain - only minify javascript written by LAVA if a suitable minify tool is available to be used during the build of the packages and to add such support to share/ so that minification happens at the same point as replacement of embedded javascript with symlinks to externally provided files.

Packaging changes

From time to time, there can be packaging changes required to handle changes in the LAVA upstream codebase. If you have write access to the packaging repository, changes to the packaging can be tested by pushing to your fork of lava.git and making a local commit. Then build as normal:

$ /usr/share/lava-server/

Building for other architectures

lava-server is the same for all architectures but lava-dispatcher has a different set of dependencies depending on the build architecture. To build an arm64 package of lava-dispatcher using the developer scripts, use:

$ /usr/share/lava-server/ -a arm64 -B

Debugging Django issues

When trying to investigate LAVA web pages generation we advise you to use django-debug-toolbar. This is a Django application that provide more information on how the page was rendered, including:

  • SQL queries

  • templates involved

  • HTTP headers

For instance, the toolbar is a really helpful resource to debug the Django ORM.


On a Debian system, just run:

$ apt-get install python-django-debug-toolbar


Once the python-django-debug-toolbar package is installed, the toolbar needs to be enabled in the instance. Two settings are required in /etc/lava-server/settings.conf

  • "DEBUG": true,

  • "USE_DEBUG_TOOLBAR": true,


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 toolbar can be disabled without disabling django debug but django must be in debug mode for the toolbar to be loaded at all.

Restart the django related services to complete the installation of the toolbar:

sudo service lava-server-gunicorn restart
sudo apache2ctl restart

Installation can be checked using lava-server manage shell:

>>> from django.conf import settings
>>> 'debug_toolbar' in settings.INSTALLED_APPS

In order to see the toolbar, you should also check the value of INTERNAL_IPS. Local addresses and ::1 are enabled by default.

To add more addresses, set INTERNAL_IPS to a list of addresses in /etc/lava-server/settings.conf, (JSON syntax) for example:

"INTERNAL_IPS": ["", ""],

These value depends on your setup. But if you don’t see the toolbar that’s the first think to look at.

Apache then needs access to django-debug-toolbar CSS and JS files:

sudo su -
cd /usr/share/lava-server/static/
ln -s /usr/lib/python3/dist-packages/debug_toolbar/static/debug_toolbar .

In /etc/lava-server/settings.conf remove the reference to htdocs in STATICFILES_DIRS. Django-debug-toolbar does check that all directories listed in STATICFILES_DIRS exists. While this is only a leftover from previous versions of LAVA installer that is not needed anymore.

Once the changes are complete, ensure the settings are loaded by restarting both apache2 and django:

sudo service lava-server-gunicorn restart
sudo apache2ctl restart

Performance overhead

Keep in mind that django-debug-toolbar has some overhead on the web page generation and should only be used while debugging.

Django-debug-toolbar can be disabled, while not debugging, by changing the value of USE_DEBUG_TOOLBAR in /etc/lava-server/settings.conf to false or by changing the ̀DEBUG level in /etc/lava-server/settings.conf to DEBUG: false.

Ensure the settings are reloaded by restarting both apache2 and django:

sudo service lava-server-gunicorn restart
sudo apache2ctl restart