Advanced Installation Topics

The basic installation guide should be a good start for most users installing LAVA. For more advanced users, here is much more information and recommendations for administrators.

Requirements to Consider Before Installing LAVA


Be careful with laptop installations, particularly if you are using health checks. It is all too easy for a health check to take the device offline just because the laptop was suspended or without an internet connection at the relevant moment.

Laptops also have limitations on device availability but are routinely used as development platforms and can support QEMU devices without problems.

Virtual Machines

LAVA installations inside a virtual machine (or container) have particular constraints. A QEMU device or container may suffer from being executed within the constraints of the existing virtualisation and other devices may need USB device nodes to be passed through to the VM. Depending on the VM, it is also possible that storage space for the logs may become an issue.


Consider the expected load on the master and each of the workers:

  • The workload on the master primarily depends on:
    1. the visibility of the instance,
    2. the number of users,
    3. the average number of jobs in the queue and
    4. the total number of devices attached across all the workers connected to this master.
  • The workload on the worker involves a range of tasks, scaling with the number of devices attached to the worker:
    1. doing a lot of synchronous I/O,
    2. decompression of large files
    3. serving large files over TFTP or HTTP and
    4. git clone operations.

An ARMv7 device can serve as a small master or worker, but SATA support is strongly recommended along with at least 2GB of RAM.


LAVA expects to be the primary virtual host configured on the master. This has improved with V2 but unless your instance is V2-only, you may experience problems or require additional configuration to use LAVA as a virtual host.

Other infrastructure

LAVA will need other services to be available, either using separate tools on the same machines or as separate hardware. This list is not exhaustive.

Remote power control

Automated power control using a PDU is one of the most common issues to be solved when setting up a new LAVA lab. Hardware can be difficult to obtain and configuring the remote power control can require custom scripting. There is no single perfect device for all use cases, and a wide variety of possible solutions may exist to cover your needs. Take the time to research the issues and ask on the lava-users mailing list if you need guidance.

Serial console support

Once more than a handful of devices are attached to a worker it will often become necessary to have a separate unit to handle the serial connectivity, turning serial ports into TCP ports. Bespoke serial console servers can be expensive; alternatives include ARMv7 boards with ser2net installed but the USB and ethernet support needs to be reliable for this to work well.

Network switches

Simple unmanaged switches will work for small LAVA labs but managed switches are essential to use VLANd support in LAVA test jobs and will also be important for medium to large LAVA labs.

Power supply

Use of a UPS will allow the entire lab to cope with power interruptions. Depending on the budget, this could be a small UPS capable of supporting the master and the worker for 10 minutes, or it could be a combination of larger UPS units and a generator.


The master is not the correct place to be building or storing build artefacts. In a busy lab, the extra load may cause issues when workers download large files at job startup. Development builds and creation of files to support the LAVA test should happen on a suitably powerful machine to meet the performance expectations of the CI loop and the developers.

Shelving and racks

While it may be tempting to set up a lab on a desk or test bench, this can very quickly degenerate into a tangled mess as more devices are added. On top of the test devices, switches and other infrastructure, there will be a lot of power cables, network cables and serial cables. For even a small lab of a handful of devices, a set of shelves or a wall-mounted rack is going to make things a lot easier to manage.

Other installation notes

Automated installation

Using debconf pre-seeding with Debian packages

Debconf is the standard method on Debian systems for controlling and storing high-level configuration for packages. Debian packages may ask questions during installation to set up this configuration. Debconf may also be automated, using a text file which contains the answers to those debconf questions - just keep the file up to date if the questions change. For example, to preseed a worker install:

$ cat preseed.txt
lava-server   lava-worker/db-port string 5432
lava-server   lava-worker/db-user string lava-server
lava-server   lava-server/master boolean false
lava-server   lava-worker/master-instance-name string default
lava-server   lava-worker/db-server string snagglepuss.codehelp
lava-server   lava-worker/db-pass string werewolves
lava-server   lava-worker/db-name string lava-server

To insert the preseed information into the debconf database:

$ sudo debconf-set-selections < preseed.txt

or to show the existing debconf information for a package:

$ sudo debconf-show lava-server
* lava-worker/master-instance-name: default
* lava-server/master: false
* lava-worker/db-pass: werewolves
* lava-worker/db-port: 5432
* lava-worker/db-name: lava-server
* lava-worker/db-server: snagglepuss.codehelp
* lava-worker/db-user: lava-server

The strings available for seeding are in the Debian packaging for the relevant package, in the debian/<PACKAGE>.templates file.

LAVA server branding support

The icon, link, alt text, bug URL and source code URL of the LAVA link on each page can be changed in the settings /etc/lava-server/settings.conf (JSON syntax):

"BRANDING_ALT": "Example site",

Admins can include a sentence describing the purpose of the instance to give more detail than is available via the instance name. This will be added in a paragraph on the home page under “About the {{instance_name}} LAVA instance”:

"BRANDING_MESSAGE": "Example site for local testing",

If the icon is available under the django static files location, this location can be specified instead of a URL:

"BRANDING_ICON": "path/to/image.png",

There are limits to the size of the image, approximately 32x32 pixels, to avoid overlap.

The favicon is configurable via the Apache configuration:

Alias /favicon.ico /usr/share/lava-server/static/lava-server/images/logo.png

Unattended upgrades

Debian provides a package called unattended-upgrades which can be installed to automatically install security (and other) updates on Debian systems. This service is recommended for LAVA instances, but is not part of LAVA itself.

If you plan to use unattended-upgrades, it is a good idea to set up monitoring on your systems, for example by also installing apt-listchanges and configuring email for administrator use. Ensure that the master and all workers are similarly configured, to avoid potential problems with skew in package versions.

Example changes


The default installation of unattended-upgrades enables automatic upgrades for all security updates:

Unattended-Upgrade::Origins-Pattern {


Optionally add automatic updates from the LAVA repositories if those are in use:

Unattended-Upgrade::Origins-Pattern {


Other repositories can be added to the upgrade by checking the output of apt-cache policy, e.g.:

release v=8.1,o=Linaro,a=unstable,n=sid,l=Lava,c=main

Relates to an origin (o) of Linaro and a label (l) of Lava.

When configuring unattended upgrades for the master or any worker which still supports LAVA V1, PostgreSQL will need to be added to the Package-Blacklist. Although services like PostgreSQL do get security updates and these updates are important to apply, unattended-upgrades does not currently restart other services which are dependent on the service being upgraded. Admins still need to watch for security updates to PostgreSQL and apply the update manually, restarting services like lavapdu-runner, lava-master, lava-server and vland afterwards:

Unattended-Upgrade::Package-Blacklist {

Email notifications also need to be configured.

Unattended-Upgrade::Mail "";

Unattended-Upgrade::MailOnlyOnError "true";

With these changes to /etc/apt/apt.conf.d/50unattended-upgrades, the rest of the setup is as described on the Debian wiki.

Configuring event notifications

Event notifications must be configured before being enabled.

  • All changes need to be configured in /etc/lava-server/settings.conf (JSON syntax).
  • Ensure that the EVENT_TOPIC is changed to a string which the receivers of the events can use for filtering.
    • Instances in the Cambridge lab use a convention which is similar to that used by DBus or Java, simply reversing the domain name for the instance (e.g. org.linaro.validation)
  • Ensure that the EVENT_SOCKET is visible to the receivers - change the default port of 5500 if required.
  • Enable event notifications by setting EVENT_NOTIFICATION to true

When changing the configuration, you should restart the corresponding services:

$ sudo service lava-publisher restart
$ sudo service lava-master restart
$ sudo service lava-server restart
$ sudo service lava-server-gunicorn restart

The default values for the event notification settings are:

"EVENT_TOPIC": "org.linaro.validation",
"INTERNAL_EVENT_SOCKET": "ipc:///tmp/",
"EVENT_SOCKET": "tcp://*:5500",

The INTERNAL_EVENT_SOCKET does not usually need to be changed.

Services which will receive these events must be able to connect to the EVENT_SOCKET. Depending on your local configuration, this may involve opening the specified port on a firewall.

Events and network reliability

With the default configuration, LAVA will publish events to the EVENT_SOCKET only, using a zmq PUB socket. This type of socket is efficient for publishing messages to a large audience. However, in case of a network breakage, the connection may be lost and events may be missed.

For more reliable event publication on an unreliable network (like the Internet) with a small set of known listeners, you can also use EVENT_ADDITIONAL_SOCKETS. The publisher will connect to each of the endpoints in this list using a zmq PUSH socket. These sockets are configured to keep a large queue of messages for each of the endpoints, and will retry to deliver those messages as necessary. No messages will be lost until the queue overflows.

LAVA server performances

If the load on the master becomes an issue, there may be some optimisations which can help.

The default settings should work out of the box. This might not be the case for some optimisations that should be tested carefully.


The different assets (CSS, js, images, etc.) are already handled directly by apache but without any caching.

To add browser caching, update the apache2 configuration to add Expires header for every static assets.

<location /static>
  ExpiresActive On
  ExpiresDefault "access plus 1 month"


For the complete documentation see the apache documentation

Template caching

Django does also provide a way to store in memory the compiled version of the templates using the cached loader.

To enable the cached loader, in /etc/lava-server/settings.conf add:


You should then restart lava-server-gunicorn.

$ sudo service lava-server-gunicorn restart