First steps installing LAVA

Initial LAVA Installation

The default installation provides an Apache2 config suitable for a simple LAVA server at http://localhost/ once enabled.

See Packaging lava-server for distributions for more information or for debugging.

Requirements to Consider Before Installing LAVA


A LAVA instance consists of two primary components - a server and a worker. The simplest possible configuration is to run the master and worker components on a single machine, but a larger instance can also be configured to support multiple workers controlling a larger number of attached devices.

Elements of the Master

  • Web interface - This is built using the Apache web server, the uWSGI application server and the Django web framework. It also provides XML-RPC access and the REST API.

  • Database - This uses PostgreSQL locally on the master, with no external access.

  • Scheduler - This is the piece that causes jobs to be run - periodically this will scan the database to check for queued test jobs and available test devices, starting jobs when the needed resources become available.

  • lava-server-gunicorn daemon - This communicates with the worker(s) using HTTP

Elements of the Worker

  • lava-worker daemon - This receives control messages from the server.

  • Dispatcher - This manages all the operations on the device under test, according to the job submission and device parameters sent by the master.

  • Device Under Test (DUT)


Although the Dispatcher interacts directly with the DUT, all the device configuration is sent from the server.

Software Requirements


LAVA is developed using Debian packaging to ensure that daemons and system-wide configuration is correctly updated with changes in the codebase. There is no official support for pypi or python virtual environments or installing directly from a git directory. See Installing on a Debian system for detailed instructions.

We currently recommend installing LAVA on Debian buster or unstable.

LAVA software has now moved to Python3 support. This also means that Jessie is no longer supported.

Contributions to support other distributions are welcome.

If you’d like to help us provide support for other distributions, feel free to contact us using the lava-devel mailing list.

Hardware Requirements

A small LAVA instance can be deployed on fairly modest hardware. We recommend at least 1GB of RAM to cover the runtime needs of the database server, the application server and the web server. For storage, reserve about 20GB for application data, especially if you wish to mirror the current public Linaro LAVA instance. LAVA uses append-only models, so storage requirements will grow over time.

If you are deploying many devices and expect to be running large numbers of jobs, you will obviously need more RAM and disk space.

Device requirements

Devices you wish to deploy in LAVA need to be:

  • Physically connected to the server via usb, usb-serial, or serial; or

  • connected over the network via a serial console server; or

  • a fastboot capable device accessible from the server; or

  • a virtual machine or simulator that emulates a serial connection

MultiNode hardware requirements

If the instance is going to be sent any job submissions from third parties or if your own job submissions are going to use MultiNode, there are additional considerations for hardware requirements.

MultiNode is explicitly designed to synchronize test operations across multiple test devices and running MultiNode jobs on a particular instance will have implications for the workload of that instance. This can become a particular problem if the instance is running on virtualized hardware with shared I/O, a limited amount of RAM or a limited number of available cores.


Downloading, preparing and deploying test images can result in a lot of synchronous I/O and if a single machine is running both the LAVA server and dispatcher, running synchronized MultiNode jobs can cause the load on that machine to rise significantly, possibly causing the server to become unresponsive. For this reason, it is strongly recommended that MultiNode instances use a separate dispatcher running on non-virtualized hardware so that the (possibly virtualized) server can continue to operate.

Also, consider the number of test devices connected to any one dispatcher. MultiNode jobs will commonly compress and decompress several large test image files in parallel. Even with a powerful multi-core machine, this can cause high load. It is worth considering matching the number of devices to the number of cores for parallel decompression, and matching the amount of available RAM to the number and size of test images which are likely to be in use.

Which release to install

The LAVA team makes regular releases (called production releases), typically monthly. These are installed onto Linaro’s central instance and they are also uploaded to Debian unstable and backports (see Installing on a Debian system). These production releases using tags on the master branch.

Interim releases are made available from the daily builds.

If in doubt, install the production release of lava-server from official distribution mirrors. (Backports are included on Debian mirrors.)

The lava-dev package includes scripts to assist in local developer builds directly from local git working copies which allows for builds using unreleased code, development code and patches under review.

Installation Types

Single Master Instance installation

A single instance runs the web interface, the database, the scheduler and the dispatcher on a single machine. If this machine is also running tests, the device (or devices) under test (DUT) will also need to be connected to this machine, possibly over the network, using USB or using serial cables.

To install a single master instance and create a superuser, refer to Installing on a Debian system installation.

LAVA V1 used to support a distributed_instance installation method. This has been removed in V2; instead there is a much improved architecture for remote workers using HTTP.

Detailed instructions for setting up workers follows - first, think about the kind of configuration needed for your instance.

Master with one or more workers

You can choose whether the master has devices configured locally or only uses devices via one or more remote workers. If you are installing and learning how to use LAVA for the first time, it is recommended to keep things simple and stick to a Single Master Instance installation to start with.

Configuration outline - start simple…

  • Configure the master as a Single Master Instance installation. It will need the lava-server and lava-dispatcher packages installed.

  • Use the Django administrative interface or command line tools to define the device types likely to be used with this instance.

  • Prepare Device Dictionaries for your devices.

  • Run some health check tests and see how things work.

…then expand

Once you are happy with your basic single-machine installation and are ready to expand beyond that, start adding workers one at a time. For this configuration:

As you expand your setup, you will also need to do some configuration of communications between the master and the worker(s), which rely on HTTP as an underlying technology. Workers on the same (trusted) network as the master can work fine without using authentication and encryption, but if you are going to be hosting workers on a remote network then it is strongly recommended to use HTTPS to communicate with the server

  • On your new worker, configure lava-worker to look for the server

  • On the master, use the Django administration interface to add details of the new worker to the database.

  • On the master, configure the Device Dictionaries for all the devices attached to the new worker.

  • Assign devices to the new worker.

  • Run health checks and be sure that all the devices on the new worker are properly configured and working.

  • Repeat for additional workers as needed.

LAVA Coordinator setup

If you are expecting to support MultiNode jobs in your LAVA setup, there is a third component needed. The LAVA Coordinator manages the extra message passing needed between the various nodes in a MultiNode group of devices. Nodes connect to the LAVA Coordinator daemon via TCP (default port: 3079). A single coordinator can manage groups from multiple instances if desired. If the network configuration uses a firewall, ensure that this port is open for connections from MultiNode dispatchers.

If multiple coordinators are necessary on a single machine (e.g. to test different versions of the coordinator during development), each coordinator needs to be configured for a different port.

If the dispatcher is installed on the same machine as the coordinator, the dispatcher can use the packaged configuration file with the default hostname of localhost.

Each dispatcher then needs a copy of the LAVA Coordinator configuration file (JSON syntax), modified to point back to the hostname of the coordinator:

Example JSON, modified for a coordinator on a machine with a fully qualified domain name:

  "port": 3079,
  "blocksize": 4096,
  "poll_delay": 3,
  "coordinator_hostname": ""

An IP address can be specified instead, if appropriate.

Each dispatcher needs to use the same port number and blocksize as is configured for the Coordinator on the specified machine. The poll_delay is the number of seconds each node will wait before polling the coordinator again.

Setting Up Serial Connections to LAVA Devices

LAVA controls the DUT using a serial connection, except for emulated devices like QEMU.

LAVA can support multiple serial connections per DUT. The recommended method for creating a serial connection is to use Ser2net daemon to provide a connection using the telnet client. This allows simple and clean disconnection and allows LAVA to use the connection over the network. Other tools (conmux, minicom) have been tried but showed reliability problems when used at scale. LAVA is not able to directly access a device node.

See also

Growing your lab and Serial console support for information about hardware.

ser2net is the recommendation based on several million test jobs.

See also

Serial console support for information about hardware.


Make sure your serial connection configuration is backed up as it can be an awkward process to manually establish which path in /dev/serial/by-id is which cable and therefore connected to which device.

Ser2net daemon

ser2net provides a way for a user to connect from a network connection to a serial port, usually over telnet.

ser2net is a dependency of lava-dispatcher, so will be installed automatically.

Example config (in /etc/ser2net.conf):

#port:connectiontype:idle_timeout:serial_device:baudrate databit parity stopbit
7001:telnet:0:/dev/serial/by-id/serial_path:115200 8DATABITS NONE 1STOPBIT LOCAL


In the above example we have the idle_timeout as 0 which specifies a infinite idle_timeout value. 0 is the recommended value. If the user prefers to give a positive finite idle_timeout value, then there is a possibility that long running jobs may terminate due to inactivity on the serial connection.

Always use paths in /dev/serial/by-id/ in the configuration to prevent connections being lost when devices reenumerate.

The LOCAL flag is necessary if you connect modem control lines (for example a full RS232 cable) to prevent connection aborts on DUT power cycling.

StarTech rackmount usb

  • udev rules:

    SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="ST167570", SYMLINK+="rack-usb02"
    SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="ST167569", SYMLINK+="rack-usb01"
    SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="ST167572", SYMLINK+="rack-usb04"
    SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="ST167571", SYMLINK+="rack-usb03"

This will create a symlink in /dev called rack-usb01 etc. which can then be addressed in the Ser2net daemon config file.

Contact and bug reports

Please report bugs using the LAVA Users mailing list:

You can also report bugs using reportbug and the Debian Bug Tracking System:

Feel free to contact us at validation (at) linaro (dot) org and on the #linaro-lava channel on OFTC but note that IRC is not well suited to some discussions. Problems with device configuration or test job failures usually benefit from being able to attach the full configuration to an email to the lava-users mailing list.