.. index:: advanced installation topics, laptop, virtual machine

.. _advanced_installation:

Advanced Installation Topics
############################

The :ref:`basic installation guide <installation>` 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
***********************************************

.. _laptop_requirements:

Laptops
=======

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_machine_requirements:

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 virtualization
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.

.. _workload_requirements:

Workload
========

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

* The workload on the **master** primarily depends on:

  #. the visibility of the instance,
  #. the number of users,
  #. the average number of jobs in the queue and
  #. 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:

  #. doing a lot of synchronous I/O,
  #. decompression of large files
  #. serving large files over TFTP or HTTP and
  #. 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.

Localhost
=========

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.

.. index:: infrastructure requirements

.. _infrastructure_requirements:

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.

.. index:: power control infrastructure, automated power control

.. _power_control_infrastructure:

Remote power control
--------------------

Automated power control using a :abbr:`PDU (Power Distribution Unit)`
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 :ref:`lava_users` mailing list if you need
guidance.

.. index:: serial console support, serial console server

.. _serial_console_support:

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_switch_infrastructure:

Network switches
----------------

Simple unmanaged switches will work for small LAVA labs but managed switches
are essential to use :ref:`vland_in_lava` and will also be important for medium
to large LAVA labs.

.. _power_supply_ups:

Power supply
------------

Use of a :abbr:`UPS (Uninterruptible Power Supply)` 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.

.. _fileserver_infrastructure:

Fileserver
----------

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.

.. _mailserver_infrastructure:

Mailserver
----------

For sending user notifications via email there is additional configuration
to be done. There needs to be a SMTP server or a mail relay set up (which
is out of scope for this document) and LAVA configured to use it.

Create a new YAML configuration file for LAVA like

   /etc/lava-server/settings.d/01-mail.yaml

and put in your configuration there. A minimal configuration will most probably
look like this:

   SERVER_EMAIL: 'lava-noreply@example.net'
   EMAIL_HOST: 'smtp.example.net'

See `django email settings <https://docs.djangoproject.com/en/3.2/ref/settings/#email-host>`__
for a full list of all supported configuration, including TLS and authentication.

Don't forget to reload LAVA webserver to set configuration active:

   $ systemctl reload lava-server-gunicorn.service

.. _more_installation_types:

Recommended Installation Types
******************************

Single instance
===============

The :ref:`basic guide <installation>` shows how to install
``lava-server`` and ``lava-dispatcher`` on a single machine. This kind
of simple instance can be very useful for local development, testing
inside virtual machines and small scale testing.

However, the most obvious limitation of the single-instance
installation is on the number of devices which can be supported. This
normally is controlled by the number of test devices that may be
connected directly to the machine. The solution here is easy: as your
lab grows, keep the original machine as the master. Add one or more
new machines as workers, and move test devices over to those new
workers.

Master with one or more remote workers
======================================

Any single instance of LAVA can be extended to work with one or more workers
which only need the ``lava-dispatcher`` package installed.

Authentication and encryption
-----------------------------

When the worker is on the same trusted network as the master,
administrators may safely choose to connect workers to the server without
authentication. In all other cases, use https to connect to the server.

Other installation notes
************************

.. index:: branding

.. _branding:

LAVA server branding support
============================

The instance name, 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)::

   "INSTANCE_NAME": "default",
   "BRANDING_URL": "http://www.example.org",
   "BRANDING_ALT": "Example site",
   "BRANDING_ICON": "https://www.example.org/logo/logo.png",
   "BRANDING_HEIGHT": 26,
   "BRANDING_WIDTH": 32,
   "BRANDING_BUG_URL": "http://bugs.example.org/lava",
   "BRANDING_SOURCE_URL": "https://github.com/example/lava-server",
   "BRANDING_CSS": "https://www.example.org/css/style.css",

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",
   "INSTANCE_NAME": "dev-box",

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

   "BRANDING_CSS": "path/to/style.css",
   "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

.. index:: security upgrades, unattended upgrades

.. _unattended_upgrades:

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.

.. seealso:: https://wiki.debian.org/UnattendedUpgrades

Example changes
---------------

``/etc/apt/apt.conf.d/50unattended-upgrades``

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

   Unattended-Upgrade::Origins-Pattern {

        "origin=Debian,codename=jessie,label=Debian-Security";
   };


Optionally add automatic updates from the :ref:`lava_repositories` if those are
in use::

   Unattended-Upgrade::Origins-Pattern {

        "origin=Debian,codename=jessie,label=Debian-Security";
        "origin=Linaro,label=Lava";
   };

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 ``lava-master``,
``lava-server`` and ``vland`` afterwards::

   Unattended-Upgrade::Package-Blacklist {
        "postgresql-9.4";
   };

Email notifications also need to be configured.

::

   Unattended-Upgrade::Mail "lava-admins@example.com";

   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.

https://wiki.debian.org/UnattendedUpgrades#Automatic_call_via_.2Fetc.2Fapt.2Fapt.conf.d.2F20auto-upgrades

.. index:: event notifications - configuration

.. _configuring_event_notifications:

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:

.. code-block:: shell

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

The default values for the event notification settings are:

.. code-block:: python

 "EVENT_TOPIC": "org.linaro.validation",
 "INTERNAL_EVENT_SOCKET": "ipc:///tmp/lava.events",
 "EVENT_SOCKET": "tcp://*:5500",
 "EVENT_NOTIFICATION": false,
 "EVENT_ADDITIONAL_SOCKETS": []

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
<http://api.zeromq.org/4-2:zmq-socket#toc7>`__. 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
<http://api.zeromq.org/4-2:zmq-socket#toc12>`__. 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.

.. seealso:: :ref:`publishing_events`

.. index:: postgres configuration

.. _postgres_db_port:

PostgreSQL Port configuration
=============================

In the majority of cases, there is no need to change the PostgreSQL port number
from the default of ``5432``. If a change is required, edit
``/etc/lava-server/instance.conf`` and then restart the LAVA master and UI
daemons:

.. code-block:: none

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

.. _configuring_ui:

Configuring the LAVA UI
***********************

Initial settings for a LAVA instance change over time as the
requirements change and dependencies improve internal security
implementations. Most instances will need some adjustment to the apache
configuration for the main LAVA UI in
``/etc/apache2/sites-available/lava-server.conf`` and LAVA does not
attempt to patch this file once admins have made changes. Admins
therefore need to subscribe to the :ref:`lava_announce` mailing list
and make changes using separate configuration management.

Gunicorn3 bind addresses
========================

Work is beginning to extend the :ref:`Docker support <docker_admin>` to
have different parts of LAVA in different containers. Some parts of
this are easier to implement than others, so the support will arrive in
stages.

``gunicorn3`` supports changing the bind address which will allow to run
the ``lava-server-gunicorn`` service to run alone in a container while
having the reverse proxy in another container. The bind address and
other ``gunicorn3`` options can be changed by editing:
``/etc/lava-server/lava-server-gunicorn``

.. seealso:: http://docs.gunicorn.org/en/stable/settings.html

Apache proxy configuration
==========================

.. seealso:: :ref:`django_localhost`

Django requires the allowed hosts to be explicitly set in the LAVA
settings, as a list of hostnames or IP addresses which LAVA is allowed
to use. If this is wrongly configured, the UI will raise a HTTP500 and
you will get information in the output of ``lava-server manage check
--deploy`` or in ``/var/log/lava-server/django.log``. For example,
``/etc/lava-server/settings.conf`` for https://lava.codehelp.co.uk/
contains:

.. code-block:: none

    "ALLOWED_HOSTS": ["lava.codehelp.co.uk"],

.. seealso:: https://docs.djangoproject.com/en/3.2/ref/settings/#allowed-hosts

It is also important to enable ``ProxyPreserveHost`` in
``/etc/apache2/sites-available/lava-server.conf``:

.. code-block:: none

    ProxyPreserveHost On

In some situations, you may also need to set ``USE_X_FORWARDED_HOST``
to ``True`` in ``/etc/lava-server/settings.conf``

.. seealso:: https://docs.djangoproject.com/en/3.2/ref/settings/#std:setting-USE_X_FORWARDED_HOST

Apache headers
==============

Browser caching can be improved by enabling ``mod_header`` in Apache
to allow LAVA to send appropriate cache control headers as well as
``mod proxy`` and ``mod proxy_http``::

 $ sudo a2enmod header
 $ sudo a2enmod expires
 $ sudo service apache2 restart

.. controlling_bots:

Banning badly behaved bots
==========================

Despite setting ``robots.txt``, LAVA instances can sometimes come under
high load due to badly behaved web crawling bots. Typically, this will
show up as an unusually slow LAVA UI and large apache log files showing
a lot of unusual activity. For example, recursively retrieving every
query string variation for every table or trying to access every
possible URL without being signed in.

To control these bots, the ``DISALLOWED_USER_AGENTS`` setting can be
extended. By default, LAVA blocks ``yandex``, ``SemrushBot``, ``bing``
and ``WOW64``. The list can be extended in
``/etc/lava-server/settings.conf``. If you do extend the list, please
let us know by subscribing to the :ref:`lava_devel` mailing list and
posting your updated list.

.. seealso:: https://docs.djangoproject.com/en/3.2/ref/settings/#std:setting-DISALLOWED_USER_AGENTS


.. _tracking_errors:

Tracking errors
===============

In order to track server errors, admins can enable `sentry <https://sentry.io>`_ error tacking.
In ``/etc/lava-server/settings.conf`` add::

    "SENTRY_DSN": "https://<public_key>@<server>/<project_id>"

When any of the services is crashing, an error will be recorded along with some metadata.

To optionally track performance metrics with Sentry, you can configure "SENTRY_TRACES_SAMPLE_RATE".
This setting controls the percentage of error events that will be sent for performance monitoring,
with a value between 0 (0% of errors) and 1 (100% of errors).

In ``/etc/lava-server/settings.conf`` add::

    "SENTRY_TRACES_SAMPLE_RATE": "1.0"

Configuring default table length
================================

The LAVA UI mainly consists of tables. The length of each table can be
configured by the user right above it ("Show 10..100 entries"). A default
value for the table length can be set in ``/etc/lava-server/settings.conf``:

.. code-block:: python

 "DEFAULT_TABLE_LENGTH": 50,

Configuring submitter full name
================================

The LAVA main job page by default will show user name of submitter.
Admin could set if to show full name of submitter in ``/etc/lava-server/settings.conf``:

.. code-block:: python

 "SHOW_SUBMITTER_FULL_NAME": true,

.. _localisation:

Localisation
============

As LAVA is based on Django framework, localisation is available. To adjust
date and time to local format (including DST adjustment), configure settings
accordingly in a new config file, e.g. ``/etc/lava-server/settings.d/02-l10n.yaml``:

.. code-block:: yaml

    TIME_ZONE: "Europe/Berlin"
    DATETIME_FORMAT: 'Y-m-d H:i:s'

Without this, time will be american format and all times displayed in UTC.

See `django documentation <https://docs.djangoproject.com/en/3.2/ref/settings/#std:setting-TIME_ZONE>`__
for details and a list of possible ``TIME_ZONE`` values.

It is possible to set ``LANGUAGE_CODE`` to another value than the default
``en-us``, but this will only affect administration interface as LAVA does
not support translation to other languages.

Configuring default queue timeout
=================================

The LAVA scheduler by default won't cancel any request pending in the queue, unless
user specify queue timeout in job definition.
Admin could set default queue timeout (Unit: hours) in ``/etc/lava-server/settings.conf`` for
per instance to avoid too many queued jobs due to device maintenance/bad:

.. code-block:: python

 QUEUE_TIMEOUT_HOURS: 168,

User can still override this default queue timeout if specify queue timeout
directly in job definition:

.. code-block:: python

 timeouts:
   queue:
     hours: 336

.. _admin_control:

Controlling the Django Admin Interface
**************************************

Some instances may need to allow selected users to be Django superusers
to provide access to the `Django Admin Interface
<https://docs.djangoproject.com/en/3.2/ref/contrib/admin/>`_. Some of
the features of the interface need **very** careful handling,
especially the **deletion** of database objects.

Deleting database objects is **always** a problem and needs careful
consideration after looking at all the relevant logs. There are complex
inter-relationships not just in the UI but also in the scheduler,
logging support and publishing support. UI errors and scheduling errors
can be caused by inappropriate deletion of database objects and
recovery from these situations can be complex and may involve a
complete restoration of the instance from :ref:`backups
<admin_backups>`.

Admins can choose to disable access to the ``Delete`` button in
critical areas of the admin interface by adding a setting to
``/etc/lava-server/settings.conf``:

.. code-block:: json

 {
  "ALLOW_ADMIN_DELETE": false,
 }

This disables the ``Delete`` button and the ``delete`` action for
selected database objects, particularly Device, TestJob, TestCase,
TestSuite and TestSet. None of these objects should be deleted in
the admin interface (helpers exist to delete using the command line
interface, with suitable safeguards).

Restart the ``lava-server-gunicorn`` service each time
``/etc/lava-server/settings.conf`` is modified.

.. _log_size_limit:

Configuring log file display
****************************

By default, test logs will be formatted and displayed for easy viewing
in the browser and this should work fine for the majority of
users. However, if your test jobs are creating very large test logs it
can cause problems when trying to display them. Depending on network
and client configuration, this might show up as timeouts when viewing
or maybe error codes like "502 Proxy Error". If this is a problem,
there is an option to control the maximum size of test log that will
be displayed; any log larger than this will instead just be offered
for direct download.

Edit ``/etc/lava-server/settings.conf`` (JSON syntax) to set the
limit, in MiB. For example::

  "LOG_SIZE_LIMIT": "10",

will limit the maximum display size to 10 MiB. To find the right size
for your needs, check on the sizes of the ``output.yaml`` log files on
your lava-master server.

Some test jobs are generating a lot of test cases. For such test jobs,
rendering the log page could be really slow while the server query the database
for every test case ids.
In order to improve the page rendering speed, if more than
``TESTCASE_COUNT_LIMIT`` (10000 by default) test cases exists for a job, the
server will not query the test case table. The logs will still be visible, but
without the links to the result pages.

You can change the default value by editing
``/etc/lava-server/settings.conf``::

  "TESTCASE_COUNT_LIMIT": 1000,


Extending the schema white list
*******************************

Since LAVA 2019.04, the keys that can be used in the job definition **context**
dictionary is restricted. Admins can extend this white list by updating
``EXTRA_CONTEXT_VARIABLES`` in the settings:

Add to ``/etc/lava-server/settings.conf``::

  "EXTRA_CONTEXT_VARIABLES": ["custom_variable1", "variable_2"],
