Administrator debugging

Debugging a LAVA instance

Components

Each of these components has a service which may need to be restarted when making changes. Each of these services are restarted when the relevant packages are installed.

  • lava-server - the frontend UI and admin interface. If using apache use apache2ctl restart when changing any of the django files, device type templates or lava-server settings:

    $ sudo apache2ctl restart
    
  • master - the dispatcher master, controlling the slaves using ZMQ and scheduling jobs. The master does the pipeline validation. Restart when changing the dispatcher code (as the master runs the validation check using the dispatcher code):

    $ sudo service lava-master restart
    
  • slave - each dispatcher slave connects to the master using ZMQ and follows the instructions of the master, using configuration specified by the master. Restart is rarely needed, usually only when changing the dispatcher code related to ZMQ or the loghandler:

    $ sudo service lava-slave restart
    

The master and slave have dedicated singleton processes which should be put into loglevel DEBUG when investigating problems. Restart the service after editing the service file.

  • master /etc/init.d/lava-master currently defaults to DEBUG log level.
  • slave /etc/init.d/lava-slave currently defaults to DEBUG.

Log files

All log files use logrotate, so the information you need may be in a log.1 or log.2.gz file - typically up to log.9.gz. Use zless or zgrep for older log files.

  • apache - /var/log/apache2/lava-server.log
  • django - by default /var/log/lava-server/django.log contains errors and warnings from django.
  • master - /var/log/lava-server/lava-master.log
  • slave - /var/log/lava-dispatcher/lava-slave.log.
  • test jobs - /var/lib/lava-server/default/media/job-output/ individual files are in a directory named after the start time of the corresponding job <year>/<month>/<day/$ID, e.g. 2018/08/10/1234. The directory includes the validation output description.yaml and the full log file output.yaml.

Command line debugging

  • lava-server - sudo lava-server manage shell.

  • lava-dispatcher - The actions of lava-slave can be replicated on the command line. The relevant device configuration can be obtained using lavacli, e.g.:

    $ lavacli devices dict get --render DEVICE_HOSTNAME
    

    This config can then be passed to lava-run, in this example in a file named device.yaml:

    $ sudo lava-run --device device.yaml --output-dir /tmp/debug/ job.yaml
    

    Every job is validated before starting and the validate check can be run directly by adding the --validate option:

    $ sudo lava-dispatch --device device.yaml --validate --output-dir /tmp/debug/ job.yaml
    

    The job will not start when --validate is used - if validation passes, the complete pipeline will be described. If errors are found, these will be output.

Configuration files

  • lava-server - /etc/lava-server/settings.conf - restart apache and lava-server if this is changed. Holds details for django settings including the authentication methods and site customisation settings.

  • jinja2 templates - /etc/lava-server/dispatcher-config/device-types These files are updated from lava_scheduler_app/tests/device-types in the codebase. The syntax is YAML with jinja2 markup. Restart the lava-master after changing the templates.

    • to validate changes to the templates, use:

      $ /usr/share/lava-server/validate_devices.py --instance localhost
      
    • to validate the combination of the template with the device dictionary content, use:

      $ lavacli devices dict get --render DEVICE_HOSTNAME
      
  • device dictionaries - /etc/lava-server/dispatcher-config/devices These files are specific to each instance and need to be named according to the hostname.jinja2 of the device as configured on the same instance.

Check LAVA instance

Once a LAVA instance is installed admins can check for errors and warnings on the deployed instance using:

$ sudo lava-server manage check --deploy

The check --deploy command uses the Django system check framework which is a set of static checks to detect common problems and provide hints for how to fix them.

See also

https://docs.djangoproject.com/en/dev/ref/checks/ to know more about Django system check framework.

If the JSON syntax of /etc/lava-server/settings.conf is invalid, this check will display a warning: settings.conf is not a valid json file.

LAVA sets the following values by default:

SECURE_CONTENT_TYPE_NOSNIFF = True
SECURE_BROWSER_XSS_FILTER = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True
CSRF_COOKIE_HTTPONLY = True
X_FRAME_OPTIONS = 'DENY'

These values can be overridden in /etc/lava-server/settings.conf

The following checks are silenced and does not show any errors or warnings:

Note

Admins should consult the respective Django documentation before changing these values to suit the requirements of each LAVA instance.

Displaying current settings

The django developer shell can be used to check the value which is currently set:

$ sudo lava-server manage shell
Python 3.6.7 (default, Oct 21 2018, 08:08:16)
[GCC 8.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from django.conf import settings
>>> settings.CSRF_COOKIE_HTTPONLY
False

Caution

Avoid making changes to the defaults inside the LAVA code. These will be replaced when you upgrade to future versions of the lava-server package. If you need to make changes, instead edit /etc/lava-server/settings.conf where they will be preserved. Whenever you make changes, be sure to restart the LAVA daemons before checking for the effects of the change:

$ sudo service lava-server-gunicorn restart

In some situations, you may also need to restart lava-logs, lava-master and lava-publisher in the same way.

See also

Installing a new release or a set of Developer packages will also restart all LAVA daemons.

Django support in 1.11

If your local instance is using python3-django from stretch-backports or buster, the new support in 1.11 and later can be used to display the settings as well:

$ sudo lava-server manage diffsettings --all

Settings that don’t appear in the defaults are followed by “###”, e.g.:

BRANDING_MESSAGE = 'Master branch instance on Debian Stretch.'  ###

Danger

Access to lava-server manage needs to be restricted in the same way as read permissions on /etc/lava-server/settings.conf as the current settings will include the database secret_key, authentication passwords for services like LDAP and other sensitive information.