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Lavabo

Lavabo is a tool to remotely control boards which are in a LAVA infrastructure.

Lavabo allows to remove a given board from the control of LAVA. Then it magically provides access to the board's serial and is able to power cycle the board as well as to send files to a TFTP server accessible from the board.

Overview

Lavabo is a two parts software, organized in a client-server fashion. A server part is running alongside the LAVA instance. The client is provided to control the boards from remote systems (from LAVA point of view). Last but not least, Lavabo tries as much as possible to reuse known software.

The server abstracts communication to the LAVA instance, and to other daemons controlling the boards. It uses directly LAVA to take control of the boards and parses its configuration to learn which commands to use to power-off, reset or get the board's serial. For now, Lavabo server only provides access to the devices controlled by the LAVA master node.

The client connects to the server through SSH and send commands. To get a serial, a port-forwarding SSH process is spawn and a local telnet instance is created. To send files, the SFTP protocol is used.

A third part of lavabo called lavabo-watchdog is also available to automatically send mail to people who reserved a board a long time ago and did not release it.

Requirements

Lavabo server needs a running LAVA instance, configured to access the board's serials with ser2net. The machine hosting Lavabo server should be accessible via SSH as all communications use this protocol.

Lavabo server will only work with pipeline (LAVA v2) devices.

Lavabo client needs a few programs to be installed: telnet, ssh, python-paramiko, python-argcomplete for autocompletion, python-tabulate for pretty printing the result of lavabo list.

Configuration

lavabo-server

A dedicated user (which has an authentication token) should be created in the LAVA instance. It will be used by the Lavabo server to interact with LAVA.

All communications will go through SSH. Lavabo uses an unique and dedicated UNIX user on the machine hosting Lavabo server. The multiplexing of users is done thanks to SSH commands. To achieve this, the UNIX user's $HOME/.ssh/authorized_keys` should contain one line per user who wants to use Lavabo. Example:

command="python /path/to/lavabo-server <user0's name> $SSH_ORIGINAL_COMMAND" <user0's public key>
command="python /path/to/lavabo-server <user1's name> $SSH_ORIGINAL_COMMAND" <user1's public key>
command="python /path/to/lavabo-server <user2's name> $SSH_ORIGINAL_COMMAND" <user2's public key>

User's name are used in lavabo to authenticate the users, given their SSH key. They are then used to make sure not more than one user is accessing a board at a time.

Also, give sufficient permission to the dedicated UNIX user to create directories in the TFTP directory used by LAVA (as advised when installing LAVA, it should be /var/lib/lava/dispatcher/tmp or look at /etc/default/tftpd-hpa):

# chgrp <user> /var/lib/lava/dispatcher/tmp
# chmod g+rwx /var/lib/lava/dispatcher/tmp

Complete the lavabo-server.conf with the LAVA user and token previously created. The URL of the LAVA server API (it should end with /RPC2) should also be specified.

lavabo

Copy lavabo.conf.sample as $HOME/.lavabo.conf and adapt it with the appropriate settings.

lavabo-watchdog

Adapt lavabo-watchdog.conf.sample to match your SMTP credentials and lab user authentication.

delta is the authorized delta in days between the reservation date and the current day before lavabo-watchdog shall send a reminder by mail.

working-dir is the directory from which lavabo-server is usually launched. It is the $HOME directory of the UNIX user used for lavabo-server on the machine hosting LAVA server. Basically, if you're connecting to lavabo-server with lab@lavabo-server.com, your working-dir would be /home/lab.

Add lavabo-watchdog to your cron table.

F.A.Q

Why?

We have a LAVA lab with boards we often own in only one copy. We have these boards included in KernelCI project which sends tests for different kernels to our LAVA lab in order to know if everything is working on the boards in our lab.

However, we sometime need to have direct access to the boards when work on the kernel is in progress. We do not want to put the boards physically outside of the lab each time we want to work on it. This means we want to be able to remotely power it on or off, get its serial connection and send files to it.

As we want to work on the board without being interrupted by LAVA, we also have to virtually put the board outside of our lab.

What can lavabo do on a board?

$ lavabo -h should be enough and is up-to-date.

What's the typical workflow?

$ lavabo list	# get a list of available boards
$ export LAVABO_BOARD=<board>
$ lavabo reserve

In a dedicated terminal:

$ lavabo serial

Then you can power-cycle the board and/or upload your kernel images:

$ lavabo upload zImage dtb
$ lavabo reset

Finally, it is IMPORTANT to put back the board under LAVA's control; otherwise the board won't be used in the farm and by Kernel CI jobs.

$ lavabo release

How are files served to the board?

LAVA uses TFTP to serve files to the board, so all we need is to send files from our laptop to the TFTP directory of the LAVA instance which can be specified by --tftp-dir in lavabo-server. We use SFTP protocol to perform this task. Thus, we can access from the board the files we need on LAVA instance TFTP server under a subdirectory named after the username specified with each SSH key.

How to enable autocompletion?

  • Bash:

Add eval "$(register-python-argcomplete lavabo)" to your .bashrc.

  • Zsh:

Add to your .zshrc: autoload -U +X compinit && compinit autoload -U +X bashcompinit && bashcompinit eval "$(register-python-argcomplete lavabo)"

Source: http://argcomplete.readthedocs.io/en/latest/#synopsis