LAVA Hacking Sessions (JSON)

LAVA Hacking Sessions (JSON)


This chapter discusses a model which is being superceded by the pipeline model.

A LAVA hacking session is a lava-test-shell test that provides remote ssh access to a LAVA device.


  • The user has TCP/IP access to the device
  • The test job deployment raises a usable networking interface.


  • PUB_KEY - A plain-text string containing the ssh public key(s) you wish to use to connect to the device over ssh
  • IRC_USER - your IRC nick - the user will be alerted when the hacking session is ready for a connection with a private IRC message containing the details of how to connect to the session. (Debian hacking sessions only.)
  • testdef - The test definition (distrbution specific)
  • hacking-session-debian.yaml - run the hacking session on a Debian or Ubuntu filesystem, openssh-server will be installed using the package manager if not already installed. The test image must raise a network interface automatically (this can be done with lava_command_run, see example).
  • hacking-session-oe.yaml - run the hacking session on an Open Embedded filesystem. openssh-server must be installed in the test image
  • hacking-session-android.yaml - run the hacking session on an Android filesystem openssh-server must be installed in the test image. (The YAML for this session is still in review).


  • GATEWAY - The gateway for the network the target device is on - only needs to be set if the test is unable to determine the gateway correctly. (check with your LAVA admins)
  • IRC_SERVER - defaults to

Starting a Hacking Session

  • Create a LAVA job file with your desired target and image
  • Add a lava-test-shell action to your LAVA json job file where you want hacking access
    "command": "lava_test_shell",
    "parameters": {
        "testdef_repos": [
                "git-repo": "",
                "testdef": "hacking-session-debian.yaml",
                "parameters": {
                    "IRC_USER": "TYPE YOUR IRC NICK HERE",
                    "PUB_KEY": "PASTE_PUBKEY(S) HERE"
        "timeout": 3600

See Hacking Session timeouts for clarification of the timeout support.

Connecting to a Hacking Session

The hacking session test definition will report the commands to ssh within the LAVA log file. To access the log file, you can use a web browser; navigate to your hacking session and scroll to the end of the job to see instructions

  • This hack session was executed on Linaro’s LAVA system, job ID: 116632

SSH tunneling

If your target device is located on a remote server, as is the case when accessing the Linaro LAVA lab, you’ll want to tunnel onto the Linaro network to the device under test

  1. verify your SSH key is setup and configured to connect:

    ~# ssh -T
  2. Modify your SSH config to allow agent forwarding:

       ForwardAgent yes

lava-test-shell helper functions in a hack session

lava-test-shell helper functions can be found within target in the directory /lava/bin

Record text to the LAVA log

During a hacking session using a KVM, LAVA is listening to /dev/ttyS0 for the duration of the hacking session. From within the target any text you echo to /dev/ttyS0 will be recorded within LAVA.


/dev/ttyS0 is just an example which is likely to work for a KVM. /dev/console is not necessarily correct for most devices. The actual device may need to be looked up in /proc/cmdline or similar, prior to issuing the echo.

Stopping a Hacking Session

During a hacking session, the target your are connected to can’t be used for other tasks, so this holds up other users who may want to run tests using the device. Your session is monitored for Hacking Session timeouts, or you can complete your session immediately:

  • logout of your session (you can avoid closing the session on logout using the Continuing a Hacking Session support).
  • Cancel the job in the LAVA using the link in the job detail or job log pages.
  • Stop - Use the helper function stop_hacking from the command-line within the hacking session


Cancel will end the job immediately, there will not be any time to process the result bundle. Use stop_hacking to close the session and complete normal job processing.

Hacking Session timeouts


This behaviour changed after a session at Connect HKG15

All hacking sessions will timeout after 1 hour if a login has not been detected. If an IRC_USER is specified with a Debian hacking session, that user will get another IRC private message explaining the termination.

The timer is running for the lifetime of the hacking session, so if you use Continuing a Hacking Session and logout, you will still need to log back in within one hour.

The session will timeout, regardless of activity, when the timeout specified in the job is reached.

Continuing a Hacking Session

If you want to be able to logout of a hacking session and log back in within the inactivity timeout, call the continue_hacking script from the command line within the hacking session. The hacking session is still monitored for Hacking Session timeouts, so do remember to log back in.