Setting up a LAVA instance

The LAVA design designates the machine running Django and PostgreSQL as the lava-master and all other machines connected to that master which will actually be running the jobs are termed lava-slave machines.

Dependencies and recommends

Debian has the concept of Dependencies which must be installed and Recommends which are optional but expected to be useful by most users of the package in question. Opting out of installing Recommends is supported when installing packages, so if admins have concerns about extra packages being installed on the slaves (e.g. if using ARMv7 slaves or simply to reduce the complexity of the install) then Recommends can be omitted for the installation of these dependencies,

The 2016.6 release added a dependency on python-guestfs. The Recommends for GuestFS can be omitted from the installation, if admins desire, but this needs to be done ahead of the upgrade to 2016.6:

$ sudo apt --no-install-recommends install python-guestfs

Installing just lava-server

The lava-server package is the main LAVA scheduler and frontend.

To install just the lava-server from the current packages, use:

$ sudo apt install lava-server
$ sudo a2dissite 000-default
$ sudo a2enmod proxy
$ sudo a2enmod proxy_http
$ sudo a2ensite lava-server.conf
$ sudo service apache2 restart

This will install lava-dispatcher and lava-server.

Other packages to consider:

  • lavapdu-client to control a PDU to allow LAVA to automatically power cycle a device.
  • lavapdu-daemon - only one daemon is required to run multiple PDUs.
  • ntp - some actions within LAVA can be time-sensitive, so ensuring that devices within your lab keep time correctly can be important.

Note

There is no support in V2 for linaro-media-create to manipulate hardware packs from Linaro, so this package can be removed once there are no V1 devices on the worker.

Installing the full lava set

Production installs of LAVA will rarely use the full lava set as it includes tools more commonly used by developers and test labs. These tools mean that the lava package brings more dependencies than when installing lava-server to run a production LAVA instance.

The lava package installs support for:

  • lava-dev - scripts to build developer packages based on your current git tree of lava-server or lava-dispatcher, including any local changes.

    Note

    lava-dev includes a lot of packages which are not typically used on a production master or worker.

  • vmdebootstrap for building your own Debian based KVM images.

  • lavapdu-client to control a PDU to allow LAVA to automatically power cycle a device.

  • lavapdu-daemon is recommended or you can use a single daemon for multiple PDUs.

  • ntp - some actions within LAVA can be time-sensitive, so ensuring that devices within your lab keep time correctly can be important.

Note

There is no support in V2 for linaro-media-create to manipulate hardware packs from Linaro, so this package can be removed once there are no V1 devices on the worker.

All of these packages can be installed separately alongside the main lava-server package, the lava package merely collects them into one set.

$ sudo apt install postgresql
$ sudo apt -t stretch-backports install lava
$ sudo a2dissite 000-default
$ sudo a2enmod proxy
$ sudo a2enmod proxy_http
$ sudo a2ensite lava-server.conf
$ sudo service apache2 restart

Installing master without Recommends

The lava-common binary package is new in 2018.5 and allows admins to choose not to install lava-dispatcher on the master if there are to be no devices assigned to the machine running lava-master. This is common for installations where there are multiple workers and the master is regularly busy. lava-server now _Recommends_ lava-dispatcher which means that admins can choose not to install it alongside lava-server:

$ sudo apt --no-install-recommends install lava-server lava-server-doc

Depending on the local configuration, some of the other recommended packages may also be desirable:

  • lava-coordinator
  • ntp

lava-server-doc can be omitted but this would be unusual - instances would need to be configured to have some other Help option in the menu using the CUSTOM_DOCS dictionary setting in /etc/lava-server/settings.conf and the Help links from pages within the LAVA UI would cause a 404 error for users, unless the Apache configuration was adjusted.

Installing lava-dispatcher

If this machine is only meant to be a dispatcher for connected devices, then just install lava-dispatcher. The lava-server package is only needed on the master in each LAVA instance.

$ sudo apt install lava-dispatcher
  1. Change the dispatcher configuration in /etc/lava-dispatcher/lava-slave to allow the init script for lava-slave (/etc/init.d/lava-slave) to connect to the relevant lava-master instead of localhost. Change the port numbers, if required, to match those in use on the lava-master:

    /etc/lava-dispatcher/lava-slave
    
    # Configuration for lava-slave daemon
    
    # URL to the master and the logger
    # MASTER_URL="tcp://<lava-master-dns>:5556"
    # LOGGER_URL="tcp://<lava-master-dns>:5555"
    
    # Enable IPv6 to connect to the master and logger
    # IPV6="--ipv6"
    
    # Slave hostname
    # Should be set for host that have random hostname (containers, ...)
    # The hostname can be any unique string, except "lava-logs" which is reserved
    # for the lava-logs daemon.
    # HOSTNAME="--hostname <hostname.fqdn>"
    
    # Logging level should be uppercase (DEBUG, INFO, WARN, ERROR)
    # LOGLEVEL="DEBUG"
    
    # Encryption
    # If set, will activate encryption using the master public and the slave
    # private keys
    # ENCRYPT="--encrypt"
    # MASTER_CERT="--master-cert /etc/lava-dispatcher/certificates.d/<master.key>"
    # SLAVE_CERT="--slave-cert /etc/lava-dispatcher/certificates.d/<slave.key_secret>"
    
  2. Restart lava-slave once the changes are complete:

    $ sudo service lava-slave restart
    
  3. The administrator of the master will then be able to allocate pipeline devices to this slave.

Note

For security reasons, the slave does not declare the devices connected to it to the master. The LAVA configuration on the slave actually needs no knowledge of what is connected or where as long as services like ser2net are configured. All the LAVA configuration data is stored solely in the database of the master. Once this data is entered by the admin of the master, the slave then needs to connect and the admin can then select that slave for the relevant devices. Once selected, the slave can immediately start running pipeline jobs on those devices.

The administrator of the master will require the following information about the devices attached to each slave:

  1. Confirmation that a suitable template already exists, for each device i.e. Adding support for a device of a known type
  2. A completed and tested device dictionary for each device.

This information contains specific information about the local network setup of the slave and will be transmitted between the master and the slave in clear text over ZMQ. Any encryption would need to be arranged separately between the slave and the master. Information typically involves the hostname of the PDU, the port number of the device on that PDU and the port number of the serial connection for that device. The slave is responsible for ensuring that these ports are only visible to that slave. There is no need for any connections to be visible to the master.

Configuring apache2 on a worker

Some test job deployments will require a working Apache2 server to offer deployment files over the network to the device:

$ sudo cp /usr/share/lava-dispatcher/apache2/lava-dispatcher.conf /etc/apache2/sites-available/
$ sudo a2ensite lava-dispatcher
$ sudo service apache2 restart
$ wget http://localhost/tmp/
$ rm index.html

You may also need to disable any existing apache2 configuration if this is a default apache2 installation:

$ sudo a2dissite 000-default
$ sudo service apache2 restart

Adding workers to the master

A new worker needs to be manually added to the master so that the admins of the master have the ability to assign devices in the database and enable or disable the worker.

To add a new worker:

$ sudo lava-server manage workers add <HOSTNAME>

To add a worker with a description:

$ sudo lava-server manage workers add --description <DESC> <HOSTNAME>

To add a worker in a disabled state:

$ sudo lava-server manage workers add --description <DESC> --disabled <HOSTNAME>

Workers are enabled or disabled in the Django admin interface by changing the display field of the worker. Jobs submitted to devices on that worker will fail, so it is also recommended that the devices would be made offline at the same time. (The django admin interface has support for selecting devices by worker and taking all selected devices offline in a single action.)

Note

lava-logs is a reserved hostname. Any worker connecting with that hostname will be rejected by lava-master.

Using ZMQ authentication and encryption

lava-master and lava-slave use ZMQ to pass control messages and log messages. When using a slave on the same machine as the master, this traffic does not need to be authenticated or encrypted. When the slave is remote to the master, it is strongly recommended that the slave authenticates with the master using ZMQ curve so that all traffic can then be encrypted and the master can refuse connections which cannot be authenticated against the credentials configured by the admin.

To enable authentication and encryption, you will need to restart the master and each of the slaves. Once the master is reconfigured, it will not be possible for the slaves to communicate with the master until each is configured correctly. It is recommended that this is done when there are no test jobs running on any of the slaves, so a maintenance window may be needed before the work can start. ZMQ is able to cope with short interruptions to the connection between master and slave, so depending on the particular layout of your instance, the changes can be made on each machine before the master is restarted, then the slaves can be restarted. Make sure you test this process on a temporary or testing instance if you are planning on doing this for a live instance without using a maintenance window.

Encryption is particularly important when using remote slaves as the control socket (which manages starting and ending testjobs) needs to be protected when it is visible across open networks. Authentication ensures that only known slaves are able to connect to the master. Once authenticated, all communication will be encrypted using the certificates.

Protection of the secret keys for the master and each of the slaves is the responsibility of the admin. If a slave is compromised, the admin can delete the certificate from /etc/lava-dispatcher/certificates.d/ and restart the master daemon to immediately block that slave.

Create certificates

Encryption is supported by default in lava-master and lava-slave but needs to be enabled in the init scripts for each daemon. Start by generating a master certificate on the master:

$ sudo /usr/share/lava-dispatcher/create_certificate.py master

Now generate a unique slave certificate on each slave. The default name for any slave certificate is just slave but this is only relevant for testing. Use a name which relates to the hostname or location or other unique aspect of each slave. The admin will need to be able to relate each certificate to a specific slave machine:

$ sudo /usr/share/lava-dispatcher/create_certificate.py foo_slave_1

Distribute public certificates

Copy the public component of the master certificate to each slave. By default, the master public key will be /etc/lava-dispatcher/certificates.d/master.key and needs to be copied to the same directory on each slave.

Copy the public component of each slave certificate to the master. By default, the slave public key will be /etc/lava-dispatcher/certificates.d/slave.key.

Admins need to maintain the set of slave certificates in /etc/lava-dispatcher/certificates.d - only certificates declared by active slaves will be used but having obsolete or possibly compromised certificates available to the master is a security risk.

Preparation

Once enabled, the master will refuse connections from any slave which are either not encrypted or lack a certificate in /etc/lava-dispatcher/certificates.d/. So before restarting the master, stop each of the slaves:

$ sudo service lava-slave stop

Enable master encryption

The master will only authenticate the slave certificates if the master is configured with the --encrypt option. Edit /etc/lava-server/lava-master to enable encryption:

# Encryption
# If set, will activate encryption using the master public and the slave
# private keys
ENCRYPT="--encrypt"

Also edit /etc/lava-server/lava-logs to enable encryption:

# Encryption
# If set, will activate encryption using the master public and the slave
# private keys
ENCRYPT="--encrypt"

If you have changed the name or location of the master certificate or the location of the slave certificates, specify those locations and names explicitly, in each file:

# MASTER_CERT="--master-cert /etc/lava-dispatcher/certificates.d/<master.key_secret>"
# SLAVES_CERTS="--slaves-certs /etc/lava-dispatcher/certificates.d"

Note

Each master needs to find the secret key for that master and the directory containing all of the public slave keys copied onto that master by the admin.

See also

Preparation

Enable slave encryption

See also

Preparation

Edit /etc/lava-dispatcher/lava-slave to enable encryption by adding the enabling the --encrypt argument:

# Encryption
# If set, will activate encryption using the master public and the slave
# private keys
ENCRYPT="--encrypt"

If you have changed the name or location of the master certificate or the location of the slave certificates, specify those locations and names in /etc/lava-dispatcher/lava-slave explicitly:

# MASTER_CERT="--master-cert /etc/lava-dispatcher/certificates.d/<master.key>"
# SLAVE_CERT="--slave-cert /etc/lava-dispatcher/certificates.d/<slave.key_secret>"

Note

Each slave refers to the secret key for that slave and the public master key copied onto that slave by the admin.

Restarting master and slaves

For minimal disruption, the master and each slave can be prepared for encryption and authentication without restarting any of the daemons. Only upon restarting the master will the slaves need to authenticate.

Once all the slaves are configured restart the master and check the logs for a message showing that encryption has been enabled on the master. e.g.

2018-02-05 11:33:55,933    INFO [INIT] Marking all workers as offline
2018-02-05 11:33:55,983    INFO [INIT] Starting encryption
2018-02-05 11:33:55,984   DEBUG [INIT] Opening master certificate: /etc/lava-dispatcher/certificates.d/master.key_secret
2018-02-05 11:33:55,985   DEBUG [INIT] Using slaves certificates from: /etc/lava-dispatcher/certificates.d/
2018-02-05 11:33:55,986    INFO [INIT] LAVA master has started.
2018-02-05 11:33:55,986    INFO [INIT] Using protocol version 2

Now restart each slave in turn and watch for equivalent messages in the logs:

2018-02-05 11:34:42,035    INFO [INIT] LAVA slave has started.
2018-02-05 11:34:42,036    INFO [INIT] Using protocol version 2
2018-02-05 11:34:42,037    INFO [INIT] Starting encryption
2018-02-05 11:34:42,037   DEBUG Opening slave certificate: /etc/lava-dispatcher/certificates.d/codehelp.key_secret
2018-02-05 11:34:42,038   DEBUG Opening master certificate: /etc/lava-dispatcher/certificates.d/master.key
2018-02-05 11:34:42,038    INFO [INIT] Connecting to master as <codehelp>
2018-02-05 11:34:42,038    INFO [INIT] Greeting the master => 'HELLO'
2018-02-05 11:34:42,050    INFO [INIT] Connection with master established
2018-02-05 11:34:42,050    INFO Master is ONLINE
2018-02-05 11:34:42,053    INFO Waiting for instructions

Adding devices to a worker

Admins use the Django admin interface to add devices to workers using the worker drop-down in the device detail page.

Note

A worker may have a description but does not have a record of the IP address, uptime or architecture in the Worker object.