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.. index:: multiple devices
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Use Case Two - Setting up the same job on multiple devices
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**********************************************************
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One test definition (or one set of test definitions) to be run on
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multiple devices of the same device type.
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The test definition itself could be an unchanged singlenode test definition, e.g.
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https://git.linaro.org/qa/test-definitions.git/blob/HEAD:/ubuntu/smoke-tests-basic.yaml
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Alternatively, it could use the MultiNode API to synchronise the devices, e.g.
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https://git.linaro.org/people/neil.williams/multinode-yaml.git/blob_plain/HEAD:/multinode01.yaml
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https://git.linaro.org/people/neil.williams/multinode-yaml.git/blob_plain/HEAD:/multinode02.yaml
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https://git.linaro.org/people/neil.williams/multinode-yaml.git/blob_plain/HEAD:/multinode03.yaml
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* Multiple devices running the same test definition.
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* Running multiple test definitions at the same time on all devices in the group.
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* Synchronising multiple devices during a test.
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* Filter the results by device name.
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In the first part of this use case, the same YAML file is to be used to
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test multiple devices. Select your YAML file and, if appropriate, edit
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the name in the metadata.
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The change from a standard single-node JSON file is to expand the device_type
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or device field to a device_group.
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The change for multiple devices in MultiNode is within the ``device_group``. To run the test
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multiple devices of the same type, simply increase the ``count``:
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"device_type": "panda"
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If the rest of the JSON refers to a ``role`` other than the one specified
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in the ``device_group``, those JSON sections are ignored.
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If other actions in the JSON do not mention a ``role``, the action will
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occur on all devices in the ``device_group``. So with a single role,
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it only matters that a role exists in the ``device_group``.
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"command": "deploy_linaro_image",
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"image": "https://releases.linaro.org/13.03/ubuntu/panda/panda-quantal_developer_20130328-278.img.gz"
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To run multiple test definitions from one or multiple testdef repositories,
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expand the testdef_repos array:
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.. tip:: Remember the JSON syntax.
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- continuations need commas, completions do not.
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"command": "lava_test_shell",
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"git-repo": "git://git.linaro.org/people/neilwilliams/multinode-yaml.git",
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"testdef": "multinode01.yaml"
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"git-repo": "git://git.linaro.org/people/neilwilliams/multinode-yaml.git",
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"testdef": "multinode02.yaml"
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"git-repo": "git://git.linaro.org/people/neilwilliams/multinode-yaml.git",
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"testdef": "multinode03.yaml"
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The results for the entire group get aggregated into a single result
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"command": "submit_results_on_host",
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"stream": "/anonymous/instance-manager/",
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"server": "http://validation.linaro.org/RPC2/"
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Prepare a filter for the results
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================================
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The filter for this use case uses a ``required attribute``
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of **target.device_type** to only show results for the specified
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devices (to cover reuse of the YAML on other boards later).
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It is also possible to add a second filter which matches a specific **target**
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Adding synchronisation
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======================
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So far, the multiple devices have been started together but then had no
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The :ref:`multinode_api` supports communication between devices within
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a group and provides synchronisation primitives. The simplest of these
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primitives, :ref:`lava_sync` was used in :ref:`use_case_one` but there are more
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possibilities available.
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:ref:`lava_sync` is a special case of a :ref:`lava_send` followed by a
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:ref:`lava_wait_all`.
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Messages can be sent using :ref:`lava_send` which is a non-blocking call.
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At a later point, another device in the group can collect the message
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using ``lava-wait`` or ``lava-wait-all`` which will block until
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the message is available.
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The message can be a simple identifier (e.g. 'download' or 'ready') and
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is visible to all devices in the group.
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Key value pairs can also be sent using the API to broadcast particular
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If multiple devices send the same message ID, the data is collated by
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the LAVA Coordinator. Key value pairs sent with any message ID are
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tagged with the device name which sent the key value pairs.
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Message reception will block until the message is available.
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For :ref:`lava_wait`, the message is deemed available as soon as any device
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in the group has sent a message with the matching ID. If no devices have
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sent such a message, any device asking for ``lava-wait`` on that ID
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will block until a different board uses ``lava-send`` with the expected
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For :ref:`lava_wait_all`, the message is only deemed available if **all
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devices in the group** have already sent a message with the expected message
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ID. Therefore, using ``lava-wait-all`` requires a preceding
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When using ``lava-wait-all MESSAGEID ROLE``, the message is only deemed
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available if **all devices with the matching role in the group** have
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sent a message with the expected message ID. If the receiving device has
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the specified role, that device must use a ``lava-send`` for the same
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message ID before using ``lava-wait-all MESSAGEID ROLE``.
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- lava-test-case multinode-send-network --shell lava-send ready
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- lava-test-case multinode-get-network --shell lava-wait ready
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It is up to the test writer to ensure that when :ref:`lava_wait` is used,
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that the message ID is sufficiently unique that the first use of that
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message ID denotes the correct point in the YAML.
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- lava-test-case multinode-send-message --shell lava-send sending source=$(lava-self) role=$(lava-role) hostname=$(hostname -f) kernver=$(uname -r) kernhost=$(uname -n)
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- lava-test-case multinode-wait-message --shell lava-wait-all sending
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This example will wait until all devices in the group have sent the
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message ID ``sending`` (with or without the associated key value pairs).
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http://git.linaro.org/people/neil.williams/multinode-yaml.git/blob_plain/HEAD:/json/panda-only-group.json
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http://multinode.validation.linaro.org/dashboard/image-reports/panda-multinode
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doc/usecasetwo.rst
