Plugins¶

The service supports the system of plugins. Plugins must be written in the Python programming language.

Plugin types¶

There are three sorts of plugins:

On event plugin. The plugin is triggered when an event occurs. The plugin should implement a callback function. This function is called on each event of the corresponding type. The set of event types is defined by the service developers.

Supported event types:

event type

description

monitoring_event

Event contains monitoring points for sending to a custom monitoring system

event type	description
monitoring_event	Event contains monitoring points for sending to a custom monitoring system

Plugin example:

"""
Module request monitoring plugin example
"""
import asyncio
from abc import abstractmethod

from aiohttp import ClientSession
from luna_plugins.base.plugins_meta.base_plugins import BaseEventPlugin


class BaseRequestMonitoringPlugin(BaseEventPlugin):
    """
    Base class for requests monitoring.
    """

    # event name for triggering callback
    eventName = "monitoring_event"

    @abstractmethod
    async def flushPointToMonitoring(self, point: "MonitoringPoint", logger) -> None:
        """
        All plugins must realize this method.

        This function call after end of request

        Args:
            point: point for monitoring
            logger: logger
        """

    async def handleEvent(self, points: list["MonitoringPoint"], logger):
        await asyncio.gather(*[self.flushPointToMonitoring(point, logger) for point in points])


class RequestMonitoringPlugin(BaseRequestMonitoringPlugin):
    """
    Example plugin sends a request data for monitoring to third-party source.
    Only one instance of this class exist during the program execution.
    """

    def __init__(self, app: "LunaApplication"):
        super().__init__(app)
        self.url = "http://127.0.0.1:5020/1/buckets"
        self.session: ClientSession | None = None
        self.bucket = "plugin_test_bucket"

    async def close(self):
        """
        Stop plugin.

        Close all open connections and ect
        """
        if self.session:
            await self.session.close()

    async def initialize(self):
        """
        Initialize plugin.

        Close all open connections and ect
        """
        self.session = ClientSession()
        async with self.session.post(f"{self.url}?bucket={self.bucket}") as resp:
            if resp.status not in (201, 409):
                response = await resp.json()
                raise RuntimeError(f"failed create bucket, {self.bucket}, response: {response}")

    async def flushPointToMonitoring(self, point: "MonitoringPoint", logger) -> None:
        """
        Callback for sending a request monitoring data.

        Args:
            point: point for monitoring
            logger: logger
        """
        logger.debug(f"Plugin 'flushPointToMonitoring' get point, series: {point.series}, time: {point.eventTime}")
        msg = {"tags": point.tags, "fields": point.fields}
        async with self.session.post(f"{self.url}/{self.bucket}/objects", json=msg) as resp:
            logger.info(resp.status)
            logger.info(await resp.text())

This plugin demonstrates the sending of a request monitoring data to another service. All monitoring plugins must implement the BaseRequestMonitoringPlugin abstract class.

Background plugin. This sort of plugin is intended for background work.

The background plugin can implement:

custom route
background monitoring of service resources
collaboration of an event plugin and a background plugin (batching monitoring points)
connection to other data sources (Redis, RabbitMQ) and their data processing

Plugin example:

"""
Module realizes background plugin example
"""
import asyncio
from asyncio import Task

from luna_plugins.base.plugins_meta.base_plugins import BaseBackgroundHandler, BaseBackgroundPlugin, pluginHTTPResponse


class HandlerExample(BaseBackgroundHandler):
    """
    Handler example
    """

    async def get(self, request):  # pylint: disable=unused-argument
        """
        Method get example.

        Returns:
            response
        """
        return self.response(body="I am teapot", headers={"Content-Type": "text/plain"}, statusCode=418)


def anotherHandlerExample(request):  # pylint: disable=unused-argument
    """Standalone handler example"""
    return pluginHTTPResponse(statusCode=200, body="T800", headers={"Content-Type": "text/plain"})


class BackgroundPluginExample(BaseBackgroundPlugin):
    """
    Background plugin example.

    Create background task and add a route.
    """

    def __init__(self, app: "LunaApplication"):
        super().__init__(app)
        self.task: Task | None = None
        self.temperature = 0

    async def initialize(self):
        """
        Initialize plugin
        """
        self.addRoute("/teapot", HandlerExample)
        self.addRoute("/teapot/version", anotherHandlerExample, methods={"get"})

    async def close(self):
        """
        Stop background process
        Returns:

        """
        if self.task:
            self.task.cancel()

    async def usefulJob(self):
        """
        Some useful  async work
        """
        while True:
            await asyncio.sleep(1)
            self.temperature = min(100, self.temperature + 1)
            if self.temperature < 100:
                self.app.ctx.logger.info(f"I boil water, temperature: {self.temperature}")
            else:
                self.app.ctx.logger.info("boiling water is ready, would you care for a cup of tea?")

    async def start(self):
        """
        Run background process

        .. warning::
            The function suppose that the process is handle in this coroutine. The coroutine must start
            the process only without awaiting a end of the process
        """
        self.task = asyncio.create_task(self.usefulJob())

This plugin demonstrates background work and implements a route. All background plugins must implement the BaseRequestMonitoringPlugin abstract class.

Builtin plugin. This sort of plugin is provided only by VL and allow to get access to external VL services which not included to luna-platform. Each plugin provides access to part or whole resources of external service.

At this moment available plugins are:

luna-streams

The plugin also check authorization parameters for access to several resources. It is possible to use Luna-Account-Id/Basic/Bearer authorization to make requests just like for all other endpoint of luna-api.

It is also possible to delimit access permissions using token permission. To make it possible, it needs to create new or update existing token passing custom token permission keys, for example {“permissions”: {“streams”: [“creation”, “view”, “modification”, “deletion”]}}

These parameters will works the same way as for all other luna-api resources.

Luna-Streams builtin plugin

Requirements:

properly executed Luna-Streams service

properly specified plugin settings. For example:

"LUNA_API_PLUGINS_SETTINGS": {
        "luna-streams": {
            "luna-streams-address": {"origin": "http://127.0.0.1:5160/1", "api_version": 1},
            "luna-streams-timeouts": {"request": 42, "connect": 42}
        }
    }
}

* prefix is /6/plugins/luna-streams

luna-api route	luna-streams route	description	permission key
prefix/version	/version	get luna-streams api version
prefix/docs/spec	/1/docs/spec	get luna-streams spec documentation
prefix/streams	/1/streams	create new/get/delete existing streams	streams
prefix/streams/count	/1/streams/count	get streams count	streams
prefix/streams/<stream-id>	/1/streams/<stream-id>	replace/get/delete stream	streams
prefix/plugins	/1/plugins	get list of active plugins
prefix/streams/logs	/1/streams/logs	get/delete streams logs	streams
prefix/streams/<stream-id> /preview/handler/live	/1/streams/<stream-id> /preview/handler/live	get stream live preview	streams streams
prefix/streams/<stream-id> /preview/handler/frame	/1/streams/logs /preview/handler/frame	get stream frame preview	streams streams

Enable plugin¶

If the user implements a plugin, the file with the plugin should be added to the luna_api/plugins directory of the service. The plugin filename should be added to the LUNA_API_ACTIVE_PLUGINS configuration setting.