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
"""
from abc import abstractmethod
from typing import List, Optional

from aiohttp import ClientSession

from crutches_on_wheels.monitoring.points import BaseRequestMonitoringPoint
from crutches_on_wheels.plugins.plugins_meta.base_plugins import BaseEventPlugin
from crutches_on_wheels.web.application import LunaApplication
from crutches_on_wheels.utils.log import Logger


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

    # event name for triggering callback
    eventName = "monitoring_event"

    @abstractmethod
    async def flushPointToMonitoring(self, points: List[BaseRequestMonitoringPoint], logger: Logger) -> None:
        """
        All plugins must realize this method.

        This function call after end of request

        Args:
            points: points for monitoring which corresponding the request
            logger: logger
        """

    async def handleEvent(  # pylint: disable-msg=C0204,W0221
        self, points: List[BaseRequestMonitoringPoint], logger: Logger
    ):
        await self.flushPointToMonitoring(points=points, logger=logger)


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: Optional[ClientSession] = 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, points: List[BaseRequestMonitoringPoint], logger: Logger) -> None:
        """
        Callback for sending a request monitoring data.

        Args:
            points: point for monitoring which corresponding the request
            logger: logger
        """
        if not points:
            return
        point = points[0]
        logger.debug(
            f"Plugin 'flushPointToMonitoring' get point, request_id: {point.requestId}, "
            f"start 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 typing import Optional

from sanic.response import HTTPResponse

from crutches_on_wheels.plugins.plugins_meta.base_plugins import BaseBackgroundPlugin
from crutches_on_wheels.web.application import LunaApplication
from crutches_on_wheels.web.handlers import BaseHandler


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

    async def get(self) -> HTTPResponse:
        """
        Method get example.

        Returns:
            response
        """
        return self.success(body="I am teapot", contentType="text/plain", statusCode=418)

    @property
    def app(self):
        """
        Get app
        Abstract method of `BaseHandler`
        Returns:
            app
        """
        return self.request.app

    @property
    def config(self):
        """
        Get app config
        Abstract method of `BaseHandler`
        Returns:
            app config
        """
        return self.request.app.ctx.serviceConfig


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

    Create background task and add a route.
    """

    def __init__(self, app: LunaApplication):
        super().__init__(app)
        app.addRoutes([("/teapot", HandlerExample)])
        self.task: Optional[Task] = None
        self.temperature = 0

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

    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.

Matching plugins¶

Matching plugins intends to speed up matching requests.

Warning

Matching plugins refers only to Luna Python Matcher proxy service.

General information

Matching cost

Matching targets

Built-in matching plugins

Thin event plugin

Cached Matcher plugin

User matching plugins

Plugin data source

Plugin code

Enable plugin¶

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

Using plugins with containers¶

If using containerized application, there are several ways to include the plugins in the container:

Build your own image based on original one. See example Dockerfile below.

Mount plugin files into the container by using –mount flag.

Copy plugin files into the running container, commit changes to the new image (docker commit) and use newly created image.

FROM my-registry/luna-python-matcher:v.0.5.15

COPY --chown=1001:0 my_plugin ./luna_python_matcher/plugins/my_plugin