guillotina-amqp 3.0.1

Integrate amqp into guillotina

guillotina_amqp Docs

Integrates aioamqp into guillotina, providing an execution framework for asyncio tasks:

• Guillotina command to start a worker: amqp-worker

• Workers consume tasks from rabbit-mq through the aioamqp integration

• Redis state manager implementation to keep a global view of running tasks

• Utilities and endpoints for adding new tasks and for task cancellation

Its distributed design - the absence of a central worker manager - makes it more robust. Task cancelation is signaled over the state manager, and workers will be responsible for stopping canceled tasks.

A watchdog on the asyncio loop can be launched with the auto-kill-timeout command argument, which will kill the worker if one of its tasks has captured the loop for too long.

When a task fails, the worker will send it to the delay queue, which has been configured to re-queue tasks to the main queue after a certain TTL. Failed tasks are retried a limited amount of times.

Configuration

Example docs:

{
    "amqp": {
        "host": "localhost",
        "port": 5673,
        "login": "guest",
        "password": "guest",
        "vhost": "/",
        "heartbeat": 800,
        "queue": "guillotina",  # Main consuming queue for workers
        "persistent_manager": "redis",
        "delayed_ttl_ms": 60 * 1000,
        "errored_ttl_ms": 1000 * 60 * 60 * 24 * 7,
    }
}

• host and port: should point to the rabbit-mq instance

• login and password: should match the rabbit-mq access credentials

• queue: main queue where tasks are consumed from

• persistent_manager: named utility to use to keep tasks state.

• delay_ttl_ms and errored_ttl_ms: can be used to configure queue delays. Default to 2 minutes and 1 week, correspondingly.

• max_running_tasks: maximum number of simultaneous asyncio tasks hat workers are allowed to run.

Dependencies

Python >= 3.6

Installation

This example will use virtualenv:

virtualenv .
./bin/pip install .[test]

Running

Most simple way to get running:

./bin/guillotina

Queue tasks

code:

from guillotina_amqp import add_task
await add_task(my_func, 'foobar', kw_arg='blah')

With decorators

code:

from guillotina_amqp import task

@task
async def my_func(foo):
    print(foo)

await my_func('bar')

Run the worker

command:

g amqp-worker

You can use a couple of additional parameters:

• –auto-kill-timeout: time of inactivity after which the worker will restart himself assuming it got stuck.

• –max-running-tasks: max number of simultaneous asyncio tasks in the event loop. Overwrites configuraiton parameter.

Beacons

The aioamqp client can get stuck on a closed connection and the worker would be running forever without processing any message.

As a workaround, we implemented a beacon system independent for every worker. When getting a new connection to rabbitmq, we create a beacon queue and a beacon-delay queue. Both are exclusive queues, which means that will be removed after the connection from the worker is closed.

On the background of every connection, we publish a beacon message to the beacon-delay queue, which is expected to be read again after a certain TTL from the beacon queue. If a beacon message is not received after 3 times the TTL, the worker will exit.

API

• GET /@amqp-tasks - get list of tasks

• GET /@amqp-tasks/{task_id} - get task info

• DELETE /@amqp-tasks/{task_id} - delete task