guillotina-amqp 2.2.7

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.