## page was renamed from Celery
= Celery =
Celery is an asynchronous task queue/job queue based on distributed message passing.	

http://docs.celeryproject.org/en/latest/getting-started/first-steps-with-celery.html

== Slackware 14 installation ==
 * easy_install celery
 * pip install celery

Check installation: 
{{{#!highlight bash
python
Python 2.7.3 (default, Jul  3 2012, 19:58:39) 
[GCC 4.7.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import celery
>>> celery.__version__
'3.1.7'
>>>
}}}

== Test app with Redis ==
Run redis:
{{{#!highlight bash
$redis-server & 
$redis-cli     
redis 127.0.0.1:6379> quit
}}}

App:
{{{#!highlight python
# celeryTest.py
from celery import Celery

app = Celery('tasks', broker='redis://localhost')
app.conf.update(CELERY_RESULT_BACKEND="redis://")

@app.task
def add(x, y):
    return x + y
}}}

{{{#!highlight bash
$celery -A celeryTest worker --loglevel=info
}}}

Run task
{{{#!highlight bash
$ python
Python 2.7.3 (default, Jul  3 2012, 19:58:39) 
[GCC 4.7.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from celeryTest import add
>>> xx=add.delay(3,3)
>>> xx.ready()
True
>>> print(xx.result)
6
}}}

== Docker compose example ==
 * docker-compose stop
 * docker-compose build
 * docker-compose up

=== app.py ===
{{{#!highlight python
import time
import redis
from flask import Flask,jsonify
from celery import Celery

celery = Celery()
celery.config_from_object('celeryconfig')

"""
docker-compose build
docker-compose run
docker exec -it celerytest_web_1 sh
docker-compose buid
docker-compose restart

docker-compose stop
docker system prune -a
docker-compose up
docker exec -it celerytest_web_1 sh
pip freeze

"""

app = Flask(__name__)
cache = redis.Redis(host='redis', port=6379)

def get_hit_count():
    retries = 5
    while True:
        try:
            return cache.incr('hits')
        except redis.exceptions.ConnectionError as exc:
            if retries == 0:
                raise exc
            retries -= 1
            time.sleep(0.5)

@app.route('/')
def hello():
    count = get_hit_count()
    return 'Hello World!?= I have been seen {} times.\n'.format(count)

@app.route('/add/<int:op1>/<int:op2>')
def add(op1=None,op2=None):
    """
    http://localhost:5000/add/2/8
    """
    result=(celery.send_task('celery_worker.add', (op1,op2)))
    return jsonify( add_res=result.get())

@app.route('/mul/<int:op1>/<int:op2>')
def mul(op1=None,op2=None):
    """
    http://localhost:5000/mul/2/8
    """
    result=(celery.send_task('celery_worker.mul', (op1,op2)))
    return jsonify( add_res=result.get())
}}}

=== Dockerfile-celery ===
{{{
FROM python:3.7-alpine
WORKDIR /code
RUN apk add --no-cache gcc musl-dev linux-headers
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
EXPOSE 5000
COPY . .
CMD ["celery","-A","celery_worker","worker","--loglevel=info"]
}}}

=== Dockerfile ===
{{{
FROM python:3.7-alpine
WORKDIR /code
ENV FLASK_APP=app.py
ENV FLASK_RUN_HOST=0.0.0.0
RUN apk add --no-cache gcc musl-dev linux-headers
COPY requirements.txt requirements.txt
RUN pip install -r requirements.txt
EXPOSE 5000
COPY . .
CMD ["flask", "run"]
}}}

=== docker-compose.yml ===
{{{#!highlight yaml
version: "3.3"
services:
  web:
    build: .
    ports:
      - "5000:5000"
    volumes:
      - .:/code
    environment:
      FLASK_ENV: development
  redis:
    image: "redis:alpine"
  celery:
    build:
      context: .
      dockerfile: Dockerfile-celery
}}}

=== celery_client.py ===
{{{#!highlight python
from celery import Celery

def callback(taskid):
    print("callback taskid %s"%(taskid))
    print("callback ready %d task id %s"%(result.get() , result.task_id  ))

celery = Celery()
celery.config_from_object('celeryconfig')
result=(celery.send_task('celery_worker.add', (2,2)))

result.on_ready.then(callback) 
print(result.get())
}}}

=== celery_worker.py ===
{{{#!highlight python
from celery import Celery
from celery import shared_task

app = Celery('tasks', broker='redis://redis')
app.conf.update(CELERY_RESULT_BACKEND="redis://redis")

@app.task
def add(x, y):
    return x + y

@shared_task
def mul(x,y):
    return x*y
}}}

=== requirements.txt ===
{{{
flask
redis
celery
}}}

=== celeryconfig.py ===
{{{#!highlight python
broker_url = 'redis://redis'
result_backend = 'redis://redis'

task_serializer = 'json'
result_serializer = 'json'
accept_content = ['json']
timezone = 'Europe/Lisbon'
enable_utc = True
}}}