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| title | layout |
|---|---|
| RQ: Using RQ on Heroku | patterns |
Using RQ on Heroku
To setup RQ on Heroku, first add it to your
requirements.txt file:
redis>=3
rq>=0.13
Create a file called run-worker.py with the following content (assuming you
are using Redis To Go with Heroku):
{% highlight python %} import os import urlparse from redis import Redis from rq import Queue, Connection from rq.worker import HerokuWorker as Worker
listen = ['high', 'default', 'low']
redis_url = os.getenv('REDISTOGO_URL') if not redis_url: raise RuntimeError('Set up Redis To Go first.')
urlparse.uses_netloc.append('redis') url = urlparse.urlparse(redis_url) conn = Redis(host=url.hostname, port=url.port, db=0, password=url.password)
if name == 'main': with Connection(conn): worker = Worker(map(Queue, listen)) worker.work() {% endhighlight %}
Then, add the command to your Procfile:
worker: python -u run-worker.py
Now, all you have to do is spin up a worker:
{% highlight console %} $ heroku scale worker=1 {% endhighlight %}
If you are using Heroku Redis) you might need to change the Redis connection as follows:
{% highlight console %} conn = redis.Redis( host=host, password=password, port=port, ssl=True, ssl_cert_reqs=None ) {% endhighlight %}
and for using the cli:
{% highlight console %} rq info --config rq_conf {% endhighlight %}{% endhighlight %}
Where the rq_conf.py file looks like: {% highlight console %} REDIS_HOST = "host" REDIS_PORT = port REDIS_PASSWORD = "password" REDIS_SSL = True REDIS_SSL_CA_CERTS = None REDIS_DB = 0 REDIS_SSL_CERT_REQS = None {% endhighlight %}{% endhighlight %}
Putting RQ under foreman
Foreman is probably the process manager you use when you host your app on Heroku, or just because it's a pretty friendly tool to use in development.
When using RQ under foreman, you may experience that the workers are a bit quiet sometimes. This is because of Python buffering the output, so foreman
cannot (yet) echo it. Here's a related Wiki page.
Just change the way you run your worker process, by adding the -u option (to
force stdin, stdout and stderr to be totally unbuffered):
worker: python -u run-worker.py