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https://github.com/tcbegley/dash-rq-demo

Long running tasks in Dash using RQ
https://github.com/tcbegley/dash-rq-demo

heroku plotly-dash redis rq

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Long running tasks in Dash using RQ

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README 

        
# README



This repository demonstrates use of Redis and RQ for asynchronously executing

long running tasks in Plotly Dash. The task the app executes is meaningless, it

converts a string to upper case character by character with a time delay for

each character. Hopefully however the programming pattern is clear and the

example should be easily adaptable to other applications.



From the [RQ docs][rq-docs]:



> RQ (Redis Queue) is a simple Python library for queueing jobs and processing

> them in the background with workers.



This example uses a callback to add longer running tasks to an RQ job queue. A

second callback firing on an interval checks the current status of the job,

either retrieving the result or updating a progress bar to indicate progress

made on the task.



This example can be run locally, or deployed as is to [Heroku][heroku].



## Run locally



Start by cloning this repository to your machine.



```

git clone https://github.com/tcbegley/dash-rq-demo.git

cd dash-rq-demo

```



### Docker



If you have [Docker][docker] installed, run the app with



```sh

docker compose up

```



The app can be accessed at [localhost:8050](https://127.0.0.1:8050).



You can alternatively run `docker-compose.dev.yml` for development purposes.

This volume mounts the source code into the container and uses a development

server so that you can benefit from hot-reloading without rebuilding the

container.



```sh

docker compose -f docker-compose.dev.yml up

```

### Run manually



If you don't want to use Docker, first make sure you have

[Python>=3.7][python37] and [Redis][redis] installed. Once you've done this you

will need to [start a Redis server][redis-server]. See the links for more

details, but probably you will want to run something like:



```sh

redis-server &

```



Then do the following (preferably in a virtual environment):



```sh

pip install -r requirements.txt



# runs worker.py in the background and run_locally.py

python worker.py & python run_locally.py

```



The app can be accessed at [localhost:8050](https://127.0.0.1:8050).



## Heroku



To deploy your own copy of this app on Heroku, just click on this button:



[![Deploy](https://www.herokucdn.com/deploy/button.svg)][deploy-endpoint]



**Note**: you may need to wait a few minutes for the Redis addon to start before the app starts working.



Alternatively if you would like to set things up manually, follow the below

steps. You will need to install the [Heroku CLI][heroku-cli].



First clone this repository and navigate to it



```sh

git clone https://github.com/tcbegley/dash-rq-demo.git

cd dash-rq-demo

```



Create a new Heroku app and push the contents of this repository



```sh

heroku create

git push heroku main

```



Create the Redis addon, note that this can take a few minutes to start.



```sh

heroku addons:create heroku-redis:hobby-dev

```



You can check the status of the addon with the following command. The app will not work until the addon has been successfully created.



```sh

heroku addons:info heroku-redis

```



Add a worker to handle the background tasks.



```sh

heroku scale worker=1

```



Open the deployed app in your browser



```sh

heroku open

```



## Contributing



If something is unclear or you find a bug feel free to submit an issue or pull

request.



[deploy-endpoint]: https://heroku.com/deploy?template=https://github.com/tcbegley/dash-rq-demo

[docker]: https://www.docker.com/

[heroku]: https://www.heroku.com/

[heroku-cli]: https://devcenter.heroku.com/articles/heroku-cli

[python37]: https://www.python.org/

[redis]: https://redis.io/

[redis-server]: https://redis.io/topics/quickstart#starting-redis

[rq-docs]: https://python-rq.org/