rest_queue

rest_queue is a simple demonstration of creating a REST service to host one or more FIFO queues, shareable across multiple producers and consumers.

Background

rest_queue originated out of some discussion on the StackOverflow Python chat, regarding sharing of a queue across multiple Python processes. The initial question was how to connect to a queue that had already been created in a running Python program. Several alternatives were posed, but most were very low-level, or did not support access by new external Python processes.

My suggestion was to create a small REST service that would manage a single queue, which any Python script could then connect to and push or pop items from the queue. All that would be needed would be the base URL of the REST service. So after the discussion died down, I made an attempt at creating my own such REST service.

I chose FastAPI as the framework with which to create the REST service, as I wanted to make a small project with it to learn more about it. The actual implementation was very straightforward, once I settled on the API endpoints.

I also extended the original concept, where the server managed just a single queue, to support multiple queues, to be a better illustration of REST interactions with a server managing multiple resources.

REST API

Function	REST method	URL	Return status
Create Queue	POST	/queues/{queue_name}	201 - Queue created 409 - Queue exists
Queue Push	POST	/queues/{queue_name}/push	200 - Operation successful 404 - No such queue
Queue Pop	POST	/queues/{queue_name}/pop	200 - Operation successful 404 - No such queue
List Queue Items	GET	/queues/{queue_name}	200 - Operation successful 404 - No such queue
Delete Queue	DELETE	/queues/{queue_name}[?safe_delete=true]	200 - Operation successful 404 - No such queue 409 - Queue is not empty (safe_mode=True)
List All Queues	GET	/queues	200 - Operation successful

Deploying

Manual

The rest_queue server can be run locally by entering commands at the terminal console. Install Python 3.6 or later, and after cd to the project's rest_queue/src directory, install the required Python add-on modules using:

pip install -r requirements.txt

Then run the server using uvicorn:

uvicorn rest_queue:app --port 8001

You can open a browser to http://localhost:8001/docs#/ to interact with the new queue.

Docker

The docker directory includes a Dockerfile to simplify creating a rest_queue running in a Docker container. cd to this project's docker directory, and run the following commands to build, run, stop, start, and delete the rest_queue docker image and container.

# build image
docker build -t rest_queue:latest .

# start container mapping port 18000 to container port 8000
docker run -d -p 18000:8000 --name rest_queue rest_queue

# stop running container
docker stop rest_queue

# start stopped container
docker start rest_queue

# view running containers
docker ps

# delete container
docker rm rest_queue

# view docker images
docker images

# delete image
docker rmi rest_queue

Open a browser to http://localhost:18000/docs#/ to interact with the new queue.