🚀 Fast Priority Queue 🔥

A minimal priority queuing gateway built with FastAPI using Redis.

It is designed to sit between your clients and a backend REST API, managing two priority levels—high and low—using the rq package. Requests are enqueued based on the request path and processed synchronously by dedicated worker processes, so the overall throughput is limited by the number of workers.

Overview

• Intercepts incoming client requests and forwards them to a target REST API.
• Enqueues requests into either a high-priority or low-priority queue based on configurable path matching.
• Processes queued requests via worker processes running in a separate environment.
• Pass through to /docs and /redoc endpoints with openapi.json definitions of target REST API
• Offers Dockerized deployment for both the gateway and worker processes.

Configuration ⚙️

Both the gateway and workers are fully configurable via the following environment variables.

Gateway

ENV	Description	Required	Default
FAST_PRIORITY_TARGET_BASE_URL	Base url of the target REST api which should run behind the gateway	x
FAST_PRIORITY_HIGH_PRIO_PATHS	Switch between listed and unlisted modes. If listed (unlisted) the paths defined in the PATH env variables are put on the high (low) queue		unlisted
FAST_PRIORITY_PRIO_PATHS	Comma separated list of paths on the target API that should have low priority. Low priority for exact matches		None
FAST_PRIORITY_PRIO_BASE_PATHS	Comma separated list of paths on the target API that should have low priority. Low priority if a request paths starts with the value.		None
FAST_PRIORITY_PASS_THROUGH	Comma separated list of paths on the target API that should skip the queue. Request will be directly be passed on.		health/
FAST_PRIORITY_POLL_INTERVAL	How often should each request check if the job is finished		1.0
FAST_PRIORITY_TTL	Time-to-live (in seconds) for jobs on the queues.		300
FAST_PRIORITY_REDIS_HOST	Redis host		localhost
FAST_PRIORITY_REDIS_PORT	Redis port		6379
FAST_PRIORITY_REDIS_USER	Redis username		None
FAST_PRIORITY_REDIS_PASSWORD	Redis password		None
FAST_PRIORITY_DOC_PATH	Endpoint for the openapi /docs enpoint of the gateway		/gateway_docs
FAST_PRIORITY_REDOC_PATH	Endpoint for the openapi /redoc enpoint of the gateway		/gateway_redoc
FAST_PRIORITY_HEALTH_PATH	Endpoint for the healts check of the gateway		/gateway_health

Queue worker (docker)

ENV	Description	Required	Default
FAST_PRIORITY_WORKERS	Set (e.g., non-empty or a number) to run as a worker instead of the gateway. Controls the number of worker processes to launch.	x
FAST_PRIORITY_REDIS_HOST	Redis host		localhost
FAST_PRIORITY_REDIS_PORT	Redis port		6379
FAST_PRIORITY_REDIS_USER	Redis username		None
FAST_PRIORITY_REDIS_PASSWORD	Redis password		None

Usage

Fast Priority Queue is designed to run via Docker (or Docker Compose) or using the script installed with the package run-fast-priority. The configuration works the same for both approaches using the environment variables described in Configuration section. The script is mainly provide to give the user the flexibility to include the gateway in their own docker containers by installing the package via pypi.

For development (or more specialized application) the gateway can also be run using the underlying command like this:

fastapi run fast_priority/app.py --host 0.0.0.0 --port 8001
rq worker high low

Docker 🐳

You can build the Docker container using the provided Dockerfile. The container adapts its run mode based on the presence of the environment variable FAST_PRIORITY_WORKER:

• If FAST_PRIORITY_WORKER is set, the container starts the worker(s).
• If not, the gateway is started.

The same strategy can be used with you own container and installing the package in the Dockerfile from pypi.

Examples

# API
docker run -p 8010:8000 -e FAST_PRIORITY_TARGET_BASE_URL=http://localhost:8011 -e FAST_PRIORITY_REDIS_HOST=localhost fast_priority:latest

# Workers
docker run -p 8010:8000 -e  FAST_PRIORITY_WORKER=1 -e FAST_PRIORITY_REDIS_HOST=localhost fast_priority:latest

Compose 🐳🐳🐳

The simplest way to run Fast Priority Queue and its dependencies is via Docker Compose. Below is an example configuration:

services:
  behind_gateway_api:
    ...
  priorityity-gateway:
    image: fast_priority:latest
    environment:
      - FAST_PRIORITY_TARGET_BASE_URL=http://behind_gateway_api:8000
      - FAST_PRIORITY_REDIS_HOST=queue
      - FAST_PRIORITY_PRIO_PATHS=endpoint_1,endpoint_2
    ports:
      - 8066:8000

  priority-gateway-worker:
    image: fast_priority:latest
    environment:
      - FAST_PRIORITY_WORKERS=1
      - FAST_PRIORITY_REDIS_HOST=queue
    networks:
      - default
  queue:
    image: redis
    networks:
      - default

networks:
  default:
    driver: bridge

Contributing

Contributions to Fast Priority Queue are welcome! Feel free to open issues or submit pull requests with improvements, bug fixes, or feature suggestions.