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Asynchronous Server App Boilerplate (ASAB) is a micro-service framework for Python 3 and asyncio.


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Asynchronous Server App Boilerplate

Asynchronous Server App Boilerplate (or ASAB for short) is a microservice framework for Python 3 and asyncio. The aim of ASAB is to minimize the amount of code that needs to be written when building a microservice or an aplication server. ASAB is fully asynchronous using async/await syntax from Python 3, making your code modern, non-blocking, speedy and hence scalable. We make every effort to build ASAB container-friendly so that you can deploy ASAB-based microservice via Docker or Kubernetes in a breeze.

ASAB is the free and open-source software, available under BSD licence. It means that anyone is freely licenced to use, copy, study, and change the software in any way, and the source code is openly shared so that people could voluntarily improve the design of the software. Anyone can (and is encouraged to) use ASAB in his or her projects, for free.

ASAB is currently used for microservices, web application servers, ETL or stream processors.

ASAB is developed on GitHub. Contributions are welcome!


$ pip install asab



#!/usr/bin/env python3

class MyApplication(asab.Application):

    def __init__(self):

        # Create the Web server
        web = asab.web.create_web_server(self)

        # Add a route to the handler method
        web.add_get('/hello', self.hello)

    # This is the web request handler
    async def hello(self, request):
        return, data="Hello, world!\n")

if __name__ == '__main__':
    # Create and start the application
    app = MyApplication()

The application is available at http://localhost:8080/. You can test it by:

$ curl http://localhost:8080/hello


Here is a growing list of Open Source microservices built using ASAB:

  • ASAB Iris: document rendering, sends output using email, SMS and instant messaging
  • SeaCat Auth: authentication, authorization, identity management, session management and other access control features


  • Unified approach to Configuration
  • Logging using reasonably configured Python logging module
  • Build-in and custom Metrics with feeds into InfluxDB and Prometheus
  • Alerting with integration to PagerDuty and OpsGenie.
  • HTTP Server powered by aiohttp library
  • Apache Zookeeper Client provides shared consensus across microservices’ cluster
  • Persistent storage abstraction based on upsertor for MongoDB and ElasticSearch
  • Pub/Sub
  • Dependency injection using Modules and Services
  • Proactor pattern service for long-running synchronous work
  • Task service
  • Unified microservice API

Automatic API documentation

The REST API is automatically documented using OpenAPI3 standard and the Swagger.


  • Write once, use many times
  • Keep it simple
  • Well documented
  • Asynchronous via Python 3 async/await and asyncio
  • Event-driven Architecture / Reactor pattern
  • Single-threaded core but compatible with threads
  • First-class support for containerization
  • Compatible with pypy, Just-In-Time Python compiler
  • Kappa architecture
  • Support for introspection
  • Modularized

Video tutorial


ASAB is an open-source software, available under BSD 3-Clause License. ASAB is maintained by TeskaLabs Ltd.