Writing micro-services in Python... Sure!
But which framework

By Emmanuelle Delescolle

Who am I?

Why this talk?

Why micro-services?

  • You probably don't need microservices
  • But what if you have no choice
    (or do actually need them)

What do I want?
(as developer)

  • Good documentation
  • Good eco-system (doesn't have to be large)
  • Easy switch between environments (dev, prod, etc...)
  • Shell access
  • Auto-documentation of endpoints
  • Browsable API
  • Common project architecture

What do I want?
(as sysadmin/dev-op)

  • Good documentation
  • Common tooling / software
  • Managed processes
  • Logging
  • Easy switch between environment
  • Hot reload

What do I want?
(as product owner)

  • Widespread framework
  • Good documentation
  • Common project architecture
  • No bikeshedding
  • Some performance
  • Documented API's (contracts)
  • Testing


Simple webshop - SQLite DB - OAuth2 - behind Nginx.



  • addition (no auth - no db)
  • catalog (no auth - db)
  • authentication (local auth - db)
  • order creation (remote auth - db)



Flask - Nothing included

  • "Freeform" (not opinionated)
  • No boilerplate
  • Wide and somewhat scattered ecosystem
  • (started as a joke)
  • Preferred SQLAlchemy - OAuth2


Pyramid - Hand-crank included

  • "Freeform"
  • More structured than flask
  • Good documentation
  • Wide ecosystem
  • Preferred SQLAlchemy - (recently) OAuth2


Django - Batteries included
(requires special charger)

  • Opinionated (very)
  • Good documentation
  • Wide eco-system
  • Own ORM
  • Own auth (but works with OAuth2)


FastAPI - Solar panel included

  • Young
  • Opinionated
  • Good documentation (so far)
  • Async
  • Small ecosystem (but that's ok)
  • Preferred SQLAlchemy - databses?
  • Some Oauth2 over your own code

(My?) Requirements

Documentation / Ecosystem

  • Django wins
  • Flask is a headache
  • Pyramid is Switzerland
  • FastAPI is scarce

Shell access

  • Ok in Django, Flask, Pyramid
  • Missing in FastAPI

Auto-documentation of endpoints /
Browsable API / Contract

  • Out of the box in Django and FastAPI
  • API NOT browsable in FastAPI
  • Easy in Pyramid
  • Fastidious in Flask

Testing framework

  • All are easily testable
  • Only Django "pushes" you to write tests

Common project architecture

  • Not much choice in Django
  • A bit more choices in Pyramid
  • Flask and FastAPI let you go all directions


Common tooling / Software,
Managed processes
& Hot reload

  • Django, Flask and Pyramid are WSGI apps (common)
  • uWSGI provides process management + hotreload
  • FastAPI is ASGI (not common yet)
  • Need for supervisor (no hot-reload)


  • Standard python logging
  • Some documentation better than others
  • Different packages available for most frameworks

Easy switch between environments

  • Pyramid wins
  • Flask has something
  • Django has something else
  • FastAPI... not yet


  • There will be some... Train your humans
  • The more opinionated, the less room for bikeshedding
  • Surprisingly lots of room for bikeshedding with FastAPI

Performance... On a pi!

Tested using Locust and htop

Performance... On a pi!

  • Between 350-400 RPS
  • FastAPI uses about 50% less CPU
  • Django uses the less RAM

No DB - No Auth

Performance... On a pi!


  • ~125 RPS (not for FastAPI)
  • Limited by Sqlite
  • Django uses the less RAM
  • FastAPI seems very slow (65 RPS) - seemed to fare better on a desktop - databases?

Performance... On a pi!

Auth and more

  • <100 RPS
  • Limited by network overhead/speed?
  • FastAPI fares good with requests
  • Django doesn't use more RAM



Come to the workshop on Sunday!


Writing micro-services in Python... Sure! But which framework? (talk)

By Emma

Writing micro-services in Python... Sure! But which framework? (talk)

PyCon UK 2019 talk

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