Deploy a serverless flask app on aws lambda


Serverless is the new buzz word right now, what does it really means? Serverless computing allows us to focus on building the application without managing infrastructure and scaling. Serverless doesn’t mean no servers at all. It is still there, but we are not going to manage it. The best part is that you only pay for the amount of resources each request consumed. Each request to the serverless function is run in a stateless container.

Advantages: * Horizontally scalable * Pay for what you use * Infrastructure managed by service provider

AWS Lambda

AWS provides serverless service called “Lambda” which can be used to deploy and run serverless applications. AWS lambda lets us run any Python WSGI based applications on cloud. It To make this tutorial easier, we are going to use an popular opensource serverless framework called “Zappa” and run “Flask” application on aws lambda.


  • experience on AWS
  • python 3

Install dependancies

pip install Flask zappa

Setup AWS Account

Create an user in IAM with administrative access and create api key and password. You will need this when you create zappa project.

Create Flask application

from flask import Flask
app = Flask(__name__)

def hello():
    return "Hello World!"

Initialize zappa project

zappa init

finally zappa_settings.json will look like this,

    "dev": {
        "app_function": "",
        "aws_region": "<aws_region>",
        "profile_name": "<aws_profile>", // profile config at ~/.aws/credentials
        "project_name": "serverless-bot",
        "runtime": "python3.6",
        "s3_bucket": "serverless-bot"

Deploy to AWS Lambda

zappa deploy dev

Zappa deploy process will automatically generate an web accessible url of the flask application.

Deploy Latest Build to AWS Lambda

When you update your flask application code, zappa has a command to update aws lambda deployment.

zappa update dev