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AWS Chalice

AWS Chalice is a serverless micro framework used to develop and deploy your serverless applications on AWS resources. Chalice provides integrated functionality with most of the AWS Toolings like S3 Storage, Simple Queue Service, API Gateway and more. It offers a handy CLI interface that allows you to easily create, develop & deploy your serverless applications.

LocalStack offers an AWS Chalice client that allows you to interact with your Chalice applications locally. Using LocalStack, you can kick-start your development process, create a new Chalice application, and test it application locally.

Start LocalStack inside a Docker container by running:

Terminal window
localstack start -d

Install the chalice-local package by running:

Terminal window
pip install chalice-local

You can now create a new Chalice project by running:

Terminal window
chalice-local new-project

You will be prompted with an interactive menu where you can choose the name of your project and the project type. In this example, we are using localstack-test as the project name and REST API as the project type:

Terminal window
___ _ _ _ _ ___ ___ ___
/ __|| || | /_\ | | |_ _|/ __|| __|
| (__ | __ | / _ \ | |__ | || (__ | _|
\___||_||_|/_/ \_\|____||___|\___||___|
The python serverless microframework for AWS allows
you to quickly create and deploy applications using
Amazon API Gateway and AWS Lambda.
Please enter the project name
[?] Enter the project name: localstack-test
[?] Select your project type: REST API
> REST API
S3 Event Handler
Lambda Functions only
Legacy REST API Template
[CDK] Rest API with a DynamoDB table
Your project has been generated in ./localstack-test

Let’s take a look inside the project structure:

  • app.py
  • Directorychalicelib
    • __init__.py
  • requirements-dev.txt
  • requirements.txt
  • Directorytests
    • __init__.py
    • test_app.py

The app.py is our main API file. It has only one Route that would assign the URL of the application to the function. The decorators here primarily “wrap” functions here which makes it easy to write Code Logic by breaking them down into separate routes. For now, our Application is serving only a JSON Message which is {'hello': 'world'}.

Just as with AWS, you can now test your API using chalice-local local:

Terminal window
chalice-local local
Serving on http://127.0.0.1:8000

You can also do a curl to test the API:

Terminal window
curl -X GET http://127.0.0.1:8000
{"hello":"world"}

You can use chalice-local deploy to deploy the REST API now:

Terminal window
chalice-local deploy
Creating deployment package.
Creating IAM role: localstack-test-dev
Creating lambda function: localstack-test-dev
Creating Rest API
Resources deployed:
- Lambda ARN: arn:aws:lambda:us-east-1:000000000000:function:localstack-test-dev
- Rest API URL: https://y5iuni004m.execute-api.us-east-1.amazonaws.com/api/

We now have our Chalice Application deployed on a Lambda Amazon Resource Name (ARN) along with a REST API URL.