Section 0: Introduction to AWS Chalice

This section will provide an introduction on how to use AWS Chalice and provide instructions on how to go about building your very first Chalice application.

Create a virtualenv and install Chalice

To start using Chalice, you will need a new virtualenv with Chalice installed.

Instructions

Make sure you have Python 3 installed. See the env-setup page for instructions on how to install Python.

  1. Create a new virtualenv called chalice-env by running the following command:

    $ python3 -m venv chalice-env

  2. Activate your newly created virtualenv:

    $ source chalice-env/bin/activate

    If you are using a Windows environment, you will have to run:

    > .\chalice-env\Scripts\activate

  3. Install chalice using pip:

    $ pip install chalice

Verification

To check that chalice was installed, run:

$ chalice --version

This should print out the version of chalice that is installed in your virtualenv.

Also, ensure that Python 3.7 is being used as the Python interpreter for your virtualenv:

$ python --version
Python 3.7.3

Create a new Chalice application

With chalice now installed, it is time to create your first Chalice application.

Instructions

  1. Run the chalice new-project command to create a project called workshop-intro:

    $ chalice new-project workshop-intro

Verification

A new workshop-intro directory should have been created on your behalf. Inside of the workshop-intro directory, you should have two files: an app.py file and a requirements.txt file:

$ ls workshop-intro
app.py           requirements.txt

Deploy the Chalice application

The newly created Chalice application can also be immediately deployed. So let’s deploy it.

Instructions

  1. Change directories to your newly created workshop-intro directory:

    $ cd workshop-intro

  2. Run chalice deploy to deploy your Chalice application:

    $ chalice deploy
Creating deployment package.
Creating IAM role: workshop-intro-dev
Creating lambda function: workshop-intro-dev
Creating Rest API
Resources deployed:
  - Lambda ARN: arn:aws:lambda:us-west-2:12345:function:workshop-intro-dev
  - Rest API URL: https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

Verification

The chalice deploy command should have exited with a return code of 0:

$ echo $?
0

You should also be able to interact with your newly deployed API. To do so, first install httpie:

$ pip install httpie

Get the endpoint of your deployed Chalice application with chalice url:

$ chalice url
https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

Now use httpie to make an HTTP request to that endpoint:

$ http https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 18
Content-Type: application/json
Date: Sat, 21 Oct 2017 23:21:41 GMT
Via: 1.1 403d925786ea6bd8903b99a628977c8f.cloudfront.net (CloudFront)
X-Amz-Cf-Id: FlL4RfE3UqiDFocyTlSzCqtvzxWd9pK0M1lCnIsO1KwjhF37XvVTCg==
X-Amzn-Trace-Id: sampled=0;root=1-59ebd683-72e3a6105ff3425da0c7e0ae
X-Cache: Miss from cloudfront
x-amzn-RequestId: 9776fca3-b6b6-11e7-94e4-b130a115985d

{
    "hello": "world"
}

The HTTP response back should consist of the JSON body: {"hello": "world"}

Add a new route

Now that we have deployed our first Chalice application, let’s expand on it by adding a new /hello route.

Instructions

  1. Open the app.py file in your favorite editor:

    $ vim app.py

  2. Inside of the app.py file, add the following function under the existing index() function:

    @app.route('/hello')
def hello_workshop():
    return {'hello': 'workshop'}

    Your app.py should now consist of the following:

    from chalice import Chalice

app = Chalice(app_name='workshop-intro')


@app.route('/')
def index():
    return {'hello': 'world'}

@app.route('/hello')
def hello_workshop():
    return {'hello': 'workshop'}

  3. Deploy the updated application using chalice deploy:

    $ chalice deploy
Creating deployment package.
Updating policy for IAM role: workshop-intro-dev
Updating lambda function: workshop-intro-dev
Updating rest API
Resources deployed:
  - Lambda ARN: arn:aws:lambda:us-west-2:12345:function:workshop-intro-dev
  - Rest API URL: https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

Validation

Using httpie, confirm that the new route was deployed by making an HTTP request:

$ http https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/hello
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 21
Content-Type: application/json
Date: Sat, 21 Oct 2017 23:34:56 GMT
Via: 1.1 2d8af5cc5befc5d35bb54b4a5b6494c9.cloudfront.net (CloudFront)
X-Amz-Cf-Id: upMVSIUvjmCRa33IO-4zpYQOU0C94h50F3oJX_iv-vdk-g1IacKq9A==
X-Amzn-Trace-Id: sampled=0;root=1-59ebd9a0-0a275c8f6794f2e5c59641c7
X-Cache: Miss from cloudfront
x-amzn-RequestId: 7233e21a-b6b8-11e7-a3b6-f7221d70ee14

{
    "hello": "workshop"
}

The HTTP response back should consist of the JSON body: {"hello": "workshop"}

Add a new route with a URI parameter

Next, let’s add a new route that accepts a parameter in the URI.

Instructions

  1. Inside of the app.py file, add the following function under the existing hello_workshop() function:

    @app.route('/hello/{name}')
def hello_name(name):
    return {'hello': name}

    Your app.py should now consist of the following:

    from chalice import Chalice

app = Chalice(app_name='workshop-intro')


@app.route('/')
def index():
    return {'hello': 'world'}

@app.route('/hello')
def hello_workshop():
    return {'hello': 'workshop'}

@app.route('/hello/{name}')
def hello_name(name):
    return {'hello': name}

  2. Deploy the updated application using chalice deploy:

    $ chalice deploy
Creating deployment package.
Updating policy for IAM role: workshop-intro-dev
Updating lambda function: workshop-intro-dev
Updating rest API
Resources deployed:
  - Lambda ARN: arn:aws:lambda:us-west-2:12345:function:workshop-intro-dev
  - Rest API URL: https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

Verification

Using httpie, confirm that the new route was deployed by making an HTTP request:

$ http https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/hello/kyle
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 21
Content-Type: application/json
Date: Sat, 21 Oct 2017 23:34:56 GMT
Via: 1.1 2d8af5cc5befc5d35bb54b4a5b6494c9.cloudfront.net (CloudFront)
X-Amz-Cf-Id: upMVSIUvjmCRa33IO-4zpYQOU0C94h50F3oJX_iv-vdk-g1IacKq9A==
X-Amzn-Trace-Id: sampled=0;root=1-59ebd9a0-0a275c8f6794f2e5c59641c7
X-Cache: Miss from cloudfront
x-amzn-RequestId: 7233e21a-b6b8-11e7-a3b6-f7221d70ee14

{
    "hello": "kyle"
}

The HTTP response back should consist of the JSON body: {"hello": "kyle"}

Add a new route with a non-GET HTTP method

For our last route, let’s add a new route that accepts a different HTTP method other than GET.

Instructions

  1. Inside of the app.py file, add the following function under the existing hello_name() function:

    @app.route('/hello-post', methods=['POST'])
def hello_post():
    request_body = app.current_request.json_body
    return {'hello': request_body}

    Your app.py should now consist of the following:

    from chalice import Chalice

app = Chalice(app_name='workshop-intro')


@app.route('/')
def index():
    return {'hello': 'world'}

@app.route('/hello')
def hello_workshop():
    return {'hello': 'workshop'}

@app.route('/hello/{name}')
def hello_name(name):
    return {'hello': name}

@app.route('/hello-post', methods=['POST'])
def hello_post():
    request_body = app.current_request.json_body
    return {'hello': request_body}

  2. Deploy the updated application using chalice deploy:

    $ chalice deploy
Creating deployment package.
Updating policy for IAM role: workshop-intro-dev
Updating lambda function: workshop-intro-dev
Updating rest API
Resources deployed:
  - Lambda ARN: arn:aws:lambda:us-west-2:12345:function:workshop-intro-dev
  - Rest API URL: https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

Verification

Using httpie, confirm that the new route was deployed by making an HTTP request:

$ echo '{"request":"body"}' | http POST https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/hello-post
HTTP/1.1 200 OK
Connection: keep-alive
Content-Length: 30
Content-Type: application/json
Date: Sat, 21 Oct 2017 23:48:43 GMT
Via: 1.1 805232684895bb3db77c2db44011c8d0.cloudfront.net (CloudFront)
X-Amz-Cf-Id: ah7w7to9Svn_WzGZ1MldMHERCO_sLxMKQi9AcHFLSjLtAdAPhw5z_A==
X-Amzn-Trace-Id: sampled=0;root=1-59ebdcdb-32c834bbd0341b40e3dfd787
X-Cache: Miss from cloudfront
x-amzn-RequestId: 5f0bf184-b6ba-11e7-a22d-9b7d2bcfb95b

{
    "hello": {
        "request": "body"
    }
}

Notice the HTTP response back should contain the JSON blob that was echoed into standard input.

Delete the Chalice application

Now with an understanding of the basics of how to use AWS Chalice, let’s clean up this introduction application by deleting it remotely.

Instructions

  1. Run chalice delete to delete the deployed AWS resources running this application:

    $ chalice delete
Deleting Rest API: 1y2mueb824
Deleting function: arn:aws:lambda:us-west-2:12345:function:workshop-intro-dev
Deleting IAM role: workshop-intro-dev

    If you are prompted on whether to delete a resource when deleting the application, go ahead and confirm by entering y.

Verification

To ensure that the API no longer exists remotely, try to make an HTTP request to the endpoint it was originally deployed to:

$ http https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

http: error: SSLError: [SSL: SSLV3_ALERT_HANDSHAKE_FAILURE] sslv3 alert
handshake failure (_ssl.c:590) while doing GET request to URL:
https://1y2mueb824.execute-api.us-west-2.amazonaws.com/api/

This should result in an SSL error as the remote application no longer exists and therefore it cannot be connected to it.