OpenFaaS Python Flask Templates

The Python Flask templates that make use of the incubator project of-watchdog.

Templates available in this repository:

python27-flask
python3-flask
python3-flask-armhf
python3-http
python3-http-armhf

Notes:

To build and deploy a function for Raspberry Pi or ARMv7 in general, use the language templates ending in -armhf

Downloading the templates

$ faas template pull https://github.com/openfaas-incubator/python-flask-template

Using the python27-flask/python3-flask templates

Create a new function

$ faas new --lang python27-flask <fn-name>

Build, push, and deploy

$ faas up -f <fn-name>.yml

Test the new function

$ echo -n content | faas invoke <fn-name>

Using the python3-http templates

Create a new function

$ faas new --lang python3-http <fn-name>

Build, push, and deploy

$ faas up -f <fn-name>.yml

Set your OpenFaaS gateway URL. For example:

$ OPENFAAS_URL=http://127.0.0.1:8080

Test the new function

$ curl -i $OPENFAAS_URL/function/<fn-name>

Event and Context Data

The function handler is passed two arguments, event and context.

event contains data about the request, including:

body
headers
method
query
path

context contains basic information about the function, including:

hostname

Response Bodies

By default, the template will automatically attempt to set the correct Content-Type header for you based on the type of response.

For example, returning a dict object type will automatically attach the header Content-Type: application/json and returning a string type will automatically attach the Content-Type: text/html, charset=utf-8 for you.

Example usage

Custom status codes and response bodies

Successful response status code and JSON response body

def handle(event, context):
    return {
        "statusCode": 200,
        "body": {
            "key": "value"
        }
    }

Successful response status code and string response body

def handle(event, context):
    return {
        "statusCode": 201,
        "body": "Object successfully created"
    }

Failure response status code and JSON error message

def handle(event, context):
    return {
        "statusCode": 400,
        "body": {
            "error": "Bad request"
        }
    }

Custom Response Headers

Setting custom response headers

def handle(event, context):
    return {
        "statusCode": 200,
        "body": {
            "key": "value"
        },
        "headers": {
            "Location": "https://www.example.com/"
        }   
    }

Accessing Event Data

Accessing request body

def handle(event, context):
    return {
        "statusCode": 200,
        "body": "You said: " + str(event.body)
    }

Accessing request method

def handle(event, context):
    if event.method == 'GET':
        return {
            "statusCode": 200,
            "body": "GET request"
        }
    else:
        return {
            "statusCode": 405,
            "body": "Method not allowed"
        }

Accessing request query string arguments

def handle(event, context):
    return {
        "statusCode": 200,
        "body": {
            "name": event.query['name']
        }
    }

Accessing request headers

def handle(event, context):
    return {
        "statusCode": 200,
        "body": {
            "content-type-received": event.headers['Content-Type']
        }
    }

mehyedes/python-flask-template