fn-serverless/examples/tutorial/hello/python

Tutorial 1: Python Function w/ Input (3 minutes)

This example will show you how to test and deploy Python code to Fn. It will also demonstrate passing data in through stdin.

First, run the following commands:

# Initialize your function creating a func.yaml file
fn init --name hello-python

# Test your function. 
# This will run inside a container exactly how it will on the server. It will also install and vendor dependencies from Gemfile
fn run

# Now try with an input
cat sample.payload.json | fn run

# Deploy your functions to the Fn server (default localhost:8080)
# This will create a route to your function as well
fn deploy --app myapp

Now call your function:

curl http://localhost:8080/r/myapp/python

Or call from a browser: http://localhost:8080/r/myapp/python

And now with the JSON input:

curl -H "Content-Type: application/json" -X POST -d @sample.payload.json http://localhost:8080/r/myapp/python

That's it! Our fn deploy packaged our function and sent it to the Fn server. Try editing func.py and then doing another fn deploy.

Note on Dependencies

In Python, we create a requirements file in your function directory then fn deploy will build and deploy with these dependencies.

In Review

1. We piped JSON data into the function at the command line

   cat sample.payload.json | fn run
   

2. We received our function input through stdin

   obj = json.loads(sys.stdin.read())
   

3. We wrote our output to stdout

   print "Hello", name, "!"
   

4. We sent stderr to the server logs

   sys.stderr.write("Starting Python Function\n")
   

Next Up

Part 2: Input Parameters