README.md

Hello

This is a Hello World example using OpenFaaS R templates.

You will learn how to make a function that uses POST request passing info from the request body, then modify it to a GET request using URL parameters.

You'll need the prerequisites listed here.

• Hello
  • Create a new function using a template
  • Build, push, deploy the function
  • Testing
  • Customize the function

Create a new function using a template

Create a new function called r-hello.

faas-cli new --lang rstats-base-plumber r-hello

We don't need to edit the function further because the template contains the Hello World example.

Build, push, deploy the function

faas-cli up is a shorthand for automating faas-cli build, faas-cli push, and faas-cli deploy.

faas-cli up -f r-hello.yml

Testing

Test the Docker image locally after docker run -p 5000:8080 $OPENFAAS_PREFIX/r-hello:

curl http://localhost:5000/ -d '"World"'

Test the deployed instance:

curl $OPENFAAS_URL/function/r-hello -d '"World"'

The output should be "Hello World!".

Customize the function

Edit the ./r-hello/handler.R file:

#* Hello
#* @serializer unboxedJSON
#* @get /
function(name) {
  paste0("Hello ", name, "!")
}

This will use a parameter from the URL instead of parsing the request body.

Note: we have changed the function argument (from req to name) and the HTTP request method from @post to @get.

Build, push, deploy the function:

faas-cli up -f r-hello.yml

Test the Docker image locally after docker run -p 5000:8080 $OPENFAAS_PREFIX/r-hello:

curl http://localhost:5000/?name=World

Test the deployed instance (we have to pass parameters as data using -G):

curl -X GET -G \
  $OPENFAAS_URL/function/r-hello \
  -d name=World

The output should still be "Hello World!".