Custom OpenFaaS Templates

This repository contains templates for OpenFaaS which I use for my OpenFaaS functions.

$ faas-cli template pull https://github.com/retgits/of-templates
$ faas-cli new --list

Languages available as templates:
- gomods-http
- go-arti-http

gomods-http

The template gomods-http is equivalent to golang-http with the exception being this template uses Go modules and the Go 1.12.5

go-arti-http

The template go-arti-http is equivalent to gomods-http with the exception being this template uses JFrog Artifactory to resolve Go modules. If you need an Artifactory instance yo try it out, you can use JFrog's testdrive and get a four-day triel of both Artifactory and Xray.

Status of the templates

The template is customized to suit my needs, though if you have any thoughts or suggestions, I'd love to hear them.

Just like the golang-http template, this template makes use of the OpenFaaS incubator project of-watchdog.

Trying the templates

$ faas-cli template pull https://github.com/retgits/of-templates
$ faas-cli new --lang <template> <fn-name>

The above commands will create a folder with the name of your function and a set of files:

.
├── go.mod
├── go.sum
└── handler.go

You can change the name of your package by updating the name in the go.mod file. The build template will automatically pick up the correct name when building an OpenFaaS function. It is important that you keep the package function declaration at the top of handler.go.

When using the go-arti-http template, you'll need to set a few build-args for it to work.

# The command
faas-cli build -f stacks.yml -b APP_VERSION=<version of your app> -b APP_NAME=<name of your app> -b ARTIFACTORY_URL=<artifactory host> -b ARTIFACTORY_USER=<artifactory user> -b ARTIFACTORY_PASSWD=<artifactory password>

The build automatically creates a buildInfo in Artifactory and publishes the dependencies in case they do not yet exist.

Example usage

The below samples are from the OpenFaaS repository.

Example writing a successful message:

package function

import (
	"fmt"
	"net/http"

	"github.com/openfaas-incubator/go-function-sdk"
)

// Handle a function invocation
func Handle(req handler.Request) (handler.Response, error) {
	var err error

	message := fmt.Sprintf("Hello world, input was: %s", string(req.Body))

	return handler.Response{
		Body:       []byte(message),
    }, err
}

Example writing a custom status code

package function

import (
	"fmt"
	"net/http"

	"github.com/openfaas-incubator/go-function-sdk"
)

// Handle a function invocation
func Handle(req handler.Request) (handler.Response, error) {
	var err error

	return handler.Response{
		Body:       []byte("Your workload was accepted"),
		StatusCode: http.StatusAccepted,
	}, err
}

Example writing an error / failure.

package function

import (
	"fmt"
	"net/http"

	"github.com/openfaas-incubator/go-function-sdk"
)

// Handle a function invocation
func Handle(req handler.Request) (handler.Response, error) {
	var err error

	return handler.Response{
        Body: []byte("the input was invalid")
	}, fmt.Errorf("invalid input")
}

The error will be logged to stderr and the body will be written to the client along with a HTTP 500 status code.

Example reading a header.

package function

import (
	"log"

	"github.com/openfaas-incubator/go-function-sdk"
)

// Handle a function invocation
func Handle(req handler.Request) (handler.Response, error) {
	var err error

	log.Println(req.Header) // Check function logs for the request headers

	return handler.Response{
		Body: []byte("This is the response"),
		Header: map[string][]string{
			"X-Served-By": []string{"My Awesome Function"},
		},
	}, err
}

retgits / of-templates