Getting started with OpenFaaS and Golang on minikube

Software Engineering
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Set up environment on MacOS

  • brew install go docker-machine-driver-hyperkit faas-cli kubernetes-cli kubernetes-helm
  • brew cask install minikube docker

docker-machine-driver-hyperkit can replace by virtualbox. Use brew cask install virtualbox to install it.

docker-machine-driver-hyperkit and docker both have docker-machine. It may cause some error when homebrew create symbolic link. This error can be ignored since docker-machine will always point to docker’s when starting docker for mac.

Start minikube

Use virtualbox (Default)

  • minikube start

Use hyperkit

  • minikube start --vm-driver=hyperkit

Or use minikube config set vm-driver hyperkit to modify default value.

Deploy OpenFaaS to minikube

  1. Create a service account for Helm’s server component (tiller): kubectl -n kube-system create sa tiller && kubectl create clusterrolebinding tiller --clusterrole cluster-admin --serviceaccount=kube-system:tiller
  2. Install tiller which is Helm’s server-side component: helm init --skip-refresh --upgrade --service-account tiller
  3. Create namespaces for OpenFaaS core components and OpenFaaS Functions: kubectl apply -f https://raw.githubusercontent.com/openfaas/faas-netes/master/namespaces.yml
  4. Add the OpenFaaS helm repository: helm repo add openfaas https://openfaas.github.io/faas-netes/
  5. Update all the charts for helm: helm repo update
  6. Create a password (Remember this for login to OpenFaaS dashboard): export PASSWORD=... Random password example: export PASSWORD=$(head -c 12 /dev/urandom | shasum| cut -d' ' -f1)
  7. Create a secret for the password: kubectl -n openfaas create secret generic basic-auth --from-literal=basic-auth-user=admin --from-literal=basic-auth-password="$PASSWORD"
  8. Install OpenFaaS using the chart: helm upgrade openfaas --install openfaas/openfaas --namespace openfaas --set functionNamespace=openfaas-fn --set basic_auth=true
  9. Finally once all the Pods are started you can login using the faas-cli: echo -n $PASSWORD | faas-cli login -g http://$(minikube ip):31112 -u admin --password-stdin
  10. You can use echo http://$(minikube ip):31112 to find dashboard URL and open it by browser (username: admin)

Use faas-cli

Generate a Go function

  • faas-cli new go-fn --lang go

This command will generate a go-fn directory contains a simple template function response like this “Hello, Go. You said: (request body)” and a go-fn.yml file in working directory.

Build function

  1. Create a Docker Hub account
  2. Add your Docker Hub username to go-fn.yml file’s image tag
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    functions:
      go-fn:
        lang: go
        handler: ./go-fn
        image: USERNAME/go-fn:latest
  3. Build docker image: faas-cli build -f go-fn.yml
  4. Push to Docker Hub: faas-cli push -f go-fn.yml

You can find go-fn in your Docker Hub repository.

Deploy function

  • faas-cli deploy -f go-fn.yml --gateway http://$(minikube ip):31112

Then you can see this function in the dashboard. Invoke it by using dashboard UI or using faas-cli.

  • echo test | faas-cli invoke go-fn --gateway http://$(minikube ip):31112

Build, push and deploy can use just one command to finish these step faas-cli up -f go-fn.yml --gateway http://$(minikube ip):31112

Develop with third-party package using Go module (Go 1.11+)

  1. Init go module in go-fn directory: go mod init PROJECT_NAME
  2. Import some third-party package in handler.go

example:

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package function

import (
	"fmt"

	"gopkg.in/loremipsum.v1"
)

// Handle a serverless request
func Handle(req []byte) string {
	text := loremipsum.New().Words(10)

	return fmt.Sprintf("Request body: %s\nResponse: %s", string(req), string(text))
}
  1. Create vendor directory: go mod vendor (OpenFaaS use vendor to manage dependency)
  2. Build and deploy this new function: faas-cli up -f go-fn.yml --gateway http://$(minikube ip):31112

How to use this example repository

  1. Deploy OpenFaaS
  2. Clone this repository
  3. Create vendor in go-fn directory
  4. Modify yml file’s Docker Hub username in image tag
  5. Deploy function

Reference