Deploy Golang function on Openfaas

this post will show you how to deploy a Sendtweet golang function in a OpenFaas Plaform.

installation

Openfaas supports Docker swarm, Docker Playground, but here i used Kubernetes environment as example

CentOS 7 Kubernetes Master-Node installation guide

after you deployed your kubernetes, you can start to deploy Openfaas

Openfaas CLI

faas-cli used to manage all of your functions

> curl -sL https://cli.openfaas.com | sudo sh
> faas-cli version
  ___                   _____           ____
 / _ \ _ __   ___ _ __ |  ___|_ _  __ _/ ___|
| | | | '_ \ / _ \ '_ \| |_ / _` |/ _` \___ \
| |_| | |_) |  __/ | | |  _| (_| | (_| |___) |
 \___/| .__/ \___|_| |_|_|  \__,_|\__,_|____/
      |_|

CLI:
 commit:  xxxxxxxxxxxxxx
 version: 0.8.3

Deploy OpenFaas

> git clone https://github.com/openfaas/faas-netes
> kubectl apply -f ./faas-netes/yaml
> kubectl get pods -n openfaas
NAME                            READY   STATUS    RESTARTS   AGE
alertmanager-5df696f54d-ts8jd   1/1     Running   3          1h
gateway-7f4dc7ff46-xzwc5        2/2     Running   12         1h
nats-765f98bd59-n9g85           1/1     Running   3          1h
prometheus-5dfc76b657-w9q9f     1/1     Running   3          1h
queue-worker-7b48d787bb-fhbd8   1/1     Running   10         1h

if there’s nothing wrong, open http://localhost:31112/ you will see the OpenFaas Portal.

Deploy Grafana monitor

> kubectl -n openfaas run --image=stefanprodan/faas-grafana:4.6.3 --port=3000 grafana
> kubectl get pods -n openfaas grafana-595c55957b-7gc54
NAME                       READY   STATUS    RESTARTS   AGE
grafana-595c55957b-7gc54   1/1     Running   1          26h
> kubectl -n openfaas expose deployment grafana --type=NodePort --name=grafana
> echo http://localhost:$(kubectl -n openfaas get svc grafana -o jsonpath="{.spec.ports[0].nodePort}")
http://localhost:31380 # grafana panel

user/pass: admin

Golang function

faas-cli can generates many different languages template

> faas-cli new --lang go sendtweet
Folder: sendtweet created.
  ___                   ___              ___  
 / _ \ _ __   ___ _ __ |  ___|_ _  __ _/ ___| 
| | | | '_ \ / _ \ '_ \| |_ / _` |/ _` \___ \ 
| |_| | |_) |  __/ | | |  _| (_| | (_| |___) |
 \___/| .__/ \___|_| |_|_|  \__,_|\__,_|___ / 
      |_|                                     

Function created in folder: sendtweet
Stack file written: sendtweet.yml

so i wrote a function that use to send tweet

package function

import (
    "encoding/json"
    "errors"

    "github.com/dghubble/go-twitter/twitter"
    oa1 "github.com/dghubble/oauth1"
)

var (
    errValNotExists = errors.New("Consumer key/secret and Access token/secret required")
    errInvalidData  = errors.New("Invalid request data")
)

type req struct {
    ConsumerKey    string `json:"consumer_key"`
    ConsumerSecret string `json:"consumer_secret"`
    AccessToken    string `json:"access_token"`
    AccessSecret   string `json:"access_secret"`
    Msg            string `json:"msg"`
}

func (r *req) getClient() (*twitter.Client, error) {
    if r.ConsumerKey == "" || r.ConsumerSecret == "" || r.AccessToken == "" || r.AccessSecret == "" {
        return nil, errValNotExists
    }
    config := oa1.NewConfig(r.ConsumerKey, r.ConsumerSecret)
    token := oa1.NewToken(r.AccessToken, r.AccessSecret)
    httpClient := config.Client(oa1.NoContext, token)
    return twitter.NewClient(httpClient), nil
}

// Handle a serverless request
func Handle(r []byte) string {
    var request = &req{}
    if ok := json.Unmarshal(r, request); ok != nil {
        return errInvalidData.Error()
    }
    c, err := request.getClient()
    if err != nil {
        return err.Error()
    }
    _, _, err = c.Statuses.Update(request.Msg, nil)
    if err != nil {
        return err.Error()
    }
    return "succssed"
}

deploy it with dependency

> dep init -v # go get -u github.com/golang/dep/cmd/dep
> faas-cli build -f sendtweet.yml
> faas-cli deploy -f sendtweet.yml
> kubectl get pods -n openfaas-fn # `openfaas-fn` all of your functions will running on this namespace
NAME                        READY   STATUS    RESTARTS   AGE
sendtweet-89d4f59f6-jwtjp   1/1     Running   1          1h

Invokes

for synchronized invoke follow http://{domainname}:{port}/function/{function name} to invoke your functions

for synchronized invoke, you have to set a callback url in your request headers, then follow http://{domainname}:{port}/async-function/{function name} to starts your invoke

POST /async-function/sendtweet HTTP/1.1
Host: localhost:31112
X-Callback-Url: http://localhost:3001/callback

{
    "consumer_key": "xxxxx",
    "consumer_secret": "xxxx",
    "access_token": "xxxxx",
    "access_secret": "xxxx",
    "msg": "Hello for testing asynchronous task"
}