AWS Mailer Go Example

aws_mailer.go

package mailer

import (
	"bytes"
	"fmt"
	"log"
	"os"
	"text/template"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/aws/session"
	"github.com/aws/aws-sdk-go/service/ses"
	"gopkg.in/yaml.v3"
)

const (
	CharSet = "UTF-8"
)

type Mailer struct {
	client *ses.SES
	config ConfMail
}

func (m *Mailer) SendEmail(email string, pin string) {
	htmlBody := templateParse(m.config.HtmlBody, email, pin)
	textBody := templateParse(m.config.TextBody, email, pin)
	input := &ses.SendEmailInput{
		Destination: &ses.Destination{
			CcAddresses: []*string{},
			ToAddresses: []*string{
				aws.String(email),
			},
		},
		Message: &ses.Message{
			Body: &ses.Body{
				Html: &ses.Content{
					Charset: aws.String(CharSet),
					Data:    aws.String(htmlBody),
				},
				Text: &ses.Content{
					Charset: aws.String(CharSet),
					Data:    aws.String(textBody),
				},
			},
			Subject: &ses.Content{
				Charset: aws.String(CharSet),
				Data:    aws.String(m.config.Subject),
			},
		},
		Source: aws.String(m.config.Sender),
	}

	result, err := m.client.SendEmail(input)
	if err != nil {
		if aerr, ok := err.(awserr.Error); ok {
			switch aerr.Code() {
			case ses.ErrCodeMessageRejected:
				fmt.Println(ses.ErrCodeMessageRejected, aerr.Error())
			case ses.ErrCodeMailFromDomainNotVerifiedException:
				fmt.Println(ses.ErrCodeMailFromDomainNotVerifiedException, aerr.Error())
			case ses.ErrCodeConfigurationSetDoesNotExistException:
				fmt.Println(ses.ErrCodeConfigurationSetDoesNotExistException, aerr.Error())
			default:
				fmt.Println(aerr.Error())
			}
		} else {
			fmt.Println(err.Error())
		}

		return
	}

	fmt.Println("Email Sent to address: " + email)
	fmt.Println(result)
}

func loadConfMail() ConfMail {
	data, err := os.ReadFile("mailconf.yaml")
	if err != nil {
		log.Fatalln(err)
	}
	conf := ConfMail{}
	err = yaml.Unmarshal(data, &conf)
	if err != nil {
		log.Fatalln(err)
	}

	return conf
}

func templateParse(body string, email string, pin string) string {
	entry := &Entry{
		Email: email,
		Pin:   pin,
	}
	tmpl, err := template.New("t1").Parse(body)
	if err != nil {
		panic(err)
	}

	var buf bytes.Buffer
	err = tmpl.Execute(&buf, &entry)
	if err != nil {
		panic(err)
	}
	return buf.String()
}

func NewMailer() *Mailer {
	sess, err := session.NewSession(&aws.Config{
		Region: aws.String("eu-west-1")},
	)

	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	svc := ses.New(sess)
	config := loadConfMail()

	return &Mailer{
		client: svc,
		config: config,
	}
}