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package main
import (
"bytes"
"context"
"fmt"
"image"
"image/jpeg"
"io"
"strings"
"github.com/aws/aws-lambda-go/events"
"github.com/aws/aws-lambda-go/lambda"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/s3"
"github.com/disintegration/imaging"
)
func main() {
lambda.Start(handler)
}
func handler(ctx context.Context, s3Event events.S3Event) error {
sess, err := session.NewSession(&aws.Config{
// Tokyo region is ap-northeast-1
Region: aws.String("ap-northeast-1")},
)
if err != nil {
// check error, lambda logs also show up in cloudwatch
fmt.Println("message: error = ", err.Error())
return err
}
svc := s3.New(sess)
fmt.Println("message: get session")
// only deal with one file at a time
object := s3Event.Records[0].S3.Object
// key is the file name with all prefix
key := object.Key
// bucket is the bucket name
bucket := "{Your Bucket Name}"
// check the file key
fmt.Println("message: key = ", key)
resp, err := svc.GetObject(&s3.GetObjectInput{
Bucket: aws.String(bucket),
Key: aws.String(key),
})
if err != nil {
fmt.Println("message: error = ", err.Error())
return err
}
defer resp.Body.Close()
content, err := io.ReadAll(resp.Body)
if err != nil {
fmt.Println("message: error = ", err.Error())
return err
}
img, _, err := image.Decode(bytes.NewReader(content))
if err != nil {
fmt.Println("message: error = ", err.Error())
return err
}
resized := imaging.Resize(img, 3000, 3000, imaging.Lanczos)
buf := new(bytes.Buffer)
err = jpeg.Encode(buf, resized, nil)
if err != nil {
fmt.Println("message: error = ", err.Error())
return err
}
// get the file name with prefix
keyPath := strings.Split(key, "/")
imageName := keyPath[len(keyPath)-1]
// put the new resized image to the another folder, avoid infinite loop
newKey := "/podcast/images/" + imageName
_, err = svc.PutObject(&s3.PutObjectInput{
Bucket: aws.String(bucket),
Key: aws.String(newKey),
ContentType: aws.String("image/jpeg"),
Body: bytes.NewReader(buf.Bytes()),
})
if err != nil {
fmt.Println("message: error = ", err.Error())
return err
}
fmt.Println("message: success")
return nil
}
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