AWS lambda使用案例——为S3中图片生成缩略图

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主要是其试验经过。

 

Task1：创建两个S3

命名分别为images-NUMBER，  images-NUMBER-resized

找到一张大图，名为HappyFace.jpg，上传到images-NUMBER

https://s3.us-west-2.amazonaws.com/us-west-2-aws-training/awsu-spl/spl-88/2.3.7.prod/images/HappyFace.jpg

 

Task2：创建lambda函数

默认设置，填写名称Create-Thumbnail，Runtime：python3.7

在Choose or create an execution role中选择

Execution role：Using an existing role

Existing role:lambda-execution-role

这个role会给lambda函数访问和读写S3的权限

点击Add trigger，选择trigger:s3，Bucket选择images-NUMBER，EventType为all object create events然后Add

图中点击Create-Thumbnail，代码里选择upload a file from s3

https://s3-us-west-2.amazonaws.com/us-west-2-aws-training/awsu-spl/spl-88/2.3.7.prod/scripts/CreateThumbnail.zip

它的意思是

import boto3
import os
import sys
import uuid
from PIL import Image
import PIL.Image

s3_client = boto3.client('s3')

def resize_image(image_path, resized_path):
    with Image.open(image_path) as image:
        image.thumbnail((128, 128))
        image.save(resized_path)

def handler(event, context):
    for record in event['Records']:
        bucket = record['s3']['bucket']['name']
        key = record['s3']['object']['key']
        download_path = '/tmp/{}{}'.format(uuid.uuid4(), key)
        upload_path = '/tmp/resized-{}'.format(key)

        s3_client.download_file(bucket, key, download_path)
        resize_image(download_path, upload_path)
        s3_client.upload_file(upload_path, '{}-resized'.format(bucket), key)

在Basic settings中，编辑

Description：Create a thumbnail-sized image

Handler：CreateThumbnail.handler

保存。Lambda函数至此已配置好。

 

Task3：测试lambda函数

点击上方Test按钮，配置

Event template：搜索“Amazon S3 Put“

Event name：Upload

在下方代码中替换example-bucket的两处内容为images-NUMBER。

替换test/key的一处，为HappyFace.jpg

点击Create。随后开始Test

在images-NUMBER-resized查看新图片。

<完>

 

附：

AWS Lambda文档：https://docs.aws.amazon.com/lambda/index.html