AWS的lambda和S3之间如何连携

　　今天正好遇到了这个问题，就在官方文档里查询，然后根据他的说明整理了一下大致的流程，详细的请参考AWS国际版的官方文档，这里只是作者的一个简单的流程展示。

　　

Lambda和S3连接

1.在S3的同一区域当中创建2个桶

命名规则：source

Sourceresized

2.往source的S3桶中上传一张命名为HappyFace.jpg的文件

3.准备一台安装好node.js的服务器

①创建一个文件夹

mkdir examplefolder

②在这个文件夹路径下创建一个子文件夹

cd examplefolder

mkdir node_modules

③安装插件，在当前路径下

npm install async gm

④安装完毕，创建一个文件index.js

touch index.js

⑤打开index.js文本进行编辑，编辑内容如下

vi index.js

按“i”进行编辑

// dependencies

var async = require('async');

var AWS = require('aws-sdk');

var gm = require('gm')

.subClass({ imageMagick: true }); // Enable ImageMagick integration.

var util = require('util');

// constants

var MAX_WIDTH  = 100;

var MAX_HEIGHT = 100;

// get reference to S3 client

var s3 = new AWS.S3();

exports.handler = function(event, context, callback) {

// Read options from the event.

console.log("Reading options from event:\n", util.inspect(event, {depth: 5}));

var srcBucket = event.Records[0].s3.bucket.name;

// Object key may have spaces or unicode non-ASCII characters.

var srcKey    =

decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " "));

var dstBucket = srcBucket + "resized";

var dstKey    = "resized-" + srcKey;

// Sanity check: validate that source and destination are different buckets.

if (srcBucket == dstBucket) {

callback("Source and destination buckets are the same.");

return;

}

// Infer the image type.

var typeMatch = srcKey.match(/\.([^.]*)$/);

if (!typeMatch) {

callback("Could not determine the image type.");

return;

}

var imageType = typeMatch[1];

if (imageType != "jpg" && imageType != "png") {

callback('Unsupported image type: ${imageType}');

return;

}

// Download the image from S3, transform, and upload to a different S3 bucket.

async.waterfall([

function download(next) {

// Download the image from S3 into a buffer.

s3.getObject({

Bucket: srcBucket,

Key: srcKey

},

next);

},

function transform(response, next) {

gm(response.Body).size(function(err, size) {

// Infer the scaling factor to avoid stretching the image unnaturally.

var scalingFactor = Math.min(

MAX_WIDTH / size.width,

MAX_HEIGHT / size.height

);

var width  = scalingFactor * size.width;

var height = scalingFactor * size.height;

// Transform the image buffer in memory.

this.resize(width, height)

.toBuffer(imageType, function(err, buffer) {

if (err) {

next(err);

} else {

next(null, response.ContentType, buffer);

}

});

});

},

function upload(contentType, data, next) {

// Stream the transformed image to a different S3 bucket.

s3.putObject({

Bucket: dstBucket,

Key: dstKey,

Body: data,

ContentType: contentType

},

next);

}

], function (err) {

if (err) {

console.error(

'Unable to resize ' + srcBucket + '/' + srcKey +

' and upload to ' + dstBucket + '/' + dstKey +

' due to an error: ' + err

);

} else {

console.log(

'Successfully resized ' + srcBucket + '/' + srcKey +

' and uploaded to ' + dstBucket + '/' + dstKey

);

}

callback(null, "message");

}

);

};

编辑完毕按“Esc”退出，然后按“：wq”→enter保存退出

⑥当前路径下应有如下内容

index.js

/node_modules/gm

/node_modules/async

对如下内容进行打包

命令：

tar -czvf  ./*  ./CreateThumbnail.zip

然后把包导出来

⑦创建IAM角色

⑧在lambda上上传压缩包

⑨在lambda上进行S3的调用测试

代码如下

{

"Records":[

{

"eventVersion":"2.0",

"eventSource":"aws:s3",

"awsRegion":"us-west-2",

"eventTime":"1970-01-01T00:00:00.000Z",

"eventName":"ObjectCreated:Put",

"userIdentity":{

"principalId":"AIDAJDPLRKLG7UEXAMPLE"

},

"requestParameters":{

"sourceIPAddress":"127.0.0.1"

},

"responseElements":{

"x-amz-request-id":"C3D13FE58DE4C810",

"x-amz-id-2":"FMyUVURIY8/IgAtTv8xRjskZQpcIZ9KG4V5Wp6S7S/JRWeUWerMUE5JgHvANOjpD"

},

"s3":{

"s3SchemaVersion":"1.0",

"configurationId":"testConfigRule",

"bucket":{

"name":"sourcebucket",

"ownerIdentity":{

"principalId":"A3NL1KOZZKExample"

},

"arn":"arn:aws:s3:::sourcebucket"

},

"object":{

"key":"HappyFace.jpg", #S3source 桶里面放的文件名

"size":1024,

"eTag":"d41d8cd98f00b204e9800998ecf8427e",

"versionId":"096fKKXTRTtl3on89fVO.nfljtsv6qko"

}

}

}

]

}

⑩在S3那个sourceresized的S3桶里查看是否有文件生成

生成为成功，没有内容再调查问题原因。