Amazon Rekognition 연동하기

// photo-albums/amplify/backend/function/workshopphotoprocessor/src/index.js

const AWS = require('aws-sdk');
const S3 = new AWS.S3({ signatureVersion: 'v4' });
const Rekognition = new AWS.Rekognition();
const DynamoDBDocClient = new AWS.DynamoDB.DocumentClient({apiVersion: '2012-08-10'});
const uuidv4 = require('uuid/v4');

/*
Note: Sharp requires native extensions to be installed in a way that is compatible
with Amazon Linux (in order to run successfully in a Lambda execution environment).

If you're not working in Cloud9, you can follow the instructions on http://sharp.pixelplumbing.com/en/stable/install/#aws-lambda how to install the module and native dependencies.
*/
const Sharp = require('sharp');

// We'll expect these environment variables to be defined when the Lambda function is deployed
const THUMBNAIL_WIDTH = parseInt(process.env.THUMBNAIL_WIDTH, 10);
const THUMBNAIL_HEIGHT = parseInt(process.env.THUMBNAIL_HEIGHT, 10);
const DYNAMODB_PHOTOS_TABLE_NAME = process.env.DYNAMODB_PHOTOS_TABLE_ARN.split('/')[1];

async function getLabelNames(bucketName, key) {
  let params = {
    Image: {
      S3Object: {
        Bucket: bucketName, 
        Name: key
      }
    }, 
    MaxLabels: 50, 
    MinConfidence: 70
  };
  const detectionResult = await Rekognition.detectLabels(params).promise();
  const labelNames = detectionResult.Labels.map((l) => l.Name.toLowerCase()); 
  return labelNames;
}

function storePhotoInfo(item) {
    const params = {
        Item: item,
        TableName: DYNAMODB_PHOTOS_TABLE_NAME
    };
    return DynamoDBDocClient.put(params).promise();
}

async function getMetadata(bucketName, key) {
    const headResult = await S3.headObject({Bucket: bucketName, Key: key }).promise();
    return headResult.Metadata;
}

function thumbnailKey(filename) {
    return `public/resized/${filename}`;
}

function fullsizeKey(filename) {
    return `public/${filename}`;
}

function makeThumbnail(photo) {
    return Sharp(photo).resize(THUMBNAIL_WIDTH, THUMBNAIL_HEIGHT).toBuffer();
}

async function resize(bucketName, key) {
    const originalPhoto = (await S3.getObject({ Bucket: bucketName, Key: key }).promise()).Body;
    const originalPhotoName = key.replace('uploads/', '');
    const originalPhotoDimensions = await Sharp(originalPhoto).metadata();

    const thumbnail = await makeThumbnail(originalPhoto);

    await Promise.all([
        S3.putObject({
            Body: thumbnail,
            Bucket: bucketName,
            Key: thumbnailKey(originalPhotoName),
        }).promise(),

        S3.copyObject({
            Bucket: bucketName,
            CopySource: bucketName + '/' + key,
            Key: fullsizeKey(originalPhotoName),
        }).promise(),
    ]);

    await S3.deleteObject({
        Bucket: bucketName,
        Key: key
    }).promise();

    return {
        photoId: originalPhotoName,
        
        thumbnail: {
            key: thumbnailKey(originalPhotoName),
            width: THUMBNAIL_WIDTH,
            height: THUMBNAIL_HEIGHT
        },

        fullsize: {
            key: fullsizeKey(originalPhotoName),
            width: originalPhotoDimensions.width,
            height: originalPhotoDimensions.height
        }
    };
};

async function processRecord(record) {
    const bucketName = record.s3.bucket.name;
    const key = record.s3.object.key;
    
    if (key.indexOf('uploads') != 0) return;
    
    const metadata = await getMetadata(bucketName, key);
    const sizes = await resize(bucketName, key);   
    const labelNames = await getLabelNames(bucketName, sizes.fullsize.key);
    const id = uuidv4();
    const item = {
        id: id,
        owner: metadata.owner,
        labels: labelNames,
        photoAlbumId: metadata.albumid,
        bucket: bucketName,
        thumbnail: sizes.thumbnail,
        fullsize: sizes.fullsize,
        createdAt: new Date().getTime()
    }
    await storePhotoInfo(item);
}

exports.handler = async (event, context, callback) => {
    try {
        event.Records.forEach(processRecord);
        callback(null, { status: 'Photo Processed' });
    }
    catch (err) {
        console.error(err);
        callback(err);
    }
};