Read file from S3 into a buffer

user_13757207 0
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I am trying to write a function in Lambda that requires a file from S3 to be read into a buffer. I have seen multiple examples of them being read into streams but none with buffers. My current code for getting the object is

exports.handler = async (event, context, callback) => {

    //console.log("Reading options from event:\n", util.inspect(event, {depth: 5}));
    const srcBucket = event.Records[0].s3.bucket.name;
    const srcKey    = decodeURIComponent(event.Records[0].s3.object.key.replace(/\+/g, " "));

    const params = 
        {
            Bucket: srcBucket,
            Key: srcKey
        };

    try 
    {
        var slippiGame = s3.getObject(params, function(error, data) 
        {
            if (error)
            {
                console.log(error);
            }
            else
            {
                const game = new SlippiGame(slippiGame);
            }
        });
    } 
    catch (e) 
    {
        console.log("fail");
        console.log(e);
    }

    console.log(slippiGame);

    return("success");
};

I know that this approach is wrong since my slippiGame variable isn't a buffer and the SlippiGame constructor only takes a local file or a buffer. Is there a way to either store the file from S3 temporarily in the Lambda directory or create a buffer to hold the S3 file in?

aws-lambda node.js amazon-web-services amazon-s3
1 Answers

The Body attribute of data is already a Buffer.

If you prefer file download, create a read stream from the response and pipe it to a write stream. See here for more.

const s3 = new AWS.S3({apiVersion: '2006-03-01'});
const params = {Bucket: 'myBucket', Key: 'myImageFile.jpg'};
const file = require('fs').createWriteStream('/path/to/file.jpg');
s3.getObject(params).createReadStream().pipe(file);

One additional problem with your current code: you are mixing the async and the callback variants of the Lambda function handler -- it's better to just use the async variant and get rid of callback

user_2714150
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