When piping a movie from S3 the file isn't seekable - node.js

Question

We have an application that sometimes serves a MP4 file which is stored on S3, since only specific people should be able to see each file, the file is private and inside our service we will only show it to authorised people.
The movie starts playing correctly (in the browser's built in video tag), however if we seek to a point in the movie that hasn't been buffered yet, the player will buffer for a bit, then stop playing. Afterwards clicking Play will cause the movie to start from the beginning. If I make the file public and access it directly form S3 seeking to an unbuffered point works correctly.
I created a standalone node program that reproduces this problem. I tried to make the response headers identical to those that S3 sends but the problem remains.
const http = require("http");
const AWS = require("aws-sdk");
const proxy = require("proxy-agent");
Object.assign(process.env, {
AWS_ACCESS_KEY_ID: "REDACTED",
AWS_SECRET_ACCESS_KEY: "REDACTED",
AWS_EC2_REGION: "us-west-2"
});
const s3 = new AWS.S3({
s3ForcePathStyle: 'true',
signatureVersion: 'v4',
httpOptions: { timeout: 300000 },
endpoint: 'https://s3.us-west-2.amazonaws.com',
region: 'us-west-2'
});
const objectParams = {
Bucket: 'REDACTED',
Key: 'some-movie.mp4'
};
let request = 0;
function serve(req, res) {
console.log("Handling request", ++request, req.url);
s3.headObject(objectParams, (err, data) => {
if (err)
throw err;
const { ContentType: type, ContentLength: length} = data;
console.log("Got", data);
if (data.ETag)
res.setHeader("ETag", data.ETag);
const range = req.headers.range;
if (range) {
console.log("Serving range", range);
const parts = range.replace("bytes=", "").split("-");
const start = parseInt(parts[0], 10);
const end = parts[1]? parseInt(parts[1], 10): length -1;
let headers = {
"Content-Range": `bytes ${start}-${end}/${length}`,
"Accept-Ranges": "bytes",
"Content-Type": type,
"Content-Length": end - start + 1,
"Last-Modified": data.LastModified,
};
if (req.headers["if-range"]) {
console.log("Setting if-range to", req.headers["if-range"]);
headers["If-Range"] = req.headers["if-range"];
}
res.writeHead(206, headers);
}
else {
console.log("Whole file");
res.setHeader("Accept-Ranges", "bytes");
res.setHeader("Content-Type", type);
res.setHeader("Content-Length", length);
res.setHeader("Last-Modified", data.LastModified);
}
const stream = s3.getObject(objectParams).createReadStream();
stream.on("error", err => console.error("stream error:", err));
stream.pipe(res).on("finish", data => {
console.log("Finished streaming");
});
});
}
http.createServer(serve).listen(1234);
What am I missing?

Answer 1

Here is the code with seekbar working just fine. You can test by integrating the below code and just open the api url in the browser.
import mime from 'mime-types';
const key = 'S3_BUCKET KEY';
const params = { Key: key, Bucket: AWS_BUCKET };
//s3 here refers to AWS.S3 object.
s3.headObject(params, function (err, data) {
if (err) {
console.error(err);
return next(err);
}
if (req.headers.range) {
const range = req.headers.range;
const bytes = range.replace(/bytes=/, '').split('-');
const start = parseInt(bytes[0], 10);
const total = data.ContentLength;
const end = bytes[1] ? parseInt(bytes[1], 10) : total - 1;
const chunkSize = end - start + 1;
res.set('Content-Range', 'bytes ' + start + '-' + end + '/' + total);
res.set('Accept-Ranges', 'bytes');
res.set('Content-Length', chunkSize.toString());
params['Range'] = range;
console.log('video buffering - range, total, start, end ,params', range, total, start, end, params);
} else {
res.set('Content-Length', data.ContentLength.toString());
console.log('video buffering - ,params', params);
}
res.status(206);
res.set('Content-Type', mime.lookup(key));
res.set('Last-Modified', data.LastModified.toString());
res.set('ETag', data.ETag);
const stream = s3.getObject(params).createReadStream();
stream.on('error', function error(err) {
return next(err);
});
stream.on('end', () => {
console.log('Served by Amazon S3: ' + key);
});
stream.pipe(res);
});