How do I stream data to browsers with Hapi?

Question

I'm trying to use streams to send data to the browser with Hapi, but can't figure our how. Specifically I am using the request module. According to the docs the reply object accepts a stream so I have tried:

reply(request.get('https://google.com'));

The throws an error. In the docs it says the stream object must be compatible with streams2, so then I tried:

reply(streams2(request.get('https://google.com')));

Now that does not throw a server side error, but in the browser the request never loads (using chrome).

I then tried this:

var stream = request.get('https://google.com');
stream.on('data', data => console.log(data));
reply(streams2(stream));

And in the console data was outputted, so I know the stream is not the issue, but rather Hapi. How can I get streaming in Hapi to work?

Answer 1

Try using Readable.wrap:

var Readable = require('stream').Readable;
...
function (request, reply) {

  var s = Request('http://www.google.com');
  reply(new Readable().wrap(s));
}

Tested using Node 0.10.x and hapi 8.x.x. In my code example Request is the node-request module and request is the incoming hapi request object.

UPDATE

Another possible solution would be to listen for the 'response' event from Request and then reply with the http.IncomingMessage which is a proper read stream.

function (request, reply) {

     Request('http://www.google.com')
     .on('response', function (response) {
        reply(response);
     });
}

This requires fewer steps and also allows the developer to attach user defined properties to the stream before transmission. This can be useful in setting status codes other than 200.

Answer 2

2020

I found it !! the problem was the gzip compression

to disable it just for event-stream you need provide the next config to Happi server

const server = Hapi.server({
  port: 3000, 
  ...
  mime:{
    override:{
      'text/event-stream':{
        compressible: false
      }
    }
  }
});

in the handler I use axios because it support the new stream 2 protocol

async function handler(req, h) {
    const response = await axios({
        url: `http://some/url`,
        headers: req.headers,
        responseType: 'stream'
    });

    return response.data.on('data',function (chunk) {
        console.log(chunk.toString());
    })

    /* Another option with h2o2, not fully checked */
    // return h.proxy({
    //     passThrough:true,
    //     localStatePassThrough:true,
    //     uri:`http://some/url`
    // });
};