Cognitive Service Container Proxy Example

CognitiveServiceContainerProxyExample.js

// Cognitive Service containers don't currently handle Cross-origin resource sharing (CORS) headers.  This means that for user agents
// that enforce CORS (browsers, typically), requests will fail.  The following code is an example of how you might work around this,
// temporarily, until the containers are fixed.  This code is provided as-is, with no guarantees.
//
// The following is a modified version of code found here: https://github.com/ccoenraets/cors-proxy.

var express = require('express'),
    request = require('request'),
    bodyParser = require('body-parser'),
    app = express();

let ocrBase = 'http://localhost:5000'; // Adjust if necessary

app.use(bodyParser.raw({
    limit: '4MB',
    type: '*/*'
}));

app.all('*', function (req, res, next) {

    // Set CORS headers: allow all origins, methods, and headers: you may want to lock this down in a production environment
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Methods", "GET, PUT, PATCH, POST, DELETE");
    res.header("Access-Control-Allow-Headers", req.header('access-control-request-headers'));

    if (req.method === 'OPTIONS') {
        // CORS Preflight
        res.send();
    } else {
        new_req = {
            url: ocrBase + req.url,
            method: req.method,
            query: req.query,
            headers: req.headers,
            body: req.body
        };
        request(new_req,
            function (error, response, body) {
                if (error) {
                    console.error('error: ' + response)
                }
            }).pipe(res);
    }
});

app.set('port', process.env.PORT || 3000);

app.listen(app.get('port'), function () {
    console.log('Proxy server listening on port ' + app.get('port'));
});