Webpack Dev Server running on HTTPS/Web Sockets Secure

this for TEST environment only:

you need to configure your webpack-dev-server as follows:

webpack-dev-server --https --cert ./cert.pem --key ./key.pem

The easiest work around is to generate a key with no passphrase (I don't know the security consequences of this! but this is for test only) .

To take the passphrase out of your key use this command:

$ openssl rsa -in key.pem -out newKey.pem

and use the new key in the previews configuration line

While the above answer is correct for cli, if you are not in the CLI, you could do something like this (in a gulp task):

var WebpackDevServer = require('webpack-dev-server');

new WebpackDevServer(webpack(WebpackDevConfig), {
    https: true,
    hot: true,
    watch: true,
    contentBase: path.join(__dirname, 'src'),
    historyApiFallback: true
}).listen(1337, 'localhost', function(err, result) {
    if (err) {
        console.log(err);
    }
    console.log('Dev server running at https://localhost:1337');
});

See the webpack docs

There is a flag you can add to the webpack-dev-server command

webpack-dev-server --https