How to Pass Credentials to Websocket from external domain?

Hi @keithg,

New in Mattermost 3.5, you can authenticate your WebSocket by connecting and then providing the token in a JSON formatted authentication challenge over the WebSocket.

An example authentication challenge would look like this:

{
    "seq": 1,
    "action": "authentication_challenge",
    "data": {
        "token": "mattermosttokengoeshere"
    }
}

If the WebSocket authenticates correctly then you will receive a standard ok response looking like this:

{
    "status": "OK",
    "seq_reply": 1
}

All previous versions of Mattermost before 3.5 will require the token in the cookie. Mattermost 3.5 still supports authenticating through the cookie.