Home Assistant

Server-sent events

The server-sent events feature is a one-way channel from your Home Assistant server to a client which is acting as a consumer. For bi-directional communication check the RESTful API and Python API.

The URI that is generating the data is /api/stream.

A requirement on the client-side is existing support for the EventSource interface.

There are various ways to access the stream. If you have not set an api_password in the http section of your configuration.yaml file then you use your modern browser to read the messages. A command-line option is curl:

$ curl -X GET -H "x-ha-access: YOUR_PASSWORD" \
       -H "Content-Type: application/json" http://localhost:8123/api/stream

You can create a convenient view for this by creating an HTML file (sse.html) in the www folder of your Home Assistant configuration directory (.homeassistant). Paste this snippet into the file:

<!DOCTYPE html>
<html>
<body>
    <h1>Getting Home Assistant server events</h1>
    <div id="events"></div>
    <script type="text/javascript">
        var source = new EventSource("/api/stream?api_password=YOUR_PASSWORD");
        source.onmessage = function(event) {
            document.getElementById("events").innerHTML += event.data + "<br>";
        };
    </script>
</body>
</html>

Visit http://localhost:8123/local/sse.html to see the stream of events.

Examples

A simple way to consume server-sent events is to use a command-line http client like httpie. Installation info is on the site (if you use Homebrew, it’s brew install httpie). Once installed, run this snippet from your terminal:

$ http --stream http://localhost:8123/api/stream x-ha-access:YOUR_PASSWORD content-type:application/json

Website

The home-assistant-sse repository contains a more advanced example.

Python

If you want to test the server-sent events without creating a website, the Python module sseclient can help. To install (assuming Python and pip3 are already installed):

$ pip3 install sseclient

A simple script to consume SSE in Python looks like this:

from sseclient import SSEClient

messages = SSEClient('http://localhost:8123/api/stream?api_password=YOUR_PASSWORD')
for msg in messages:
    print(msg)