Add guide for deployment to Koyeb.

Fix #1369.

docs/howto/fly.rst

@@ -1,5 +1,5 @@
 Deploy to Fly
-================
+=============
 
 This guide describes how to deploy a websockets server to Fly_.
 

docs/howto/heroku.rst

@@ -58,12 +58,10 @@ on websockets:
 .. literalinclude:: ../../example/deployment/heroku/requirements.txt
     :language: text
 
-Create a ``Procfile``.
+Create a ``Procfile`` to tell Heroku how to run the app.
 
 .. literalinclude:: ../../example/deployment/heroku/Procfile
 
-This tells Heroku how to run the app.
-
 Confirm that you created the correct files and commit them to git:
 
 .. code-block:: console

docs/howto/index.rst

@@ -48,6 +48,7 @@ Once your application is ready, learn how to deploy it on various platforms.
    :titlesonly:
 
    render
+   koyeb
    fly
    heroku
    kubernetes

docs/howto/koyeb.rst

@@ -0,0 +1,165 @@
+Deploy to Koyeb
+================
+
+This guide describes how to deploy a websockets server to Koyeb_.
+
+.. _Koyeb: https://www.koyeb.com
+
+.. admonition:: The free tier of Koyeb is sufficient for trying this guide.
+    :class: tip
+
+    The `free tier`__ include one web service, which this guide uses.
+
+    __ https://www.koyeb.com/pricing
+
+We’re going to deploy a very simple app. The process would be identical to a
+more realistic app.
+
+Create repository
+-----------------
+
+Koyeb supports multiple deployment methods. Its quick start guides recommend
+git-driven deployment as the first option. Let's initialize a git repository:
+
+.. code-block:: console
+
+    $ mkdir websockets-echo
+    $ cd websockets-echo
+    $ git init -b main
+    Initialized empty Git repository in websockets-echo/.git/
+    $ git commit --allow-empty -m "Initial commit."
+    [main (root-commit) 740f699] Initial commit.
+
+Render requires the git repository to be hosted at GitHub.
+
+Sign up or log in to GitHub. Create a new repository named ``websockets-echo``.
+Don't enable any of the initialization options offered by GitHub. Then, follow
+instructions for pushing an existing repository from the command line.
+
+After pushing, refresh your repository's homepage on GitHub. You should see an
+empty repository with an empty initial commit.
+
+Create application
+------------------
+
+Here’s the implementation of the app, an echo server. Save it in a file
+called ``app.py``:
+
+.. literalinclude:: ../../example/deployment/koyeb/app.py
+    :language: python
+
+This app implements typical requirements for running on a Platform as a Service:
+
+* it listens on the port provided in the ``$PORT`` environment variable;
+* it provides a health check at ``/healthz``;
+* it closes connections and exits cleanly when it receives a ``SIGTERM`` signal;
+  while not documented, this is how Koyeb terminates apps.
+
+Create a ``requirements.txt`` file containing this line to declare a dependency
+on websockets:
+
+.. literalinclude:: ../../example/deployment/koyeb/requirements.txt
+    :language: text
+
+Create a ``Procfile`` to tell Koyeb how to run the app.
+
+.. literalinclude:: ../../example/deployment/koyeb/Procfile
+
+Confirm that you created the correct files and commit them to git:
+
+.. code-block:: console
+
+    $ ls
+    Procfile         app.py           requirements.txt
+    $ git add .
+    $ git commit -m "Initial implementation."
+    [main f634b8b] Initial implementation.
+     3 files changed, 39 insertions(+)
+     create mode 100644 Procfile
+     create mode 100644 app.py
+     create mode 100644 requirements.txt
+
+The app is ready. Let's deploy it!
+
+Deploy application
+------------------
+
+Sign up or log in to Koyeb.
+
+In the Koyeb control panel, create a web service with GitHub as the deployment
+method. Install and authorize Koyeb's GitHub app if you haven't done that yet.
+
+Follow the steps to create a new service:
+
+1. Select the ``websockets-echo`` repository in the list of your repositories.
+2. Confirm that the **Free** instance type is selected. Click **Next**.
+3. Configure health checks: change the protocol from TCP to HTTP and set the
+   path to ``/healthz``. Review other settings; defaults should be correct.
+   Click **Deploy**.
+
+Koyeb builds the app, deploys it, verifies that the health checks passes, and
+makes the deployment active.
+
+Validate deployment
+-------------------
+
+Let's confirm that your application is running as expected.
+
+Since it's a WebSocket server, you need a WebSocket client, such as the
+interactive client that comes with websockets.
+
+If you're currently building a websockets server, perhaps you're already in a
+virtualenv where websockets is installed. If not, you can install it in a new
+virtualenv as follows:
+
+.. code-block:: console
+
+    $ python -m venv websockets-client
+    $ . websockets-client/bin/activate
+    $ pip install websockets
+
+Look for the URL of your app in the Koyeb control panel. It looks like
+``https://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/``. Connect the
+interactive client — you must replace ``https`` with ``wss``  in the URL:
+
+.. code-block:: console
+
+    $ python -m websockets wss://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/
+    Connected to wss://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/.
+    >
+
+Great! Your app is running!
+
+Once you're connected, you can send any message and the server will echo it,
+or press Ctrl-D to terminate the connection:
+
+.. code-block:: console
+
+    > Hello!
+    < Hello!
+    Connection closed: 1000 (OK).
+
+
+You can also confirm that your application shuts down gracefully.
+
+Connect an interactive client again:
+
+.. code-block:: console
+
+    $ python -m websockets wss://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/
+    Connected to wss://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/.
+    >
+
+In the Koyeb control panel, go to the **Settings** tab, click **Pause**, and
+confirm.
+
+Eventually, the connection gets closed with code 1001 (going away).
+
+.. code-block:: console
+
+    $ python -m websockets wss://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/
+    Connected to wss://<koyeb-app>-<github-user>-<koyeb-app-id>.koyeb.app/.
+    Connection closed: 1001 (going away).
+
+If graceful shutdown wasn't working, the server wouldn't perform a closing
+handshake and the connection would be closed with code 1006 (abnormal closure).

docs/spelling_wordlist.txt

@@ -38,6 +38,7 @@ iterable
 js
 keepalive
 KiB
+Koyeb
 kubernetes
 lifecycle
 linkerd

example/deployment/koyeb/Procfile

@@ -0,0 +1 @@
+web: python app.py

example/deployment/koyeb/app.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+
+import asyncio
+import http
+import os
+import signal
+
+from websockets.asyncio.server import serve
+
+
+async def echo(websocket):
+    async for message in websocket:
+        await websocket.send(message)
+
+
+def health_check(connection, request):
+    if request.path == "/healthz":
+        return connection.respond(http.HTTPStatus.OK, "OK\n")
+
+
+async def main():
+    # Set the stop condition when receiving SIGINT.
+    loop = asyncio.get_running_loop()
+    stop = loop.create_future()
+    loop.add_signal_handler(signal.SIGINT, stop.set_result, None)
+
+    async with serve(
+        echo,
+        host="",
+        port=int(os.environ["PORT"]),
+        process_request=health_check,
+    ):
+        await stop
+
+
+if __name__ == "__main__":
+    asyncio.run(main())

example/deployment/koyeb/requirements.txt

@@ -0,0 +1 @@
+websockets