Depending on your setup and preferences, there are multiple ways to run Emmett applications. In this chapter, we'll try to document the most common ones.
If you want to use an ASGI server not listed in this section, please refer to its documentation, remembering that your Emmett application object is the actual ASGI application (following spec version 3.0).
Changed in version 2.2
Emmett comes with an included server based on uvicorn. In order to run your application in production you can just use the included serve command:
emmett serve --host 0.0.0.0 --port 80
You can inspect all the available options of the serve command using the --help option. Here is the full list:
| option | default | description |
|---|---|---|
| host | 0.0.0.0 | Bind address |
| port | 8000 | Bind port |
| workers | 1 | Number of worker processes |
| loop | auto | Loop implementation (possible values: auto,asyncio,uvloop) |
| http-protocol | auto | HTTP protocol implementation (possible values: auto,h11,httptools) |
| ws-protocol | auto | Websocket protocol implementation (possible values: auto,websockets,wsproto) |
| log-level | info | Logging level (possible values: debug,info,warning,error,critical) |
| access-log | (flag) enabled | Enable/disable access log |
| proxy-headers | (flag) disabled | Enable/disable proxy headers |
| proxy-trust-ips | Comma separated list of IPs to trust for proxy headers | |
| max-concurrency | Limit number of concurrent connections | |
| backlog | 2048 | Maximum connection queue |
| keep-alive-timeout | 0 | Connection keep-alive timeout |
| ssl-certfile | Path to SSL certificate file | |
| ssl-keyfile | Path to SSL key file | |
| ssl-cert-reqs | SSL client certificate requirements (see ssl module) |
|
| ssl-ca-certs | SSL CA allowed certificates |
The included server might suit most of the common demands, but whenever you need a fully featured server, you can use Gunicorn.
Emmett includes a Gunicorn worker class allowing you to run ASGI applications with the Emmett's environment, while also giving you Gunicorn's fully-featured process management:
gunicorn myapp:app -w 4 -k emmett.asgi.workers.EmmettWorker
This allows you to increase or decrease the number of worker processes on the fly, restart worker processes gracefully, or perform server upgrades without downtime.
Even if Docker is not properly a deployment option, we think giving an example of a Dockerfile for an Emmett application is proficient for deployment solutions using container orchestrators, such as Kubernetes or Mesos.
In order to keep the image lighter, we suggest to use the slim Python image as a source:
FROM python:3.9-slim
RUN mkdir -p /usr/src/deps
COPY requirements.txt /usr/src/deps
WORKDIR /usr/src/deps
RUN pip install --no-cache-dir -r /usr/src/deps/requirements.txt
COPY ./ /app
WORKDIR /app
EXPOSE 8000
CMD [ "emmett", "serve" ]