Skip to main content

Deployment

Beta software

connect-python is in beta. 1.0 will include a new Protobuf implementation built from scratch by Buf, which may introduce breaking changes. Join us on Slack if you have questions or feedback.

After building a Connect service, you still need to deploy it to production. This guide covers how to use a Python application server to run a service.

Application Servers​

Connect services are standard ASGI or WSGI applications that can be run with an off-the-shelf Python application server. Generally, any experience in running a Python application can be applied to running Connect as-is.

HTTP/1.1​

Connect only requires HTTP/2 for bidirectional streaming RPCs - the vast majority of services can be run using HTTP/1.1 without issue. Two servers have long been in use with HTTP/1.1 and have a proven track record. If you are unsure what server to use, it is generally a safe bet to use one of them:

HTTP/2​

If your service uses bidirectional or otherwise want to use HTTP/2, the above servers will not work. HTTP/2 support in the Python ecosystem is still relatively young - servers known to support HTTP/2 with bidirectional streaming are:

Connect has an extensive test suite to verify compatibility of connect-python with the Connect protocol. Unfortunately, only pyvoy reliably passes conformance tests: other servers occasionally have hung requests or stream ordering issues. pyvoy was built with connect-python in mind, but is very new and needs more time with real-world applications to verify stability.

Keep the above in mind when picking an HTTP/2 server and let us know how it goes if you give any a try. When in doubt, if you do not use bidirectional streaming, we recommend one of the HTTP/1.1 servers.

CORS​

Cross-origin resource sharing (CORS) is needed to support web clients on other origins other than the server's own. Connect services are standard ASGI and WSGI applications, so any CORS middleware can be used to enable CORS.

For example, with an ASGI application using the asgi-cors middleware:

from asgi_cors import asgi_cors

from greet.v1.greet_connect import GreetServiceASGIApplication
from server import Greeter

app = GreetServiceASGIApplication(Greeter())

# app is a standard ASGI application - any middleware works as-is
app = asgi_cors(
    app,
    hosts=["https://acme.com"],
    # POST is used for all APIs except for idempotent unary RPCs that may support GET
    methods=["GET", "POST"],
    headers=[
        "content-type",
        "connect-protocol-version",
        "connect-timeout-ms",
        "x-user-agent",
    ],
)