ConceptsDeploys

The port of your app

Ferry chooses one container port at each deploy and gives it to your app in PORT.

Port setting. The port setting of the service (--port).

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Ferry uses the first value that it finds

What your app must do

Listen on the port in PORT, on the address 0.0.0.0.

server.js

const port = process.env.PORT;
app.listen(port, '0.0.0.0');

An app that listens on 127.0.0.1 in its container gets no traffic.

The deploy log shows the port and where it comes from.

Deploy log

==> Using port 8000 (EXPOSEd by the image)

Health checks

A health check is the test that a new instance must pass before it gets traffic.

Settings and the live deploy

A live deploy keeps a snapshot of its settings. A change applies at the next deploy or restart.