OTP application entry point.

Boots arizona_sup, then -- if the server application env is set -- starts a listener named arizona_http through the arizona_server adapter its required adapter key names, a module of an adapter package the application depends on (arizona_roadrunner's arizona_roadrunner_server, arizona_cowboy's arizona_cowboy_server, ...). On shutdown, drains that listener in prep_stop/1 -- before the supervision tree goes down -- so it never serves a request against already-dead infrastructure (pubsub, the MCP registry, the session store); stop/1 re-runs the same idempotent cleanup as a backstop. Draining, not just stopping, is what lets clients come back: each live view gets handle_drain/2 and closes 1001, which web and native clients reconnect from, where a plain stop closes 1000, which they take as a deliberate end of session.

Server config

{arizona, [
    {server, #{
        adapter => arizona_roadrunner_server,           %% arizona_server module (required)
        scheme => http,                                 %% http | https
        transport_opts => [{port, 4040}],               %% port shorthand
        drain_timeout => 5000,                          %% ms a stop waits for sessions
        proto_opts => #{                                %% adapter-specific: roadrunner's
            max_clients => 200,
            max_content_length => 10485760
        },
        routes => [
            {live, ~"/", my_page, #{layouts => [{my_layout, render}]}},
            {ws, ~"/ws", #{}},
            {asset, ~"/priv", {priv_dir, my_app, "static"}}
        ]
    }}
]}

The server key is optional: if absent, only the supervisor starts (useful for tests that launch listeners manually).