Web gateway

zettcode gateway serves a web page for the background agents on this machine. It is a page, not an agent: a left rail with the chats, a list of daemons and sessions, and a conversation. It works on a phone as well, which is the point — the terminal stays where the code is, and the page follows you.

zettcode gateway                    # serve here until Ctrl-C
zettcode gateway --port 9000        # the same, somewhere else

The page is served on 127.0.0.1:8765 by default. Start it once, then open the address it prints.

Running it in the background

zettcode gateway start              # detach, return at once, keep it running
zettcode gateway stop               # stop the one that is running
zettcode gateway restart            # stop it and start again

start says where the page is and how to sign in, writes its output to gateway.log in the gateway's folder (~/.zettcode/gateway by default, or --directory), and returns once the page answers. restart with no flags keeps the settings the running gateway was started with — host, port, token, roots — so restarting does not quietly change the address or lose the sign-in. Give a flag to change one (zettcode gateway restart --port 9000 --token new).

Only a process recognised as the gateway is ever signalled: stopping checks the command line first, so a stale record or a reused process id cannot end something else. A gateway that is not running is not an error; stop says so and exits 0. The one exception is a process that exists but whose command line cannot be read: stop keeps its record and exits 1 rather than guess, because that process may be the gateway.

Signing in and who may use it

• With no --token there is no sign-in, and the gateway only listens on this machine. The page prints the URL with nothing to type beyond it.
• With --token (or $ZETTCODE_GATEWAY_TOKEN) the page asks for that token once and keeps a cookie.
• Listening beyond this machine (--host 0.0.0.0) requires a token: without one anybody who can reach the port could run commands as you. The page is plain HTTP; put it behind TLS if it leaves the machine.
• -r/--root limits where a daemon may be started; by default any directory may be chosen. --no-full refuses to start daemons at the full shell level (no sandbox and no approval); --full allows it again after a recorded --no-full.

What the page can do

The page lists the daemons and the other sessions this machine has. A daemon can be started and stopped from it, and any of them can be talked to as a contact: what you type is sent as a message from the gateway, and what the session says comes back into the same conversation. A message from the page waits for the session's current request to end: the page does not show that request live, so it never changes one you cannot watch. (The terminal asks whether to steer; the page simply waits.) The gateway is a session of its own, registered with the broker like a terminal's, so the daemons see a person's messages — not an agent's. Its name is Web gateway.

The gateway needs a model configured, because its session is a real one, though it never calls the model itself. No model is the one reason start can fail with a message instead of a page; the log says so.