syndicate-server supervised external service example -- see also https://git.syndicate-lang.org/syndicate-lang/syndicate-rs/src/commit/ec8ba36d6a7b0396c2b1bd083a4de20888e9b1ad/syndicate-server/protocols/schemas/externalServices.prs

inf.py

from syndicate import relay, turn
from syndicate.during import During
import logging

@relay.service(name='inf', debug=True)
@During().add_handler
def main(args):
    logging.info(f'in main {args}')
    turn.on_stop(lambda: logging.info(f'args retracted {args}'))

sub-py.pr

; Demand that the server solve dependencies and then start the service:
<require-service <daemon sub-py>>

; Specify what it means to start the sub-py daemon:
<daemon sub-py {
  ; This is the command line
  argv: ". ./.envrc >&2; /usr/bin/env python3 ./inf.py",
  ; This is the CWD for the subprocess
  dir: "/home/tonyg/src/syndicate-py",
  ; This specifies that the program expects to speak BINARY syndicate protocol on stdio
  protocol: application/syndicate,
}>

; As soon as the service starts, it publishes an object on well-known OID 0.
; The server advertises this fact as a `service-object` record.
; See https://git.syndicate-lang.org/syndicate-lang/syndicate-rs/src/commit/ec8ba36d6a7b0396c2b1bd083a4de20888e9b1ad/syndicate-server/src/services/daemon.rs#L345-L352
; When the service-object appears, take the published object ref ($cap) and
; assert its config object to it - here, a dictionary with two entries, but can be anything
? <service-object <daemon sub-py> ?cap> [
  $cap {
    config: $config,
    log: $log,
  }
]