prain stack: requires_NAME refuses to start without its services, merged --help

scripts/prain

@@ -1,6 +1,6 @@
 #!/bin/bash
 # prain front door. up, down, restart, status and logs drive the stack's OpenRC user
-# services (prain.NAME); run, need and wait are what those services call. Anything else
+# services (prain.NAME); run, deps and wait are what those services call. Anything else
 # goes to prain's own CLI in PRAIN_ROOT/.venv, with its scripts/env.sh sourced.
 set -euo pipefail
 
@@ -50,9 +50,18 @@ run)
 	prain_env
 	eval "exec ${cmd//$'\n'/ }"
 	;;
-need)
-	get need "$2"
-	echo
+deps)  # fail, without starting anything, unless the services NAME requires are up
+	for d in $(get requires "$2"); do
+		url=$(get ready "$d")
+		if [ -n "$url" ]; then
+			curl -sf -o /dev/null "$url" && continue
+		else
+			rc-service --user "prain.$d" status > /dev/null 2>&1 && continue
+		fi
+		echo "prain: $2 needs $d, which is not running${url:+ (no answer from $url)}." \
+			"Start it first: prain up $d" >&2
+		exit 1
+	done
 	;;
 wait)
 	url=$(get ready "$2")
@@ -64,10 +73,19 @@ wait)
 		sleep 2
 	done
 	;;
-'' | -h | --help)
-	echo "stack: prain up|down|restart|status|logs [NAME...]  (services: ${services[*]})"
+'' | -h | --help)  # prain's own help, with the stack commands merged into its list
 	prain_env
-	exec "$PRAIN_ROOT/.venv/bin/prain" --help
+	"$PRAIN_ROOT/.venv/bin/prain" --help | awk -v stack="$(cat <<-EOF
+		    up [NAME...]        start services (all: ${services[*]}), each waits until ready
+		    down [NAME...]      stop services, in reverse order
+		    restart [NAME...]   restart services
+		    status [NAME...]    show whether services run
+		    logs [NAME...]      follow service logs ($logdir/NAME.log)
+	EOF
+	)" '
+		/^(usage: prain|  )[^{]*\{/ { sub(/\{/, "{up,down,restart,status,logs,") }
+		{ print }
+		/^  \{/ { print stack }'
 	;;
 *)
 	prain_env