fix: handle SIGTERM for graceful container shutdown (#1101)

## Summary
- Add a `trap` handler for SIGTERM/SIGINT that forwards signals to all
child processes
- Replace foreground `sleep infinity` with backgrounded `sleep infinity
& wait $!` so the trap can fire

**Root cause**: bash as PID 1 has no default SIGTERM handler, and
foreground `sleep infinity` blocks signal delivery. Docker sends SIGTERM
on stop, nothing handles it, so the container hangs until Docker sends
SIGKILL after the timeout.

Closes #1083

## Test plan
- [ ] `docker run --rm -d --name lgtm grafana/otel-lgtm` then `docker
stop lgtm` — should exit within a few seconds instead of hanging
- [ ] Verify all services start normally (health checks pass)

---------

Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>

Author: zeitlinger

docker/logging.sh

@@ -7,12 +7,11 @@ function run_with_logging() {
 	shift
 	envvar=$1
 	shift
-	command=$*
 	if [[ ${envvar} == "true" || ${ENABLE_LOGS_ALL:-false} == "true" ]]; then
 		echo "Running ${name} logging=true"
-		${command}
+		exec "$@"
 	else
 		echo "Running ${name} logging=false"
-		${command} >/dev/null 2>&1
+		exec "$@" >/dev/null 2>&1
 	fi
 }

docker/run-all.sh

@@ -2,6 +2,17 @@
 
 echo "Starting grafana/otel-lgtm ${LGTM_VERSION}"
 
+# Graceful shutdown: forward SIGTERM/SIGINT to all background jobs
+shutdown() {
+	echo "Shutting down..."
+	# Send SIGTERM to all background jobs (the wrapper scripts exec the
+	# server process, so these PIDs are the actual server processes)
+	jobs -p | xargs -r kill 2>/dev/null
+	wait
+	exit 0
+}
+trap shutdown SIGTERM SIGINT
+
 # Record global start time
 start_time_global=$(date +%s)
 
@@ -156,4 +167,6 @@ echo " - 3000: Grafana (http://localhost:3000). User: admin, password: admin"
 echo " - 4040: Pyroscope endpoint"
 echo " - 9090: Prometheus endpoint"
 
-sleep infinity
+# Wait for signal; backgrounded sleep allows the trap to fire
+sleep infinity &
+wait $!