Wire optional graceful announce-before-stop into the entrypoint (#651)

Author: morrissimo

Dockerfile

@@ -18,7 +18,10 @@ VOLUME ["/data"]
 
 WORKDIR /data
 
-ENTRYPOINT ["/usr/local/bin/entrypoint-demoter", "--match", "/data", "--debug", "--stdin-on-term", "stop", "/opt/bedrock-entry.sh"]
+# demoter-entry.sh execs into entrypoint-demoter (PID 1). By default it builds the
+# same args as before (--match /data --debug --stdin-on-term stop /opt/bedrock-entry.sh);
+# set STOP_SERVER_ANNOUNCE_DELAY to opt into a graceful announce-then-wait before stop.
+ENTRYPOINT ["/opt/demoter-entry.sh"]
 
 ARG APPS_REV=1
 ARG GITHUB_BASEURL=https://github.com

README.md

@@ -74,6 +74,8 @@ For Minecraft Java Edition you'll need to use this image instead:
 - `MC_PACK` (no default): Path inside the container to a single archive file (e.g. `.mcpack`, `.mcworld`, `.mctemplate`, `.mcaddon`, or any zip) or to a directory with the same layout. At startup the archive is unpacked (or the directory is read): top-level `behavior_packs/` is merged into `behavior_packs/`, top-level `resource_packs/` into `resource_packs/`, and all other content (when `level.dat` is present) into `worlds/{LEVEL_NAME}`. For `.mcaddon` archives, which use root-level `data/` (behavior) and `resources/` (resource) folders instead of `behavior_packs/` and `resource_packs/`, these are detected and installed automatically using the pack UUID from each manifest as the folder name.
 - `FORCE_WORLD_COPY` (default `false`): When `MC_PACK` contains a world (`level.dat`), set to `true` to remove and replace the existing `worlds/{LEVEL_NAME}` on every startup; otherwise the world is copied only when it does not exist.
 - `FORCE_PACK_COPY` (default `false`): When `MC_PACK` contains `behavior_packs/` or `resource_packs/`, set to `true` to remove and replace existing pack folders with the same name on every startup; otherwise each pack is copied only when it does not already exist.
+- `STOP_SERVER_ANNOUNCE_DELAY` (no default — disabled): opt into a graceful shutdown announcement. When set to a positive whole number of seconds, a heads-up line is written to the server console on container stop (`SIGTERM`); after that many seconds the server is sent `stop` (the usual clean-save shutdown). Unset or `0` keeps the previous behavior of stopping immediately. A second `SIGTERM` skips the remaining wait. Keep the value shorter than the container's stop grace period (e.g. `docker stop -t`, ECS `stopTimeout`, or an EC2 Spot interruption's ~2‑minute window) so the world save isn't cut short by `SIGKILL`.
+- `STOP_SERVER_ANNOUNCE` (default `say Server shutting down in %delay% seconds`): the console line written as the announcement when `STOP_SERVER_ANNOUNCE_DELAY` is active. The `%delay%` token is replaced with the delay's whole-second value. Any server command works (e.g. a `say` or `tellraw`).
 
 
 ### Server Properties

demoter-entry.sh

@@ -0,0 +1,39 @@
+#!/bin/bash
+
+set -eo pipefail
+
+# Entrypoint wrapper that launches entrypoint-demoter (as PID 1) for the Bedrock
+# server, optionally enabling a graceful "announce, wait, then stop" on SIGTERM.
+#
+# Why a wrapper: entrypoint-demoter is PID 1 and handles SIGTERM by writing the
+# --stdin-on-term message ("stop") to the server's stdin (the save-clean path).
+# To also warn players first, its v0.5.0 --stdin-on-term-announce / -delay flags
+# must be present on the command line *before* the process starts, so we build the
+# argument list here from the environment and exec into it.
+#
+# Default behaviour is UNCHANGED: with no env set, SIGTERM still sends "stop"
+# immediately (same args as the previous static ENTRYPOINT).
+#
+# Opt-in graceful shutdown:
+#   STOP_SERVER_ANNOUNCE_DELAY  Whole seconds to wait between the announce and the
+#                               stop. Unset or 0 => disabled (immediate stop).
+#                               Keep it shorter than the container's stop grace
+#                               period (docker `stop -t` / ECS stopTimeout / a Spot
+#                               interruption's 2-minute window) so the world save
+#                               isn't cut short by SIGKILL.
+#   STOP_SERVER_ANNOUNCE        Console line written as the heads-up. The %delay%
+#                               token is replaced by entrypoint-demoter with the
+#                               whole-second value of the delay.
+#                               Default: "say Server shutting down in %delay% seconds"
+
+demoterArgs=(--match /data --debug)
+
+delay="${STOP_SERVER_ANNOUNCE_DELAY:-0}"
+if [[ "${delay}" =~ ^[0-9]+$ ]] && (( delay > 0 )); then
+  announce="${STOP_SERVER_ANNOUNCE:-say Server shutting down in %delay% seconds}"
+  demoterArgs+=(--stdin-on-term-announce "${announce}" --stdin-on-term-delay "${delay}s")
+fi
+
+demoterArgs+=(--stdin-on-term stop)
+
+exec /usr/local/bin/entrypoint-demoter "${demoterArgs[@]}" /opt/bedrock-entry.sh