build(docker): stop containers with the default SIGTERM

The compose services overrode the stop signal with SIGINT, because the
applications waited only on that one. They now handle SIGTERM as well, so
the override is redundant: dropping it also means an image stopped outside
this compose file, by plain `docker stop`, systemd or kubernetes, shuts
down gracefully instead of being killed outright.

The ENTRYPOINT comment no longer names a specific signal, since the point
it makes about `exec` and PID 1 holds for either one.

Author: plebhash

docker/Dockerfile

@@ -71,5 +71,5 @@ COPY --from=builder /app/release/${APP} /app/${APP}
 # the binary would otherwise read from its working directory is simply absent.
 #
 # `exec` replaces the shell so the app runs as PID 1 and receives the container's
-# stop signal (SIGINT) directly, allowing graceful shutdown.
+# stop signal directly, allowing graceful shutdown.
 ENTRYPOINT ["/bin/sh", "-c", "exec /app/${APP}"]

docker/docker-compose.yml

@@ -2,7 +2,6 @@ services:
   pool_sv2:
     image: stratumv2/pool_sv2:main
     container_name: pool_sv2
-    stop_signal: SIGINT
     # The pool is configured entirely from POOL__* variables in docker_env;
     # there is no config file to mount.
     env_file:
@@ -22,7 +21,6 @@ services:
   jd_client_sv2:
     image: stratumv2/jd_client_sv2:main
     container_name: jd_client_sv2
-    stop_signal: SIGINT
     # Configured entirely from JDC__* variables in docker_env.
     env_file:
       - docker_env
@@ -39,7 +37,6 @@ services:
   tproxy_sv2:
     image: stratumv2/translator_sv2:main
     container_name: tproxy_sv2
-    stop_signal: SIGINT
     # Configured entirely from TPROXY__* variables in docker_env.
     env_file:
       - docker_env